Migrate from Gradle to Maven.

- Restructure source to src/{main,test} style
- Add pom.xml and update Android.mk
- Migrate all tests to JUnit4 and Robolectric
 - RequestQueueTest is currently @Ignored as fixing it will
   involve more extensive refactoring.
- Main library still builds in Gradle; tests do not

Change-Id: I1edc53bb1a54f64d3e806e4572901295ef63e2ca

41 files changed, 5627 insertions, 0 deletions

diff --git a/src/main/java/com/android/volley/AuthFailureError.java b/src/main/java/com/android/volley/AuthFailureError.java
new file mode 100644
index 0000000..7bb2e15
--- /dev/null
+++ b/src/main/java/com/android/volley/AuthFailureError.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.content.Intent;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.VolleyError;
+
+/**
+ * Error indicating that there was an authentication failure when performing a Request.
+ */
+@SuppressWarnings("serial")
+public class AuthFailureError extends VolleyError {
+    /** An intent that can be used to resolve this exception. (Brings up the password dialog.) */
+    private Intent mResolutionIntent;
+
+    public AuthFailureError() { }
+
+    public AuthFailureError(Intent intent) {
+        mResolutionIntent = intent;
+    }
+
+    public AuthFailureError(NetworkResponse response) {
+        super(response);
+    }
+
+    public AuthFailureError(String message) {
+        super(message);
+    }
+
+    public AuthFailureError(String message, Exception reason) {
+        super(message, reason);
+    }
+
+    public Intent getResolutionIntent() {
+        return mResolutionIntent;
+    }
+
+    @Override
+    public String getMessage() {
+        if (mResolutionIntent != null) {
+            return "User needs to (re)enter credentials.";
+        }
+        return super.getMessage();
+    }
+}
diff --git a/src/main/java/com/android/volley/Cache.java b/src/main/java/com/android/volley/Cache.java
new file mode 100644
index 0000000..eafd118
--- /dev/null
+++ b/src/main/java/com/android/volley/Cache.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import java.util.Collections;
+import java.util.Map;
+
+/**
+ * An interface for a cache keyed by a String with a byte array as data.
+ */
+public interface Cache {
+    /**
+     * Retrieves an entry from the cache.
+     * @param key Cache key
+     * @return An {@link Entry} or null in the event of a cache miss
+     */
+    public Entry get(String key);
+
+    /**
+     * Adds or replaces an entry to the cache.
+     * @param key Cache key
+     * @param entry Data to store and metadata for cache coherency, TTL, etc.
+     */
+    public void put(String key, Entry entry);
+
+    /**
+     * Performs any potentially long-running actions needed to initialize the cache;
+     * will be called from a worker thread.
+     */
+    public void initialize();
+
+    /**
+     * Invalidates an entry in the cache.
+     * @param key Cache key
+     * @param fullExpire True to fully expire the entry, false to soft expire
+     */
+    public void invalidate(String key, boolean fullExpire);
+
+    /**
+     * Removes an entry from the cache.
+     * @param key Cache key
+     */
+    public void remove(String key);
+
+    /**
+     * Empties the cache.
+     */
+    public void clear();
+
+    /**
+     * Data and metadata for an entry returned by the cache.
+     */
+    public static class Entry {
+        /** The data returned from cache. */
+        public byte[] data;
+
+        /** ETag for cache coherency. */
+        public String etag;
+
+        /** Date of this response as reported by the server. */
+        public long serverDate;
+
+        /** TTL for this record. */
+        public long ttl;
+
+        /** Soft TTL for this record. */
+        public long softTtl;
+
+        /** Immutable response headers as received from server; must be non-null. */
+        public Map<String, String> responseHeaders = Collections.emptyMap();
+
+        /** True if the entry is expired. */
+        public boolean isExpired() {
+            return this.ttl < System.currentTimeMillis();
+        }
+
+        /** True if a refresh is needed from the original data source. */
+        public boolean refreshNeeded() {
+            return this.softTtl < System.currentTimeMillis();
+        }
+    }
+
+}
diff --git a/src/main/java/com/android/volley/CacheDispatcher.java b/src/main/java/com/android/volley/CacheDispatcher.java
new file mode 100644
index 0000000..18d219b
--- /dev/null
+++ b/src/main/java/com/android/volley/CacheDispatcher.java
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.os.Process;
+
+import java.util.concurrent.BlockingQueue;
+
+/**
+ * Provides a thread for performing cache triage on a queue of requests.
+ *
+ * Requests added to the specified cache queue are resolved from cache.
+ * Any deliverable response is posted back to the caller via a
+ * {@link ResponseDelivery}.  Cache misses and responses that require
+ * refresh are enqueued on the specified network queue for processing
+ * by a {@link NetworkDispatcher}.
+ */
+public class CacheDispatcher extends Thread {
+
+    private static final boolean DEBUG = VolleyLog.DEBUG;
+
+    /** The queue of requests coming in for triage. */
+    private final BlockingQueue<Request<?>> mCacheQueue;
+
+    /** The queue of requests going out to the network. */
+    private final BlockingQueue<Request<?>> mNetworkQueue;
+
+    /** The cache to read from. */
+    private final Cache mCache;
+
+    /** For posting responses. */
+    private final ResponseDelivery mDelivery;
+
+    /** Used for telling us to die. */
+    private volatile boolean mQuit = false;
+
+    /**
+     * Creates a new cache triage dispatcher thread.  You must call {@link #start()}
+     * in order to begin processing.
+     *
+     * @param cacheQueue Queue of incoming requests for triage
+     * @param networkQueue Queue to post requests that require network to
+     * @param cache Cache interface to use for resolution
+     * @param delivery Delivery interface to use for posting responses
+     */
+    public CacheDispatcher(
+            BlockingQueue<Request<?>> cacheQueue, BlockingQueue<Request<?>> networkQueue,
+            Cache cache, ResponseDelivery delivery) {
+        mCacheQueue = cacheQueue;
+        mNetworkQueue = networkQueue;
+        mCache = cache;
+        mDelivery = delivery;
+    }
+
+    /**
+     * Forces this dispatcher to quit immediately.  If any requests are still in
+     * the queue, they are not guaranteed to be processed.
+     */
+    public void quit() {
+        mQuit = true;
+        interrupt();
+    }
+
+    @Override
+    public void run() {
+        if (DEBUG) VolleyLog.v("start new dispatcher");
+        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
+
+        // Make a blocking call to initialize the cache.
+        mCache.initialize();
+
+        while (true) {
+            try {
+                // Get a request from the cache triage queue, blocking until
+                // at least one is available.
+                final Request<?> request = mCacheQueue.take();
+                request.addMarker("cache-queue-take");
+
+                // If the request has been canceled, don't bother dispatching it.
+                if (request.isCanceled()) {
+                    request.finish("cache-discard-canceled");
+                    continue;
+                }
+
+                // Attempt to retrieve this item from cache.
+                Cache.Entry entry = mCache.get(request.getCacheKey());
+                if (entry == null) {
+                    request.addMarker("cache-miss");
+                    // Cache miss; send off to the network dispatcher.
+                    mNetworkQueue.put(request);
+                    continue;
+                }
+
+                // If it is completely expired, just send it to the network.
+                if (entry.isExpired()) {
+                    request.addMarker("cache-hit-expired");
+                    request.setCacheEntry(entry);
+                    mNetworkQueue.put(request);
+                    continue;
+                }
+
+                // We have a cache hit; parse its data for delivery back to the request.
+                request.addMarker("cache-hit");
+                Response<?> response = request.parseNetworkResponse(
+                        new NetworkResponse(entry.data, entry.responseHeaders));
+                request.addMarker("cache-hit-parsed");
+
+                if (!entry.refreshNeeded()) {
+                    // Completely unexpired cache hit. Just deliver the response.
+                    mDelivery.postResponse(request, response);
+                } else {
+                    // Soft-expired cache hit. We can deliver the cached response,
+                    // but we need to also send the request to the network for
+                    // refreshing.
+                    request.addMarker("cache-hit-refresh-needed");
+                    request.setCacheEntry(entry);
+
+                    // Mark the response as intermediate.
+                    response.intermediate = true;
+
+                    // Post the intermediate response back to the user and have
+                    // the delivery then forward the request along to the network.
+                    mDelivery.postResponse(request, response, new Runnable() {
+                        @Override
+                        public void run() {
+                            try {
+                                mNetworkQueue.put(request);
+                            } catch (InterruptedException e) {
+                                // Not much we can do about this.
+                            }
+                        }
+                    });
+                }
+
+            } catch (InterruptedException e) {
+                // We may have been interrupted because it was time to quit.
+                if (mQuit) {
+                    return;
+                }
+                continue;
+            }
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/DefaultRetryPolicy.java b/src/main/java/com/android/volley/DefaultRetryPolicy.java
new file mode 100644
index 0000000..d8abab0
--- /dev/null
+++ b/src/main/java/com/android/volley/DefaultRetryPolicy.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Default retry policy for requests.
+ */
+public class DefaultRetryPolicy implements RetryPolicy {
+    /** The current timeout in milliseconds. */
+    private int mCurrentTimeoutMs;
+
+    /** The current retry count. */
+    private int mCurrentRetryCount;
+
+    /** The maximum number of attempts. */
+    private final int mMaxNumRetries;
+
+    /** The backoff multiplier for the policy. */
+    private final float mBackoffMultiplier;
+
+    /** The default socket timeout in milliseconds */
+    public static final int DEFAULT_TIMEOUT_MS = 2500;
+
+    /** The default number of retries */
+    public static final int DEFAULT_MAX_RETRIES = 1;
+
+    /** The default backoff multiplier */
+    public static final float DEFAULT_BACKOFF_MULT = 1f;
+
+    /**
+     * Constructs a new retry policy using the default timeouts.
+     */
+    public DefaultRetryPolicy() {
+        this(DEFAULT_TIMEOUT_MS, DEFAULT_MAX_RETRIES, DEFAULT_BACKOFF_MULT);
+    }
+
+    /**
+     * Constructs a new retry policy.
+     * @param initialTimeoutMs The initial timeout for the policy.
+     * @param maxNumRetries The maximum number of retries.
+     * @param backoffMultiplier Backoff multiplier for the policy.
+     */
+    public DefaultRetryPolicy(int initialTimeoutMs, int maxNumRetries, float backoffMultiplier) {
+        mCurrentTimeoutMs = initialTimeoutMs;
+        mMaxNumRetries = maxNumRetries;
+        mBackoffMultiplier = backoffMultiplier;
+    }
+
+    /**
+     * Returns the current timeout.
+     */
+    @Override
+    public int getCurrentTimeout() {
+        return mCurrentTimeoutMs;
+    }
+
+    /**
+     * Returns the current retry count.
+     */
+    @Override
+    public int getCurrentRetryCount() {
+        return mCurrentRetryCount;
+    }
+
+    /**
+     * Returns the backoff multiplier for the policy.
+     */
+    public float getBackoffMultiplier() {
+        return mBackoffMultiplier;
+    }
+
+    /**
+     * Prepares for the next retry by applying a backoff to the timeout.
+     * @param error The error code of the last attempt.
+     */
+    @Override
+    public void retry(VolleyError error) throws VolleyError {
+        mCurrentRetryCount++;
+        mCurrentTimeoutMs += (mCurrentTimeoutMs * mBackoffMultiplier);
+        if (!hasAttemptRemaining()) {
+            throw error;
+        }
+    }
+
+    /**
+     * Returns true if this policy has attempts remaining, false otherwise.
+     */
+    protected boolean hasAttemptRemaining() {
+        return mCurrentRetryCount <= mMaxNumRetries;
+    }
+}
diff --git a/src/main/java/com/android/volley/ExecutorDelivery.java b/src/main/java/com/android/volley/ExecutorDelivery.java
new file mode 100644
index 0000000..1babfcd
--- /dev/null
+++ b/src/main/java/com/android/volley/ExecutorDelivery.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.os.Handler;
+
+import java.util.concurrent.Executor;
+
+/**
+ * Delivers responses and errors.
+ */
+public class ExecutorDelivery implements ResponseDelivery {
+    /** Used for posting responses, typically to the main thread. */
+    private final Executor mResponsePoster;
+
+    /**
+     * Creates a new response delivery interface.
+     * @param handler {@link Handler} to post responses on
+     */
+    public ExecutorDelivery(final Handler handler) {
+        // Make an Executor that just wraps the handler.
+        mResponsePoster = new Executor() {
+            @Override
+            public void execute(Runnable command) {
+                handler.post(command);
+            }
+        };
+    }
+
+    /**
+     * Creates a new response delivery interface, mockable version
+     * for testing.
+     * @param executor For running delivery tasks
+     */
+    public ExecutorDelivery(Executor executor) {
+        mResponsePoster = executor;
+    }
+
+    @Override
+    public void postResponse(Request<?> request, Response<?> response) {
+        postResponse(request, response, null);
+    }
+
+    @Override
+    public void postResponse(Request<?> request, Response<?> response, Runnable runnable) {
+        request.markDelivered();
+        request.addMarker("post-response");
+        mResponsePoster.execute(new ResponseDeliveryRunnable(request, response, runnable));
+    }
+
+    @Override
+    public void postError(Request<?> request, VolleyError error) {
+        request.addMarker("post-error");
+        Response<?> response = Response.error(error);
+        mResponsePoster.execute(new ResponseDeliveryRunnable(request, response, null));
+    }
+
+    /**
+     * A Runnable used for delivering network responses to a listener on the
+     * main thread.
+     */
+    @SuppressWarnings("rawtypes")
+    private class ResponseDeliveryRunnable implements Runnable {
+        private final Request mRequest;
+        private final Response mResponse;
+        private final Runnable mRunnable;
+
+        public ResponseDeliveryRunnable(Request request, Response response, Runnable runnable) {
+            mRequest = request;
+            mResponse = response;
+            mRunnable = runnable;
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public void run() {
+            // If this request has canceled, finish it and don't deliver.
+            if (mRequest.isCanceled()) {
+                mRequest.finish("canceled-at-delivery");
+                return;
+            }
+
+            // Deliver a normal response or error, depending.
+            if (mResponse.isSuccess()) {
+                mRequest.deliverResponse(mResponse.result);
+            } else {
+                mRequest.deliverError(mResponse.error);
+            }
+
+            // If this is an intermediate response, add a marker, otherwise we're done
+            // and the request can be finished.
+            if (mResponse.intermediate) {
+                mRequest.addMarker("intermediate-response");
+            } else {
+                mRequest.finish("done");
+            }
+
+            // If we have been provided a post-delivery runnable, run it.
+            if (mRunnable != null) {
+                mRunnable.run();
+            }
+       }
+    }
+}
diff --git a/src/main/java/com/android/volley/Network.java b/src/main/java/com/android/volley/Network.java
new file mode 100644
index 0000000..ab45830
--- /dev/null
+++ b/src/main/java/com/android/volley/Network.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * An interface for performing requests.
+ */
+public interface Network {
+    /**
+     * Performs the specified request.
+     * @param request Request to process
+     * @return A {@link NetworkResponse} with data and caching metadata; will never be null
+     * @throws VolleyError on errors
+     */
+    public NetworkResponse performRequest(Request<?> request) throws VolleyError;
+}
diff --git a/src/main/java/com/android/volley/NetworkDispatcher.java b/src/main/java/com/android/volley/NetworkDispatcher.java
new file mode 100644
index 0000000..beb7861
--- /dev/null
+++ b/src/main/java/com/android/volley/NetworkDispatcher.java
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.annotation.TargetApi;
+import android.net.TrafficStats;
+import android.os.Build;
+import android.os.Process;
+import android.os.SystemClock;
+
+import java.util.concurrent.BlockingQueue;
+
+/**
+ * Provides a thread for performing network dispatch from a queue of requests.
+ *
+ * Requests added to the specified queue are processed from the network via a
+ * specified {@link Network} interface. Responses are committed to cache, if
+ * eligible, using a specified {@link Cache} interface. Valid responses and
+ * errors are posted back to the caller via a {@link ResponseDelivery}.
+ */
+public class NetworkDispatcher extends Thread {
+    /** The queue of requests to service. */
+    private final BlockingQueue<Request<?>> mQueue;
+    /** The network interface for processing requests. */
+    private final Network mNetwork;
+    /** The cache to write to. */
+    private final Cache mCache;
+    /** For posting responses and errors. */
+    private final ResponseDelivery mDelivery;
+    /** Used for telling us to die. */
+    private volatile boolean mQuit = false;
+
+    /**
+     * Creates a new network dispatcher thread.  You must call {@link #start()}
+     * in order to begin processing.
+     *
+     * @param queue Queue of incoming requests for triage
+     * @param network Network interface to use for performing requests
+     * @param cache Cache interface to use for writing responses to cache
+     * @param delivery Delivery interface to use for posting responses
+     */
+    public NetworkDispatcher(BlockingQueue<Request<?>> queue,
+            Network network, Cache cache,
+            ResponseDelivery delivery) {
+        mQueue = queue;
+        mNetwork = network;
+        mCache = cache;
+        mDelivery = delivery;
+    }
+
+    /**
+     * Forces this dispatcher to quit immediately.  If any requests are still in
+     * the queue, they are not guaranteed to be processed.
+     */
+    public void quit() {
+        mQuit = true;
+        interrupt();
+    }
+
+    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
+    private void addTrafficStatsTag(Request<?> request) {
+        // Tag the request (if API >= 14)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
+            TrafficStats.setThreadStatsTag(request.getTrafficStatsTag());
+        }
+    }
+
+    @Override
+    public void run() {
+        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
+        while (true) {
+            long startTimeMs = SystemClock.elapsedRealtime();
+            Request<?> request;
+            try {
+                // Take a request from the queue.
+                request = mQueue.take();
+            } catch (InterruptedException e) {
+                // We may have been interrupted because it was time to quit.
+                if (mQuit) {
+                    return;
+                }
+                continue;
+            }
+
+            try {
+                request.addMarker("network-queue-take");
+
+                // If the request was cancelled already, do not perform the
+                // network request.
+                if (request.isCanceled()) {
+                    request.finish("network-discard-cancelled");
+                    continue;
+                }
+
+                addTrafficStatsTag(request);
+
+                // Perform the network request.
+                NetworkResponse networkResponse = mNetwork.performRequest(request);
+                request.addMarker("network-http-complete");
+
+                // If the server returned 304 AND we delivered a response already,
+                // we're done -- don't deliver a second identical response.
+                if (networkResponse.notModified && request.hasHadResponseDelivered()) {
+                    request.finish("not-modified");
+                    continue;
+                }
+
+                // Parse the response here on the worker thread.
+                Response<?> response = request.parseNetworkResponse(networkResponse);
+                request.addMarker("network-parse-complete");
+
+                // Write to cache if applicable.
+                // TODO: Only update cache metadata instead of entire record for 304s.
+                if (request.shouldCache() && response.cacheEntry != null) {
+                    mCache.put(request.getCacheKey(), response.cacheEntry);
+                    request.addMarker("network-cache-written");
+                }
+
+                // Post the response back.
+                request.markDelivered();
+                mDelivery.postResponse(request, response);
+            } catch (VolleyError volleyError) {
+                volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);
+                parseAndDeliverNetworkError(request, volleyError);
+            } catch (Exception e) {
+                VolleyLog.e(e, "Unhandled exception %s", e.toString());
+                VolleyError volleyError = new VolleyError(e);
+                volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);
+                mDelivery.postError(request, volleyError);
+            }
+        }
+    }
+
+    private void parseAndDeliverNetworkError(Request<?> request, VolleyError error) {
+        error = request.parseNetworkError(error);
+        mDelivery.postError(request, error);
+    }
+}
diff --git a/src/main/java/com/android/volley/NetworkError.java b/src/main/java/com/android/volley/NetworkError.java
new file mode 100644
index 0000000..42fbcc2
--- /dev/null
+++ b/src/main/java/com/android/volley/NetworkError.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.VolleyError;
+
+/**
+ * Indicates that there was a network error when performing a Volley request.
+ */
+@SuppressWarnings("serial")
+public class NetworkError extends VolleyError {
+    public NetworkError() {
+        super();
+    }
+
+    public NetworkError(Throwable cause) {
+        super(cause);
+    }
+
+    public NetworkError(NetworkResponse networkResponse) {
+        super(networkResponse);
+    }
+}
diff --git a/src/main/java/com/android/volley/NetworkResponse.java b/src/main/java/com/android/volley/NetworkResponse.java
new file mode 100644
index 0000000..a787fa7
--- /dev/null
+++ b/src/main/java/com/android/volley/NetworkResponse.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import org.apache.http.HttpStatus;
+
+import java.util.Collections;
+import java.util.Map;
+
+/**
+ * Data and headers returned from {@link Network#performRequest(Request)}.
+ */
+public class NetworkResponse {
+    /**
+     * Creates a new network response.
+     * @param statusCode the HTTP status code
+     * @param data Response body
+     * @param headers Headers returned with this response, or null for none
+     * @param notModified True if the server returned a 304 and the data was already in cache
+     * @param networkTimeMs Round-trip network time to receive network response
+     */
+    public NetworkResponse(int statusCode, byte[] data, Map<String, String> headers,
+            boolean notModified, long networkTimeMs) {
+        this.statusCode = statusCode;
+        this.data = data;
+        this.headers = headers;
+        this.notModified = notModified;
+        this.networkTimeMs = networkTimeMs;
+    }
+
+    public NetworkResponse(int statusCode, byte[] data, Map<String, String> headers,
+            boolean notModified) {
+        this(statusCode, data, headers, notModified, 0);
+    }
+
+    public NetworkResponse(byte[] data) {
+        this(HttpStatus.SC_OK, data, Collections.<String, String>emptyMap(), false, 0);
+    }
+
+    public NetworkResponse(byte[] data, Map<String, String> headers) {
+        this(HttpStatus.SC_OK, data, headers, false, 0);
+    }
+
+    /** The HTTP status code. */
+    public final int statusCode;
+
+    /** Raw data from this response. */
+    public final byte[] data;
+
+    /** Response headers. */
+    public final Map<String, String> headers;
+
+    /** True if the server returned a 304 (Not Modified). */
+    public final boolean notModified;
+
+    /** Network roundtrip time in milliseconds. */
+    public final long networkTimeMs;
+}
+
diff --git a/src/main/java/com/android/volley/NoConnectionError.java b/src/main/java/com/android/volley/NoConnectionError.java
new file mode 100644
index 0000000..fc23156
--- /dev/null
+++ b/src/main/java/com/android/volley/NoConnectionError.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Error indicating that no connection could be established when performing a Volley request.
+ */
+@SuppressWarnings("serial")
+public class NoConnectionError extends NetworkError {
+    public NoConnectionError() {
+        super();
+    }
+
+    public NoConnectionError(Throwable reason) {
+        super(reason);
+    }
+}
diff --git a/src/main/java/com/android/volley/ParseError.java b/src/main/java/com/android/volley/ParseError.java
new file mode 100644
index 0000000..a55da47
--- /dev/null
+++ b/src/main/java/com/android/volley/ParseError.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.VolleyError;
+
+/**
+ * Indicates that the server's response could not be parsed.
+ */
+@SuppressWarnings("serial")
+public class ParseError extends VolleyError {
+    public ParseError() { }
+
+    public ParseError(NetworkResponse networkResponse) {
+        super(networkResponse);
+    }
+
+    public ParseError(Throwable cause) {
+        super(cause);
+    }
+}
diff --git a/src/main/java/com/android/volley/Request.java b/src/main/java/com/android/volley/Request.java
new file mode 100644
index 0000000..9832952
--- /dev/null
+++ b/src/main/java/com/android/volley/Request.java
@@ -0,0 +1,603 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.net.TrafficStats;
+import android.net.Uri;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.SystemClock;
+import android.text.TextUtils;
+
+import com.android.volley.VolleyLog.MarkerLog;
+
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.Collections;
+import java.util.Map;
+
+/**
+ * Base class for all network requests.
+ *
+ * @param <T> The type of parsed response this request expects.
+ */
+public abstract class Request<T> implements Comparable<Request<T>> {
+
+    /**
+     * Default encoding for POST or PUT parameters. See {@link #getParamsEncoding()}.
+     */
+    private static final String DEFAULT_PARAMS_ENCODING = "UTF-8";
+
+    /**
+     * Supported request methods.
+     */
+    public interface Method {
+        int DEPRECATED_GET_OR_POST = -1;
+        int GET = 0;
+        int POST = 1;
+        int PUT = 2;
+        int DELETE = 3;
+        int HEAD = 4;
+        int OPTIONS = 5;
+        int TRACE = 6;
+        int PATCH = 7;
+    }
+
+    /** An event log tracing the lifetime of this request; for debugging. */
+    private final MarkerLog mEventLog = MarkerLog.ENABLED ? new MarkerLog() : null;
+
+    /**
+     * Request method of this request.  Currently supports GET, POST, PUT, DELETE, HEAD, OPTIONS,
+     * TRACE, and PATCH.
+     */
+    private final int mMethod;
+
+    /** URL of this request. */
+    private final String mUrl;
+
+    /** Default tag for {@link TrafficStats}. */
+    private final int mDefaultTrafficStatsTag;
+
+    /** Listener interface for errors. */
+    private final Response.ErrorListener mErrorListener;
+
+    /** Sequence number of this request, used to enforce FIFO ordering. */
+    private Integer mSequence;
+
+    /** The request queue this request is associated with. */
+    private RequestQueue mRequestQueue;
+
+    /** Whether or not responses to this request should be cached. */
+    private boolean mShouldCache = true;
+
+    /** Whether or not this request has been canceled. */
+    private boolean mCanceled = false;
+
+    /** Whether or not a response has been delivered for this request yet. */
+    private boolean mResponseDelivered = false;
+
+    // A cheap variant of request tracing used to dump slow requests.
+    private long mRequestBirthTime = 0;
+
+    /** Threshold at which we should log the request (even when debug logging is not enabled). */
+    private static final long SLOW_REQUEST_THRESHOLD_MS = 3000;
+
+    /** The retry policy for this request. */
+    private RetryPolicy mRetryPolicy;
+
+    /**
+     * When a request can be retrieved from cache but must be refreshed from
+     * the network, the cache entry will be stored here so that in the event of
+     * a "Not Modified" response, we can be sure it hasn't been evicted from cache.
+     */
+    private Cache.Entry mCacheEntry = null;
+
+    /** An opaque token tagging this request; used for bulk cancellation. */
+    private Object mTag;
+
+    /**
+     * Creates a new request with the given URL and error listener.  Note that
+     * the normal response listener is not provided here as delivery of responses
+     * is provided by subclasses, who have a better idea of how to deliver an
+     * already-parsed response.
+     *
+     * @deprecated Use {@link #Request(int, String, com.android.volley.Response.ErrorListener)}.
+     */
+    @Deprecated
+    public Request(String url, Response.ErrorListener listener) {
+        this(Method.DEPRECATED_GET_OR_POST, url, listener);
+    }
+
+    /**
+     * Creates a new request with the given method (one of the values from {@link Method}),
+     * URL, and error listener.  Note that the normal response listener is not provided here as
+     * delivery of responses is provided by subclasses, who have a better idea of how to deliver
+     * an already-parsed response.
+     */
+    public Request(int method, String url, Response.ErrorListener listener) {
+        mMethod = method;
+        mUrl = url;
+        mErrorListener = listener;
+        setRetryPolicy(new DefaultRetryPolicy());
+
+        mDefaultTrafficStatsTag = findDefaultTrafficStatsTag(url);
+    }
+
+    /**
+     * Return the method for this request.  Can be one of the values in {@link Method}.
+     */
+    public int getMethod() {
+        return mMethod;
+    }
+
+    /**
+     * Set a tag on this request. Can be used to cancel all requests with this
+     * tag by {@link RequestQueue#cancelAll(Object)}.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public Request<?> setTag(Object tag) {
+        mTag = tag;
+        return this;
+    }
+
+    /**
+     * Returns this request's tag.
+     * @see Request#setTag(Object)
+     */
+    public Object getTag() {
+        return mTag;
+    }
+
+    /**
+     * @return this request's {@link com.android.volley.Response.ErrorListener}.
+     */
+    public Response.ErrorListener getErrorListener() {
+        return mErrorListener;
+    }
+
+    /**
+     * @return A tag for use with {@link TrafficStats#setThreadStatsTag(int)}
+     */
+    public int getTrafficStatsTag() {
+        return mDefaultTrafficStatsTag;
+    }
+
+    /**
+     * @return The hashcode of the URL's host component, or 0 if there is none.
+     */
+    private static int findDefaultTrafficStatsTag(String url) {
+        if (!TextUtils.isEmpty(url)) {
+            Uri uri = Uri.parse(url);
+            if (uri != null) {
+                String host = uri.getHost();
+                if (host != null) {
+                    return host.hashCode();
+                }
+            }
+        }
+        return 0;
+    }
+
+    /**
+     * Sets the retry policy for this request.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public Request<?> setRetryPolicy(RetryPolicy retryPolicy) {
+        mRetryPolicy = retryPolicy;
+        return this;
+    }
+
+    /**
+     * Adds an event to this request's event log; for debugging.
+     */
+    public void addMarker(String tag) {
+        if (MarkerLog.ENABLED) {
+            mEventLog.add(tag, Thread.currentThread().getId());
+        } else if (mRequestBirthTime == 0) {
+            mRequestBirthTime = SystemClock.elapsedRealtime();
+        }
+    }
+
+    /**
+     * Notifies the request queue that this request has finished (successfully or with error).
+     *
+     * <p>Also dumps all events from this request's event log; for debugging.</p>
+     */
+    void finish(final String tag) {
+        if (mRequestQueue != null) {
+            mRequestQueue.finish(this);
+        }
+        if (MarkerLog.ENABLED) {
+            final long threadId = Thread.currentThread().getId();
+            if (Looper.myLooper() != Looper.getMainLooper()) {
+                // If we finish marking off of the main thread, we need to
+                // actually do it on the main thread to ensure correct ordering.
+                Handler mainThread = new Handler(Looper.getMainLooper());
+                mainThread.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        mEventLog.add(tag, threadId);
+                        mEventLog.finish(this.toString());
+                    }
+                });
+                return;
+            }
+
+            mEventLog.add(tag, threadId);
+            mEventLog.finish(this.toString());
+        } else {
+            long requestTime = SystemClock.elapsedRealtime() - mRequestBirthTime;
+            if (requestTime >= SLOW_REQUEST_THRESHOLD_MS) {
+                VolleyLog.d("%d ms: %s", requestTime, this.toString());
+            }
+        }
+    }
+
+    /**
+     * Associates this request with the given queue. The request queue will be notified when this
+     * request has finished.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public Request<?> setRequestQueue(RequestQueue requestQueue) {
+        mRequestQueue = requestQueue;
+        return this;
+    }
+
+    /**
+     * Sets the sequence number of this request.  Used by {@link RequestQueue}.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public final Request<?> setSequence(int sequence) {
+        mSequence = sequence;
+        return this;
+    }
+
+    /**
+     * Returns the sequence number of this request.
+     */
+    public final int getSequence() {
+        if (mSequence == null) {
+            throw new IllegalStateException("getSequence called before setSequence");
+        }
+        return mSequence;
+    }
+
+    /**
+     * Returns the URL of this request.
+     */
+    public String getUrl() {
+        return mUrl;
+    }
+
+    /**
+     * Returns the cache key for this request.  By default, this is the URL.
+     */
+    public String getCacheKey() {
+        return getUrl();
+    }
+
+    /**
+     * Annotates this request with an entry retrieved for it from cache.
+     * Used for cache coherency support.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public Request<?> setCacheEntry(Cache.Entry entry) {
+        mCacheEntry = entry;
+        return this;
+    }
+
+    /**
+     * Returns the annotated cache entry, or null if there isn't one.
+     */
+    public Cache.Entry getCacheEntry() {
+        return mCacheEntry;
+    }
+
+    /**
+     * Mark this request as canceled.  No callback will be delivered.
+     */
+    public void cancel() {
+        mCanceled = true;
+    }
+
+    /**
+     * Returns true if this request has been canceled.
+     */
+    public boolean isCanceled() {
+        return mCanceled;
+    }
+
+    /**
+     * Returns a list of extra HTTP headers to go along with this request. Can
+     * throw {@link AuthFailureError} as authentication may be required to
+     * provide these values.
+     * @throws AuthFailureError In the event of auth failure
+     */
+    public Map<String, String> getHeaders() throws AuthFailureError {
+        return Collections.emptyMap();
+    }
+
+    /**
+     * Returns a Map of POST parameters to be used for this request, or null if
+     * a simple GET should be used.  Can throw {@link AuthFailureError} as
+     * authentication may be required to provide these values.
+     *
+     * <p>Note that only one of getPostParams() and getPostBody() can return a non-null
+     * value.</p>
+     * @throws AuthFailureError In the event of auth failure
+     *
+     * @deprecated Use {@link #getParams()} instead.
+     */
+    @Deprecated
+    protected Map<String, String> getPostParams() throws AuthFailureError {
+        return getParams();
+    }
+
+    /**
+     * Returns which encoding should be used when converting POST parameters returned by
+     * {@link #getPostParams()} into a raw POST body.
+     *
+     * <p>This controls both encodings:
+     * <ol>
+     *     <li>The string encoding used when converting parameter names and values into bytes prior
+     *         to URL encoding them.</li>
+     *     <li>The string encoding used when converting the URL encoded parameters into a raw
+     *         byte array.</li>
+     * </ol>
+     *
+     * @deprecated Use {@link #getParamsEncoding()} instead.
+     */
+    @Deprecated
+    protected String getPostParamsEncoding() {
+        return getParamsEncoding();
+    }
+
+    /**
+     * @deprecated Use {@link #getBodyContentType()} instead.
+     */
+    @Deprecated
+    public String getPostBodyContentType() {
+        return getBodyContentType();
+    }
+
+    /**
+     * Returns the raw POST body to be sent.
+     *
+     * @throws AuthFailureError In the event of auth failure
+     *
+     * @deprecated Use {@link #getBody()} instead.
+     */
+    @Deprecated
+    public byte[] getPostBody() throws AuthFailureError {
+        // Note: For compatibility with legacy clients of volley, this implementation must remain
+        // here instead of simply calling the getBody() function because this function must
+        // call getPostParams() and getPostParamsEncoding() since legacy clients would have
+        // overridden these two member functions for POST requests.
+        Map<String, String> postParams = getPostParams();
+        if (postParams != null && postParams.size() > 0) {
+            return encodeParameters(postParams, getPostParamsEncoding());
+        }
+        return null;
+    }
+
+    /**
+     * Returns a Map of parameters to be used for a POST or PUT request.  Can throw
+     * {@link AuthFailureError} as authentication may be required to provide these values.
+     *
+     * <p>Note that you can directly override {@link #getBody()} for custom data.</p>
+     *
+     * @throws AuthFailureError in the event of auth failure
+     */
+    protected Map<String, String> getParams() throws AuthFailureError {
+        return null;
+    }
+
+    /**
+     * Returns which encoding should be used when converting POST or PUT parameters returned by
+     * {@link #getParams()} into a raw POST or PUT body.
+     *
+     * <p>This controls both encodings:
+     * <ol>
+     *     <li>The string encoding used when converting parameter names and values into bytes prior
+     *         to URL encoding them.</li>
+     *     <li>The string encoding used when converting the URL encoded parameters into a raw
+     *         byte array.</li>
+     * </ol>
+     */
+    protected String getParamsEncoding() {
+        return DEFAULT_PARAMS_ENCODING;
+    }
+
+    /**
+     * Returns the content type of the POST or PUT body.
+     */
+    public String getBodyContentType() {
+        return "application/x-www-form-urlencoded; charset=" + getParamsEncoding();
+    }
+
+    /**
+     * Returns the raw POST or PUT body to be sent.
+     *
+     * <p>By default, the body consists of the request parameters in
+     * application/x-www-form-urlencoded format. When overriding this method, consider overriding
+     * {@link #getBodyContentType()} as well to match the new body format.
+     *
+     * @throws AuthFailureError in the event of auth failure
+     */
+    public byte[] getBody() throws AuthFailureError {
+        Map<String, String> params = getParams();
+        if (params != null && params.size() > 0) {
+            return encodeParameters(params, getParamsEncoding());
+        }
+        return null;
+    }
+
+    /**
+     * Converts <code>params</code> into an application/x-www-form-urlencoded encoded string.
+     */
+    private byte[] encodeParameters(Map<String, String> params, String paramsEncoding) {
+        StringBuilder encodedParams = new StringBuilder();
+        try {
+            for (Map.Entry<String, String> entry : params.entrySet()) {
+                encodedParams.append(URLEncoder.encode(entry.getKey(), paramsEncoding));
+                encodedParams.append('=');
+                encodedParams.append(URLEncoder.encode(entry.getValue(), paramsEncoding));
+                encodedParams.append('&');
+            }
+            return encodedParams.toString().getBytes(paramsEncoding);
+        } catch (UnsupportedEncodingException uee) {
+            throw new RuntimeException("Encoding not supported: " + paramsEncoding, uee);
+        }
+    }
+
+    /**
+     * Set whether or not responses to this request should be cached.
+     *
+     * @return This Request object to allow for chaining.
+     */
+    public final Request<?> setShouldCache(boolean shouldCache) {
+        mShouldCache = shouldCache;
+        return this;
+    }
+
+    /**
+     * Returns true if responses to this request should be cached.
+     */
+    public final boolean shouldCache() {
+        return mShouldCache;
+    }
+
+    /**
+     * Priority values.  Requests will be processed from higher priorities to
+     * lower priorities, in FIFO order.
+     */
+    public enum Priority {
+        LOW,
+        NORMAL,
+        HIGH,
+        IMMEDIATE
+    }
+
+    /**
+     * Returns the {@link Priority} of this request; {@link Priority#NORMAL} by default.
+     */
+    public Priority getPriority() {
+        return Priority.NORMAL;
+    }
+
+    /**
+     * Returns the socket timeout in milliseconds per retry attempt. (This value can be changed
+     * per retry attempt if a backoff is specified via backoffTimeout()). If there are no retry
+     * attempts remaining, this will cause delivery of a {@link TimeoutError} error.
+     */
+    public final int getTimeoutMs() {
+        return mRetryPolicy.getCurrentTimeout();
+    }
+
+    /**
+     * Returns the retry policy that should be used  for this request.
+     */
+    public RetryPolicy getRetryPolicy() {
+        return mRetryPolicy;
+    }
+
+    /**
+     * Mark this request as having a response delivered on it.  This can be used
+     * later in the request's lifetime for suppressing identical responses.
+     */
+    public void markDelivered() {
+        mResponseDelivered = true;
+    }
+
+    /**
+     * Returns true if this request has had a response delivered for it.
+     */
+    public boolean hasHadResponseDelivered() {
+        return mResponseDelivered;
+    }
+
+    /**
+     * Subclasses must implement this to parse the raw network response
+     * and return an appropriate response type. This method will be
+     * called from a worker thread.  The response will not be delivered
+     * if you return null.
+     * @param response Response from the network
+     * @return The parsed response, or null in the case of an error
+     */
+    abstract protected Response<T> parseNetworkResponse(NetworkResponse response);
+
+    /**
+     * Subclasses can override this method to parse 'networkError' and return a more specific error.
+     *
+     * <p>The default implementation just returns the passed 'networkError'.</p>
+     *
+     * @param volleyError the error retrieved from the network
+     * @return an NetworkError augmented with additional information
+     */
+    protected VolleyError parseNetworkError(VolleyError volleyError) {
+        return volleyError;
+    }
+
+    /**
+     * Subclasses must implement this to perform delivery of the parsed
+     * response to their listeners.  The given response is guaranteed to
+     * be non-null; responses that fail to parse are not delivered.
+     * @param response The parsed response returned by
+     * {@link #parseNetworkResponse(NetworkResponse)}
+     */
+    abstract protected void deliverResponse(T response);
+
+    /**
+     * Delivers error message to the ErrorListener that the Request was
+     * initialized with.
+     *
+     * @param error Error details
+     */
+    public void deliverError(VolleyError error) {
+        if (mErrorListener != null) {
+            mErrorListener.onErrorResponse(error);
+        }
+    }
+
+    /**
+     * Our comparator sorts from high to low priority, and secondarily by
+     * sequence number to provide FIFO ordering.
+     */
+    @Override
+    public int compareTo(Request<T> other) {
+        Priority left = this.getPriority();
+        Priority right = other.getPriority();
+
+        // High-priority requests are "lesser" so they are sorted to the front.
+        // Equal priorities are sorted by sequence number to provide FIFO ordering.
+        return left == right ?
+                this.mSequence - other.mSequence :
+                right.ordinal() - left.ordinal();
+    }
+
+    @Override
+    public String toString() {
+        String trafficStatsTag = "0x" + Integer.toHexString(getTrafficStatsTag());
+        return (mCanceled ? "[X] " : "[ ] ") + getUrl() + " " + trafficStatsTag + " "
+                + getPriority() + " " + mSequence;
+    }
+}
diff --git a/src/main/java/com/android/volley/RequestQueue.java b/src/main/java/com/android/volley/RequestQueue.java
new file mode 100644
index 0000000..5c0e7af
--- /dev/null
+++ b/src/main/java/com/android/volley/RequestQueue.java
@@ -0,0 +1,286 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.os.Handler;
+import android.os.Looper;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Map;
+import java.util.Queue;
+import java.util.Set;
+import java.util.concurrent.PriorityBlockingQueue;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * A request dispatch queue with a thread pool of dispatchers.
+ *
+ * Calling {@link #add(Request)} will enqueue the given Request for dispatch,
+ * resolving from either cache or network on a worker thread, and then delivering
+ * a parsed response on the main thread.
+ */
+public class RequestQueue {
+
+    /** Used for generating monotonically-increasing sequence numbers for requests. */
+    private AtomicInteger mSequenceGenerator = new AtomicInteger();
+
+    /**
+     * Staging area for requests that already have a duplicate request in flight.
+     *
+     * <ul>
+     *     <li>containsKey(cacheKey) indicates that there is a request in flight for the given cache
+     *          key.</li>
+     *     <li>get(cacheKey) returns waiting requests for the given cache key. The in flight request
+     *          is <em>not</em> contained in that list. Is null if no requests are staged.</li>
+     * </ul>
+     */
+    private final Map<String, Queue<Request<?>>> mWaitingRequests =
+            new HashMap<String, Queue<Request<?>>>();
+
+    /**
+     * The set of all requests currently being processed by this RequestQueue. A Request
+     * will be in this set if it is waiting in any queue or currently being processed by
+     * any dispatcher.
+     */
+    private final Set<Request<?>> mCurrentRequests = new HashSet<Request<?>>();
+
+    /** The cache triage queue. */
+    private final PriorityBlockingQueue<Request<?>> mCacheQueue =
+        new PriorityBlockingQueue<Request<?>>();
+
+    /** The queue of requests that are actually going out to the network. */
+    private final PriorityBlockingQueue<Request<?>> mNetworkQueue =
+        new PriorityBlockingQueue<Request<?>>();
+
+    /** Number of network request dispatcher threads to start. */
+    private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE = 4;
+
+    /** Cache interface for retrieving and storing responses. */
+    private final Cache mCache;
+
+    /** Network interface for performing requests. */
+    private final Network mNetwork;
+
+    /** Response delivery mechanism. */
+    private final ResponseDelivery mDelivery;
+
+    /** The network dispatchers. */
+    private NetworkDispatcher[] mDispatchers;
+
+    /** The cache dispatcher. */
+    private CacheDispatcher mCacheDispatcher;
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     * @param threadPoolSize Number of network dispatcher threads to create
+     * @param delivery A ResponseDelivery interface for posting responses and errors
+     */
+    public RequestQueue(Cache cache, Network network, int threadPoolSize,
+            ResponseDelivery delivery) {
+        mCache = cache;
+        mNetwork = network;
+        mDispatchers = new NetworkDispatcher[threadPoolSize];
+        mDelivery = delivery;
+    }
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     * @param threadPoolSize Number of network dispatcher threads to create
+     */
+    public RequestQueue(Cache cache, Network network, int threadPoolSize) {
+        this(cache, network, threadPoolSize,
+                new ExecutorDelivery(new Handler(Looper.getMainLooper())));
+    }
+
+    /**
+     * Creates the worker pool. Processing will not begin until {@link #start()} is called.
+     *
+     * @param cache A Cache to use for persisting responses to disk
+     * @param network A Network interface for performing HTTP requests
+     */
+    public RequestQueue(Cache cache, Network network) {
+        this(cache, network, DEFAULT_NETWORK_THREAD_POOL_SIZE);
+    }
+
+    /**
+     * Starts the dispatchers in this queue.
+     */
+    public void start() {
+        stop();  // Make sure any currently running dispatchers are stopped.
+        // Create the cache dispatcher and start it.
+        mCacheDispatcher = new CacheDispatcher(mCacheQueue, mNetworkQueue, mCache, mDelivery);
+        mCacheDispatcher.start();
+
+        // Create network dispatchers (and corresponding threads) up to the pool size.
+        for (int i = 0; i < mDispatchers.length; i++) {
+            NetworkDispatcher networkDispatcher = new NetworkDispatcher(mNetworkQueue, mNetwork,
+                    mCache, mDelivery);
+            mDispatchers[i] = networkDispatcher;
+            networkDispatcher.start();
+        }
+    }
+
+    /**
+     * Stops the cache and network dispatchers.
+     */
+    public void stop() {
+        if (mCacheDispatcher != null) {
+            mCacheDispatcher.quit();
+        }
+        for (int i = 0; i < mDispatchers.length; i++) {
+            if (mDispatchers[i] != null) {
+                mDispatchers[i].quit();
+            }
+        }
+    }
+
+    /**
+     * Gets a sequence number.
+     */
+    public int getSequenceNumber() {
+        return mSequenceGenerator.incrementAndGet();
+    }
+
+    /**
+     * Gets the {@link Cache} instance being used.
+     */
+    public Cache getCache() {
+        return mCache;
+    }
+
+    /**
+     * A simple predicate or filter interface for Requests, for use by
+     * {@link RequestQueue#cancelAll(RequestFilter)}.
+     */
+    public interface RequestFilter {
+        public boolean apply(Request<?> request);
+    }
+
+    /**
+     * Cancels all requests in this queue for which the given filter applies.
+     * @param filter The filtering function to use
+     */
+    public void cancelAll(RequestFilter filter) {
+        synchronized (mCurrentRequests) {
+            for (Request<?> request : mCurrentRequests) {
+                if (filter.apply(request)) {
+                    request.cancel();
+                }
+            }
+        }
+    }
+
+    /**
+     * Cancels all requests in this queue with the given tag. Tag must be non-null
+     * and equality is by identity.
+     */
+    public void cancelAll(final Object tag) {
+        if (tag == null) {
+            throw new IllegalArgumentException("Cannot cancelAll with a null tag");
+        }
+        cancelAll(new RequestFilter() {
+            @Override
+            public boolean apply(Request<?> request) {
+                return request.getTag() == tag;
+            }
+        });
+    }
+
+    /**
+     * Adds a Request to the dispatch queue.
+     * @param request The request to service
+     * @return The passed-in request
+     */
+    public <T> Request<T> add(Request<T> request) {
+        // Tag the request as belonging to this queue and add it to the set of current requests.
+        request.setRequestQueue(this);
+        synchronized (mCurrentRequests) {
+            mCurrentRequests.add(request);
+        }
+
+        // Process requests in the order they are added.
+        request.setSequence(getSequenceNumber());
+        request.addMarker("add-to-queue");
+
+        // If the request is uncacheable, skip the cache queue and go straight to the network.
+        if (!request.shouldCache()) {
+            mNetworkQueue.add(request);
+            return request;
+        }
+
+        // Insert request into stage if there's already a request with the same cache key in flight.
+        synchronized (mWaitingRequests) {
+            String cacheKey = request.getCacheKey();
+            if (mWaitingRequests.containsKey(cacheKey)) {
+                // There is already a request in flight. Queue up.
+                Queue<Request<?>> stagedRequests = mWaitingRequests.get(cacheKey);
+                if (stagedRequests == null) {
+                    stagedRequests = new LinkedList<Request<?>>();
+                }
+                stagedRequests.add(request);
+                mWaitingRequests.put(cacheKey, stagedRequests);
+                if (VolleyLog.DEBUG) {
+                    VolleyLog.v("Request for cacheKey=%s is in flight, putting on hold.", cacheKey);
+                }
+            } else {
+                // Insert 'null' queue for this cacheKey, indicating there is now a request in
+                // flight.
+                mWaitingRequests.put(cacheKey, null);
+                mCacheQueue.add(request);
+            }
+            return request;
+        }
+    }
+
+    /**
+     * Called from {@link Request#finish(String)}, indicating that processing of the given request
+     * has finished.
+     *
+     * <p>Releases waiting requests for <code>request.getCacheKey()</code> if
+     *      <code>request.shouldCache()</code>.</p>
+     */
+    void finish(Request<?> request) {
+        // Remove from the set of requests currently being processed.
+        synchronized (mCurrentRequests) {
+            mCurrentRequests.remove(request);
+        }
+
+        if (request.shouldCache()) {
+            synchronized (mWaitingRequests) {
+                String cacheKey = request.getCacheKey();
+                Queue<Request<?>> waitingRequests = mWaitingRequests.remove(cacheKey);
+                if (waitingRequests != null) {
+                    if (VolleyLog.DEBUG) {
+                        VolleyLog.v("Releasing %d waiting requests for cacheKey=%s.",
+                                waitingRequests.size(), cacheKey);
+                    }
+                    // Process all queued up requests. They won't be considered as in flight, but
+                    // that's not a problem as the cache has been primed by 'request'.
+                    mCacheQueue.addAll(waitingRequests);
+                }
+            }
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/Response.java b/src/main/java/com/android/volley/Response.java
new file mode 100644
index 0000000..1165595
--- /dev/null
+++ b/src/main/java/com/android/volley/Response.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Encapsulates a parsed response for delivery.
+ *
+ * @param <T> Parsed type of this response
+ */
+public class Response<T> {
+
+    /** Callback interface for delivering parsed responses. */
+    public interface Listener<T> {
+        /** Called when a response is received. */
+        public void onResponse(T response);
+    }
+
+    /** Callback interface for delivering error responses. */
+    public interface ErrorListener {
+        /**
+         * Callback method that an error has been occurred with the
+         * provided error code and optional user-readable message.
+         */
+        public void onErrorResponse(VolleyError error);
+    }
+
+    /** Returns a successful response containing the parsed result. */
+    public static <T> Response<T> success(T result, Cache.Entry cacheEntry) {
+        return new Response<T>(result, cacheEntry);
+    }
+
+    /**
+     * Returns a failed response containing the given error code and an optional
+     * localized message displayed to the user.
+     */
+    public static <T> Response<T> error(VolleyError error) {
+        return new Response<T>(error);
+    }
+
+    /** Parsed response, or null in the case of error. */
+    public final T result;
+
+    /** Cache metadata for this response, or null in the case of error. */
+    public final Cache.Entry cacheEntry;
+
+    /** Detailed error information if <code>errorCode != OK</code>. */
+    public final VolleyError error;
+
+    /** True if this response was a soft-expired one and a second one MAY be coming. */
+    public boolean intermediate = false;
+
+    /**
+     * Returns whether this response is considered successful.
+     */
+    public boolean isSuccess() {
+        return error == null;
+    }
+
+
+    private Response(T result, Cache.Entry cacheEntry) {
+        this.result = result;
+        this.cacheEntry = cacheEntry;
+        this.error = null;
+    }
+
+    private Response(VolleyError error) {
+        this.result = null;
+        this.cacheEntry = null;
+        this.error = error;
+    }
+}
diff --git a/src/main/java/com/android/volley/ResponseDelivery.java b/src/main/java/com/android/volley/ResponseDelivery.java
new file mode 100644
index 0000000..87706af
--- /dev/null
+++ b/src/main/java/com/android/volley/ResponseDelivery.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+public interface ResponseDelivery {
+    /**
+     * Parses a response from the network or cache and delivers it.
+     */
+    public void postResponse(Request<?> request, Response<?> response);
+
+    /**
+     * Parses a response from the network or cache and delivers it. The provided
+     * Runnable will be executed after delivery.
+     */
+    public void postResponse(Request<?> request, Response<?> response, Runnable runnable);
+
+    /**
+     * Posts an error for the given request.
+     */
+    public void postError(Request<?> request, VolleyError error);
+}
diff --git a/src/main/java/com/android/volley/RetryPolicy.java b/src/main/java/com/android/volley/RetryPolicy.java
new file mode 100644
index 0000000..0dd198b
--- /dev/null
+++ b/src/main/java/com/android/volley/RetryPolicy.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Retry policy for a request.
+ */
+public interface RetryPolicy {
+
+    /**
+     * Returns the current timeout (used for logging).
+     */
+    public int getCurrentTimeout();
+
+    /**
+     * Returns the current retry count (used for logging).
+     */
+    public int getCurrentRetryCount();
+
+    /**
+     * Prepares for the next retry by applying a backoff to the timeout.
+     * @param error The error code of the last attempt.
+     * @throws VolleyError In the event that the retry could not be performed (for example if we
+     * ran out of attempts), the passed in error is thrown.
+     */
+    public void retry(VolleyError error) throws VolleyError;
+}
diff --git a/src/main/java/com/android/volley/ServerError.java b/src/main/java/com/android/volley/ServerError.java
new file mode 100644
index 0000000..70a9fd5
--- /dev/null
+++ b/src/main/java/com/android/volley/ServerError.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.VolleyError;
+
+/**
+ * Indicates that the server responded with an error response.
+ */
+@SuppressWarnings("serial")
+public class ServerError extends VolleyError {
+    public ServerError(NetworkResponse networkResponse) {
+        super(networkResponse);
+    }
+
+    public ServerError() {
+        super();
+    }
+}
diff --git a/src/main/java/com/android/volley/TimeoutError.java b/src/main/java/com/android/volley/TimeoutError.java
new file mode 100644
index 0000000..0b5d6ac
--- /dev/null
+++ b/src/main/java/com/android/volley/TimeoutError.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Indicates that the connection or the socket timed out.
+ */
+@SuppressWarnings("serial")
+public class TimeoutError extends VolleyError { }
diff --git a/src/main/java/com/android/volley/VolleyError.java b/src/main/java/com/android/volley/VolleyError.java
new file mode 100644
index 0000000..1471d40
--- /dev/null
+++ b/src/main/java/com/android/volley/VolleyError.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+/**
+ * Exception style class encapsulating Volley errors
+ */
+@SuppressWarnings("serial")
+public class VolleyError extends Exception {
+    public final NetworkResponse networkResponse;
+    private long networkTimeMs;
+
+    public VolleyError() {
+        networkResponse = null;
+    }
+
+    public VolleyError(NetworkResponse response) {
+        networkResponse = response;
+    }
+
+    public VolleyError(String exceptionMessage) {
+       super(exceptionMessage);
+       networkResponse = null;
+    }
+
+    public VolleyError(String exceptionMessage, Throwable reason) {
+        super(exceptionMessage, reason);
+        networkResponse = null;
+    }
+
+    public VolleyError(Throwable cause) {
+        super(cause);
+        networkResponse = null;
+    }
+
+    /* package */ void setNetworkTimeMs(long networkTimeMs) {
+       this.networkTimeMs = networkTimeMs;
+    }
+
+    public long getNetworkTimeMs() {
+       return networkTimeMs;
+    }
+}
diff --git a/src/main/java/com/android/volley/VolleyLog.java b/src/main/java/com/android/volley/VolleyLog.java
new file mode 100644
index 0000000..6684690
--- /dev/null
+++ b/src/main/java/com/android/volley/VolleyLog.java
@@ -0,0 +1,176 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley;
+
+import android.os.SystemClock;
+import android.util.Log;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+/** Logging helper class. */
+public class VolleyLog {
+    public static String TAG = "Volley";
+
+    public static boolean DEBUG = Log.isLoggable(TAG, Log.VERBOSE);
+
+    /**
+     * Customize the log tag for your application, so that other apps
+     * using Volley don't mix their logs with yours.
+     * <br />
+     * Enable the log property for your tag before starting your app:
+     * <br />
+     * {@code adb shell setprop log.tag.&lt;tag&gt;}
+     */
+    public static void setTag(String tag) {
+        d("Changing log tag to %s", tag);
+        TAG = tag;
+
+        // Reinitialize the DEBUG "constant"
+        DEBUG = Log.isLoggable(TAG, Log.VERBOSE);
+    }
+
+    public static void v(String format, Object... args) {
+        if (DEBUG) {
+            Log.v(TAG, buildMessage(format, args));
+        }
+    }
+
+    public static void d(String format, Object... args) {
+        Log.d(TAG, buildMessage(format, args));
+    }
+
+    public static void e(String format, Object... args) {
+        Log.e(TAG, buildMessage(format, args));
+    }
+
+    public static void e(Throwable tr, String format, Object... args) {
+        Log.e(TAG, buildMessage(format, args), tr);
+    }
+
+    public static void wtf(String format, Object... args) {
+        Log.wtf(TAG, buildMessage(format, args));
+    }
+
+    public static void wtf(Throwable tr, String format, Object... args) {
+        Log.wtf(TAG, buildMessage(format, args), tr);
+    }
+
+    /**
+     * Formats the caller's provided message and prepends useful info like
+     * calling thread ID and method name.
+     */
+    private static String buildMessage(String format, Object... args) {
+        String msg = (args == null) ? format : String.format(Locale.US, format, args);
+        StackTraceElement[] trace = new Throwable().fillInStackTrace().getStackTrace();
+
+        String caller = "<unknown>";
+        // Walk up the stack looking for the first caller outside of VolleyLog.
+        // It will be at least two frames up, so start there.
+        for (int i = 2; i < trace.length; i++) {
+            Class<?> clazz = trace[i].getClass();
+            if (!clazz.equals(VolleyLog.class)) {
+                String callingClass = trace[i].getClassName();
+                callingClass = callingClass.substring(callingClass.lastIndexOf('.') + 1);
+                callingClass = callingClass.substring(callingClass.lastIndexOf('$') + 1);
+
+                caller = callingClass + "." + trace[i].getMethodName();
+                break;
+            }
+        }
+        return String.format(Locale.US, "[%d] %s: %s",
+                Thread.currentThread().getId(), caller, msg);
+    }
+
+    /**
+     * A simple event log with records containing a name, thread ID, and timestamp.
+     */
+    static class MarkerLog {
+        public static final boolean ENABLED = VolleyLog.DEBUG;
+
+        /** Minimum duration from first marker to last in an marker log to warrant logging. */
+        private static final long MIN_DURATION_FOR_LOGGING_MS = 0;
+
+        private static class Marker {
+            public final String name;
+            public final long thread;
+            public final long time;
+
+            public Marker(String name, long thread, long time) {
+                this.name = name;
+                this.thread = thread;
+                this.time = time;
+            }
+        }
+
+        private final List<Marker> mMarkers = new ArrayList<Marker>();
+        private boolean mFinished = false;
+
+        /** Adds a marker to this log with the specified name. */
+        public synchronized void add(String name, long threadId) {
+            if (mFinished) {
+                throw new IllegalStateException("Marker added to finished log");
+            }
+
+            mMarkers.add(new Marker(name, threadId, SystemClock.elapsedRealtime()));
+        }
+
+        /**
+         * Closes the log, dumping it to logcat if the time difference between
+         * the first and last markers is greater than {@link #MIN_DURATION_FOR_LOGGING_MS}.
+         * @param header Header string to print above the marker log.
+         */
+        public synchronized void finish(String header) {
+            mFinished = true;
+
+            long duration = getTotalDuration();
+            if (duration <= MIN_DURATION_FOR_LOGGING_MS) {
+                return;
+            }
+
+            long prevTime = mMarkers.get(0).time;
+            d("(%-4d ms) %s", duration, header);
+            for (Marker marker : mMarkers) {
+                long thisTime = marker.time;
+                d("(+%-4d) [%2d] %s", (thisTime - prevTime), marker.thread, marker.name);
+                prevTime = thisTime;
+            }
+        }
+
+        @Override
+        protected void finalize() throws Throwable {
+            // Catch requests that have been collected (and hence end-of-lifed)
+            // but had no debugging output printed for them.
+            if (!mFinished) {
+                finish("Request on the loose");
+                e("Marker log finalized without finish() - uncaught exit point for request");
+            }
+        }
+
+        /** Returns the time difference between the first and last events in this log. */
+        private long getTotalDuration() {
+            if (mMarkers.size() == 0) {
+                return 0;
+            }
+
+            long first = mMarkers.get(0).time;
+            long last = mMarkers.get(mMarkers.size() - 1).time;
+            return last - first;
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/AndroidAuthenticator.java b/src/main/java/com/android/volley/toolbox/AndroidAuthenticator.java
new file mode 100644
index 0000000..371fd83
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/AndroidAuthenticator.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.AuthFailureError;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.accounts.AccountManagerFuture;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+
+/**
+ * An Authenticator that uses {@link AccountManager} to get auth
+ * tokens of a specified type for a specified account.
+ */
+public class AndroidAuthenticator implements Authenticator {
+    private final Context mContext;
+    private final Account mAccount;
+    private final String mAuthTokenType;
+    private final boolean mNotifyAuthFailure;
+
+    /**
+     * Creates a new authenticator.
+     * @param context Context for accessing AccountManager
+     * @param account Account to authenticate as
+     * @param authTokenType Auth token type passed to AccountManager
+     */
+    public AndroidAuthenticator(Context context, Account account, String authTokenType) {
+        this(context, account, authTokenType, false);
+    }
+
+    /**
+     * Creates a new authenticator.
+     * @param context Context for accessing AccountManager
+     * @param account Account to authenticate as
+     * @param authTokenType Auth token type passed to AccountManager
+     * @param notifyAuthFailure Whether to raise a notification upon auth failure
+     */
+    public AndroidAuthenticator(Context context, Account account, String authTokenType,
+            boolean notifyAuthFailure) {
+        mContext = context;
+        mAccount = account;
+        mAuthTokenType = authTokenType;
+        mNotifyAuthFailure = notifyAuthFailure;
+    }
+
+    /**
+     * Returns the Account being used by this authenticator.
+     */
+    public Account getAccount() {
+        return mAccount;
+    }
+
+    // TODO: Figure out what to do about notifyAuthFailure
+    @SuppressWarnings("deprecation")
+    @Override
+    public String getAuthToken() throws AuthFailureError {
+        final AccountManager accountManager = AccountManager.get(mContext);
+        AccountManagerFuture<Bundle> future = accountManager.getAuthToken(mAccount,
+                mAuthTokenType, mNotifyAuthFailure, null, null);
+        Bundle result;
+        try {
+            result = future.getResult();
+        } catch (Exception e) {
+            throw new AuthFailureError("Error while retrieving auth token", e);
+        }
+        String authToken = null;
+        if (future.isDone() && !future.isCancelled()) {
+            if (result.containsKey(AccountManager.KEY_INTENT)) {
+                Intent intent = result.getParcelable(AccountManager.KEY_INTENT);
+                throw new AuthFailureError(intent);
+            }
+            authToken = result.getString(AccountManager.KEY_AUTHTOKEN);
+        }
+        if (authToken == null) {
+            throw new AuthFailureError("Got null auth token for type: " + mAuthTokenType);
+        }
+
+        return authToken;
+    }
+
+    @Override
+    public void invalidateAuthToken(String authToken) {
+        AccountManager.get(mContext).invalidateAuthToken(mAccount.type, authToken);
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/Authenticator.java b/src/main/java/com/android/volley/toolbox/Authenticator.java
new file mode 100644
index 0000000..d9f5e3c
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/Authenticator.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.AuthFailureError;
+
+/**
+ * An interface for interacting with auth tokens.
+ */
+public interface Authenticator {
+    /**
+     * Synchronously retrieves an auth token.
+     *
+     * @throws AuthFailureError If authentication did not succeed
+     */
+    public String getAuthToken() throws AuthFailureError;
+
+    /**
+     * Invalidates the provided auth token.
+     */
+    public void invalidateAuthToken(String authToken);
+}
diff --git a/src/main/java/com/android/volley/toolbox/BasicNetwork.java b/src/main/java/com/android/volley/toolbox/BasicNetwork.java
new file mode 100644
index 0000000..bc1cfdb
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/BasicNetwork.java
@@ -0,0 +1,266 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import android.os.SystemClock;
+
+import com.android.volley.AuthFailureError;
+import com.android.volley.Cache;
+import com.android.volley.Cache.Entry;
+import com.android.volley.Network;
+import com.android.volley.NetworkError;
+import com.android.volley.NetworkResponse;
+import com.android.volley.NoConnectionError;
+import com.android.volley.Request;
+import com.android.volley.RetryPolicy;
+import com.android.volley.ServerError;
+import com.android.volley.TimeoutError;
+import com.android.volley.VolleyError;
+import com.android.volley.VolleyLog;
+
+import org.apache.http.Header;
+import org.apache.http.HttpEntity;
+import org.apache.http.HttpResponse;
+import org.apache.http.HttpStatus;
+import org.apache.http.StatusLine;
+import org.apache.http.conn.ConnectTimeoutException;
+import org.apache.http.impl.cookie.DateUtils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.SocketTimeoutException;
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * A network performing Volley requests over an {@link HttpStack}.
+ */
+public class BasicNetwork implements Network {
+    protected static final boolean DEBUG = VolleyLog.DEBUG;
+
+    private static int SLOW_REQUEST_THRESHOLD_MS = 3000;
+
+    private static int DEFAULT_POOL_SIZE = 4096;
+
+    protected final HttpStack mHttpStack;
+
+    protected final ByteArrayPool mPool;
+
+    /**
+     * @param httpStack HTTP stack to be used
+     */
+    public BasicNetwork(HttpStack httpStack) {
+        // If a pool isn't passed in, then build a small default pool that will give us a lot of
+        // benefit and not use too much memory.
+        this(httpStack, new ByteArrayPool(DEFAULT_POOL_SIZE));
+    }
+
+    /**
+     * @param httpStack HTTP stack to be used
+     * @param pool a buffer pool that improves GC performance in copy operations
+     */
+    public BasicNetwork(HttpStack httpStack, ByteArrayPool pool) {
+        mHttpStack = httpStack;
+        mPool = pool;
+    }
+
+    @Override
+    public NetworkResponse performRequest(Request<?> request) throws VolleyError {
+        long requestStart = SystemClock.elapsedRealtime();
+        while (true) {
+            HttpResponse httpResponse = null;
+            byte[] responseContents = null;
+            Map<String, String> responseHeaders = Collections.emptyMap();
+            try {
+                // Gather headers.
+                Map<String, String> headers = new HashMap<String, String>();
+                addCacheHeaders(headers, request.getCacheEntry());
+                httpResponse = mHttpStack.performRequest(request, headers);
+                StatusLine statusLine = httpResponse.getStatusLine();
+                int statusCode = statusLine.getStatusCode();
+
+                responseHeaders = convertHeaders(httpResponse.getAllHeaders());
+                // Handle cache validation.
+                if (statusCode == HttpStatus.SC_NOT_MODIFIED) {
+
+                    Entry entry = request.getCacheEntry();
+                    if (entry == null) {
+                        return new NetworkResponse(HttpStatus.SC_NOT_MODIFIED, null,
+                                responseHeaders, true,
+                                SystemClock.elapsedRealtime() - requestStart);
+                    }
+
+                    // A HTTP 304 response does not have all header fields. We
+                    // have to use the header fields from the cache entry plus
+                    // the new ones from the response.
+                    // http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5
+                    entry.responseHeaders.putAll(responseHeaders);
+                    return new NetworkResponse(HttpStatus.SC_NOT_MODIFIED, entry.data,
+                            entry.responseHeaders, true,
+                            SystemClock.elapsedRealtime() - requestStart);
+                }
+
+                // Some responses such as 204s do not have content.  We must check.
+                if (httpResponse.getEntity() != null) {
+                  responseContents = entityToBytes(httpResponse.getEntity());
+                } else {
+                  // Add 0 byte response as a way of honestly representing a
+                  // no-content request.
+                  responseContents = new byte[0];
+                }
+
+                // if the request is slow, log it.
+                long requestLifetime = SystemClock.elapsedRealtime() - requestStart;
+                logSlowRequests(requestLifetime, request, responseContents, statusLine);
+
+                if (statusCode < 200 || statusCode > 299) {
+                    throw new IOException();
+                }
+                return new NetworkResponse(statusCode, responseContents, responseHeaders, false,
+                        SystemClock.elapsedRealtime() - requestStart);
+            } catch (SocketTimeoutException e) {
+                attemptRetryOnException("socket", request, new TimeoutError());
+            } catch (ConnectTimeoutException e) {
+                attemptRetryOnException("connection", request, new TimeoutError());
+            } catch (MalformedURLException e) {
+                throw new RuntimeException("Bad URL " + request.getUrl(), e);
+            } catch (IOException e) {
+                int statusCode = 0;
+                NetworkResponse networkResponse = null;
+                if (httpResponse != null) {
+                    statusCode = httpResponse.getStatusLine().getStatusCode();
+                } else {
+                    throw new NoConnectionError(e);
+                }
+                VolleyLog.e("Unexpected response code %d for %s", statusCode, request.getUrl());
+                if (responseContents != null) {
+                    networkResponse = new NetworkResponse(statusCode, responseContents,
+                            responseHeaders, false, SystemClock.elapsedRealtime() - requestStart);
+                    if (statusCode == HttpStatus.SC_UNAUTHORIZED ||
+                            statusCode == HttpStatus.SC_FORBIDDEN) {
+                        attemptRetryOnException("auth",
+                                request, new AuthFailureError(networkResponse));
+                    } else {
+                        // TODO: Only throw ServerError for 5xx status codes.
+                        throw new ServerError(networkResponse);
+                    }
+                } else {
+                    throw new NetworkError(networkResponse);
+                }
+            }
+        }
+    }
+
+    /**
+     * Logs requests that took over SLOW_REQUEST_THRESHOLD_MS to complete.
+     */
+    private void logSlowRequests(long requestLifetime, Request<?> request,
+            byte[] responseContents, StatusLine statusLine) {
+        if (DEBUG || requestLifetime > SLOW_REQUEST_THRESHOLD_MS) {
+            VolleyLog.d("HTTP response for request=<%s> [lifetime=%d], [size=%s], " +
+                    "[rc=%d], [retryCount=%s]", request, requestLifetime,
+                    responseContents != null ? responseContents.length : "null",
+                    statusLine.getStatusCode(), request.getRetryPolicy().getCurrentRetryCount());
+        }
+    }
+
+    /**
+     * Attempts to prepare the request for a retry. If there are no more attempts remaining in the
+     * request's retry policy, a timeout exception is thrown.
+     * @param request The request to use.
+     */
+    private static void attemptRetryOnException(String logPrefix, Request<?> request,
+            VolleyError exception) throws VolleyError {
+        RetryPolicy retryPolicy = request.getRetryPolicy();
+        int oldTimeout = request.getTimeoutMs();
+
+        try {
+            retryPolicy.retry(exception);
+        } catch (VolleyError e) {
+            request.addMarker(
+                    String.format("%s-timeout-giveup [timeout=%s]", logPrefix, oldTimeout));
+            throw e;
+        }
+        request.addMarker(String.format("%s-retry [timeout=%s]", logPrefix, oldTimeout));
+    }
+
+    private void addCacheHeaders(Map<String, String> headers, Cache.Entry entry) {
+        // If there's no cache entry, we're done.
+        if (entry == null) {
+            return;
+        }
+
+        if (entry.etag != null) {
+            headers.put("If-None-Match", entry.etag);
+        }
+
+        if (entry.serverDate > 0) {
+            Date refTime = new Date(entry.serverDate);
+            headers.put("If-Modified-Since", DateUtils.formatDate(refTime));
+        }
+    }
+
+    protected void logError(String what, String url, long start) {
+        long now = SystemClock.elapsedRealtime();
+        VolleyLog.v("HTTP ERROR(%s) %d ms to fetch %s", what, (now - start), url);
+    }
+
+    /** Reads the contents of HttpEntity into a byte[]. */
+    private byte[] entityToBytes(HttpEntity entity) throws IOException, ServerError {
+        PoolingByteArrayOutputStream bytes =
+                new PoolingByteArrayOutputStream(mPool, (int) entity.getContentLength());
+        byte[] buffer = null;
+        try {
+            InputStream in = entity.getContent();
+            if (in == null) {
+                throw new ServerError();
+            }
+            buffer = mPool.getBuf(1024);
+            int count;
+            while ((count = in.read(buffer)) != -1) {
+                bytes.write(buffer, 0, count);
+            }
+            return bytes.toByteArray();
+        } finally {
+            try {
+                // Close the InputStream and release the resources by "consuming the content".
+                entity.consumeContent();
+            } catch (IOException e) {
+                // This can happen if there was an exception above that left the entity in
+                // an invalid state.
+                VolleyLog.v("Error occured when calling consumingContent");
+            }
+            mPool.returnBuf(buffer);
+            bytes.close();
+        }
+    }
+
+    /**
+     * Converts Headers[] to Map<String, String>.
+     */
+    protected static Map<String, String> convertHeaders(Header[] headers) {
+        Map<String, String> result = new TreeMap<String, String>(String.CASE_INSENSITIVE_ORDER);
+        for (int i = 0; i < headers.length; i++) {
+            result.put(headers[i].getName(), headers[i].getValue());
+        }
+        return result;
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/ByteArrayPool.java b/src/main/java/com/android/volley/toolbox/ByteArrayPool.java
new file mode 100644
index 0000000..af95076
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/ByteArrayPool.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * ByteArrayPool is a source and repository of <code>byte[]</code> objects. Its purpose is to
+ * supply those buffers to consumers who need to use them for a short period of time and then
+ * dispose of them. Simply creating and disposing such buffers in the conventional manner can
+ * considerable heap churn and garbage collection delays on Android, which lacks good management of
+ * short-lived heap objects. It may be advantageous to trade off some memory in the form of a
+ * permanently allocated pool of buffers in order to gain heap performance improvements; that is
+ * what this class does.
+ * <p>
+ * A good candidate user for this class is something like an I/O system that uses large temporary
+ * <code>byte[]</code> buffers to copy data around. In these use cases, often the consumer wants
+ * the buffer to be a certain minimum size to ensure good performance (e.g. when copying data chunks
+ * off of a stream), but doesn't mind if the buffer is larger than the minimum. Taking this into
+ * account and also to maximize the odds of being able to reuse a recycled buffer, this class is
+ * free to return buffers larger than the requested size. The caller needs to be able to gracefully
+ * deal with getting buffers any size over the minimum.
+ * <p>
+ * If there is not a suitably-sized buffer in its recycling pool when a buffer is requested, this
+ * class will allocate a new buffer and return it.
+ * <p>
+ * This class has no special ownership of buffers it creates; the caller is free to take a buffer
+ * it receives from this pool, use it permanently, and never return it to the pool; additionally,
+ * it is not harmful to return to this pool a buffer that was allocated elsewhere, provided there
+ * are no other lingering references to it.
+ * <p>
+ * This class ensures that the total size of the buffers in its recycling pool never exceeds a
+ * certain byte limit. When a buffer is returned that would cause the pool to exceed the limit,
+ * least-recently-used buffers are disposed.
+ */
+public class ByteArrayPool {
+    /** The buffer pool, arranged both by last use and by buffer size */
+    private List<byte[]> mBuffersByLastUse = new LinkedList<byte[]>();
+    private List<byte[]> mBuffersBySize = new ArrayList<byte[]>(64);
+
+    /** The total size of the buffers in the pool */
+    private int mCurrentSize = 0;
+
+    /**
+     * The maximum aggregate size of the buffers in the pool. Old buffers are discarded to stay
+     * under this limit.
+     */
+    private final int mSizeLimit;
+
+    /** Compares buffers by size */
+    protected static final Comparator<byte[]> BUF_COMPARATOR = new Comparator<byte[]>() {
+        @Override
+        public int compare(byte[] lhs, byte[] rhs) {
+            return lhs.length - rhs.length;
+        }
+    };
+
+    /**
+     * @param sizeLimit the maximum size of the pool, in bytes
+     */
+    public ByteArrayPool(int sizeLimit) {
+        mSizeLimit = sizeLimit;
+    }
+
+    /**
+     * Returns a buffer from the pool if one is available in the requested size, or allocates a new
+     * one if a pooled one is not available.
+     *
+     * @param len the minimum size, in bytes, of the requested buffer. The returned buffer may be
+     *        larger.
+     * @return a byte[] buffer is always returned.
+     */
+    public synchronized byte[] getBuf(int len) {
+        for (int i = 0; i < mBuffersBySize.size(); i++) {
+            byte[] buf = mBuffersBySize.get(i);
+            if (buf.length >= len) {
+                mCurrentSize -= buf.length;
+                mBuffersBySize.remove(i);
+                mBuffersByLastUse.remove(buf);
+                return buf;
+            }
+        }
+        return new byte[len];
+    }
+
+    /**
+     * Returns a buffer to the pool, throwing away old buffers if the pool would exceed its allotted
+     * size.
+     *
+     * @param buf the buffer to return to the pool.
+     */
+    public synchronized void returnBuf(byte[] buf) {
+        if (buf == null || buf.length > mSizeLimit) {
+            return;
+        }
+        mBuffersByLastUse.add(buf);
+        int pos = Collections.binarySearch(mBuffersBySize, buf, BUF_COMPARATOR);
+        if (pos < 0) {
+            pos = -pos - 1;
+        }
+        mBuffersBySize.add(pos, buf);
+        mCurrentSize += buf.length;
+        trim();
+    }
+
+    /**
+     * Removes buffers from the pool until it is under its size limit.
+     */
+    private synchronized void trim() {
+        while (mCurrentSize > mSizeLimit) {
+            byte[] buf = mBuffersByLastUse.remove(0);
+            mBuffersBySize.remove(buf);
+            mCurrentSize -= buf.length;
+        }
+    }
+
+}
diff --git a/src/main/java/com/android/volley/toolbox/ClearCacheRequest.java b/src/main/java/com/android/volley/toolbox/ClearCacheRequest.java
new file mode 100644
index 0000000..a3478bf
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/ClearCacheRequest.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.Cache;
+import com.android.volley.NetworkResponse;
+import com.android.volley.Request;
+import com.android.volley.Response;
+
+import android.os.Handler;
+import android.os.Looper;
+
+/**
+ * A synthetic request used for clearing the cache.
+ */
+public class ClearCacheRequest extends Request<Object> {
+    private final Cache mCache;
+    private final Runnable mCallback;
+
+    /**
+     * Creates a synthetic request for clearing the cache.
+     * @param cache Cache to clear
+     * @param callback Callback to make on the main thread once the cache is clear,
+     * or null for none
+     */
+    public ClearCacheRequest(Cache cache, Runnable callback) {
+        super(Method.GET, null, null);
+        mCache = cache;
+        mCallback = callback;
+    }
+
+    @Override
+    public boolean isCanceled() {
+        // This is a little bit of a hack, but hey, why not.
+        mCache.clear();
+        if (mCallback != null) {
+            Handler handler = new Handler(Looper.getMainLooper());
+            handler.postAtFrontOfQueue(mCallback);
+        }
+        return true;
+    }
+
+    @Override
+    public Priority getPriority() {
+        return Priority.IMMEDIATE;
+    }
+
+    @Override
+    protected Response<Object> parseNetworkResponse(NetworkResponse response) {
+        return null;
+    }
+
+    @Override
+    protected void deliverResponse(Object response) {
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/DiskBasedCache.java b/src/main/java/com/android/volley/toolbox/DiskBasedCache.java
new file mode 100644
index 0000000..b283788
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/DiskBasedCache.java
@@ -0,0 +1,562 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import android.os.SystemClock;
+
+import com.android.volley.Cache;
+import com.android.volley.VolleyLog;
+
+import java.io.BufferedInputStream;
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Cache implementation that caches files directly onto the hard disk in the specified
+ * directory. The default disk usage size is 5MB, but is configurable.
+ */
+public class DiskBasedCache implements Cache {
+
+    /** Map of the Key, CacheHeader pairs */
+    private final Map<String, CacheHeader> mEntries =
+            new LinkedHashMap<String, CacheHeader>(16, .75f, true);
+
+    /** Total amount of space currently used by the cache in bytes. */
+    private long mTotalSize = 0;
+
+    /** The root directory to use for the cache. */
+    private final File mRootDirectory;
+
+    /** The maximum size of the cache in bytes. */
+    private final int mMaxCacheSizeInBytes;
+
+    /** Default maximum disk usage in bytes. */
+    private static final int DEFAULT_DISK_USAGE_BYTES = 5 * 1024 * 1024;
+
+    /** High water mark percentage for the cache */
+    private static final float HYSTERESIS_FACTOR = 0.9f;
+
+    /** Magic number for current version of cache file format. */
+    private static final int CACHE_MAGIC = 0x20140623;
+
+    /**
+     * Constructs an instance of the DiskBasedCache at the specified directory.
+     * @param rootDirectory The root directory of the cache.
+     * @param maxCacheSizeInBytes The maximum size of the cache in bytes.
+     */
+    public DiskBasedCache(File rootDirectory, int maxCacheSizeInBytes) {
+        mRootDirectory = rootDirectory;
+        mMaxCacheSizeInBytes = maxCacheSizeInBytes;
+    }
+
+    /**
+     * Constructs an instance of the DiskBasedCache at the specified directory using
+     * the default maximum cache size of 5MB.
+     * @param rootDirectory The root directory of the cache.
+     */
+    public DiskBasedCache(File rootDirectory) {
+        this(rootDirectory, DEFAULT_DISK_USAGE_BYTES);
+    }
+
+    /**
+     * Clears the cache. Deletes all cached files from disk.
+     */
+    @Override
+    public synchronized void clear() {
+        File[] files = mRootDirectory.listFiles();
+        if (files != null) {
+            for (File file : files) {
+                file.delete();
+            }
+        }
+        mEntries.clear();
+        mTotalSize = 0;
+        VolleyLog.d("Cache cleared.");
+    }
+
+    /**
+     * Returns the cache entry with the specified key if it exists, null otherwise.
+     */
+    @Override
+    public synchronized Entry get(String key) {
+        CacheHeader entry = mEntries.get(key);
+        // if the entry does not exist, return.
+        if (entry == null) {
+            return null;
+        }
+
+        File file = getFileForKey(key);
+        CountingInputStream cis = null;
+        try {
+            cis = new CountingInputStream(new FileInputStream(file));
+            CacheHeader.readHeader(cis); // eat header
+            byte[] data = streamToBytes(cis, (int) (file.length() - cis.bytesRead));
+            return entry.toCacheEntry(data);
+        } catch (IOException e) {
+            VolleyLog.d("%s: %s", file.getAbsolutePath(), e.toString());
+            remove(key);
+            return null;
+        } finally {
+            if (cis != null) {
+                try {
+                    cis.close();
+                } catch (IOException ioe) {
+                    return null;
+                }
+            }
+        }
+    }
+
+    /**
+     * Initializes the DiskBasedCache by scanning for all files currently in the
+     * specified root directory. Creates the root directory if necessary.
+     */
+    @Override
+    public synchronized void initialize() {
+        if (!mRootDirectory.exists()) {
+            if (!mRootDirectory.mkdirs()) {
+                VolleyLog.e("Unable to create cache dir %s", mRootDirectory.getAbsolutePath());
+            }
+            return;
+        }
+
+        File[] files = mRootDirectory.listFiles();
+        if (files == null) {
+            return;
+        }
+        for (File file : files) {
+            BufferedInputStream fis = null;
+            try {
+                fis = new BufferedInputStream(new FileInputStream(file));
+                CacheHeader entry = CacheHeader.readHeader(fis);
+                entry.size = file.length();
+                putEntry(entry.key, entry);
+            } catch (IOException e) {
+                if (file != null) {
+                   file.delete();
+                }
+            } finally {
+                try {
+                    if (fis != null) {
+                        fis.close();
+                    }
+                } catch (IOException ignored) { }
+            }
+        }
+    }
+
+    /**
+     * Invalidates an entry in the cache.
+     * @param key Cache key
+     * @param fullExpire True to fully expire the entry, false to soft expire
+     */
+    @Override
+    public synchronized void invalidate(String key, boolean fullExpire) {
+        Entry entry = get(key);
+        if (entry != null) {
+            entry.softTtl = 0;
+            if (fullExpire) {
+                entry.ttl = 0;
+            }
+            put(key, entry);
+        }
+
+    }
+
+    /**
+     * Puts the entry with the specified key into the cache.
+     */
+    @Override
+    public synchronized void put(String key, Entry entry) {
+        pruneIfNeeded(entry.data.length);
+        File file = getFileForKey(key);
+        try {
+            FileOutputStream fos = new FileOutputStream(file);
+            CacheHeader e = new CacheHeader(key, entry);
+            boolean success = e.writeHeader(fos);
+            if (!success) {
+                fos.close();
+                VolleyLog.d("Failed to write header for %s", file.getAbsolutePath());
+                throw new IOException();
+            }
+            fos.write(entry.data);
+            fos.close();
+            putEntry(key, e);
+            return;
+        } catch (IOException e) {
+        }
+        boolean deleted = file.delete();
+        if (!deleted) {
+            VolleyLog.d("Could not clean up file %s", file.getAbsolutePath());
+        }
+    }
+
+    /**
+     * Removes the specified key from the cache if it exists.
+     */
+    @Override
+    public synchronized void remove(String key) {
+        boolean deleted = getFileForKey(key).delete();
+        removeEntry(key);
+        if (!deleted) {
+            VolleyLog.d("Could not delete cache entry for key=%s, filename=%s",
+                    key, getFilenameForKey(key));
+        }
+    }
+
+    /**
+     * Creates a pseudo-unique filename for the specified cache key.
+     * @param key The key to generate a file name for.
+     * @return A pseudo-unique filename.
+     */
+    private String getFilenameForKey(String key) {
+        int firstHalfLength = key.length() / 2;
+        String localFilename = String.valueOf(key.substring(0, firstHalfLength).hashCode());
+        localFilename += String.valueOf(key.substring(firstHalfLength).hashCode());
+        return localFilename;
+    }
+
+    /**
+     * Returns a file object for the given cache key.
+     */
+    public File getFileForKey(String key) {
+        return new File(mRootDirectory, getFilenameForKey(key));
+    }
+
+    /**
+     * Prunes the cache to fit the amount of bytes specified.
+     * @param neededSpace The amount of bytes we are trying to fit into the cache.
+     */
+    private void pruneIfNeeded(int neededSpace) {
+        if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes) {
+            return;
+        }
+        if (VolleyLog.DEBUG) {
+            VolleyLog.v("Pruning old cache entries.");
+        }
+
+        long before = mTotalSize;
+        int prunedFiles = 0;
+        long startTime = SystemClock.elapsedRealtime();
+
+        Iterator<Map.Entry<String, CacheHeader>> iterator = mEntries.entrySet().iterator();
+        while (iterator.hasNext()) {
+            Map.Entry<String, CacheHeader> entry = iterator.next();
+            CacheHeader e = entry.getValue();
+            boolean deleted = getFileForKey(e.key).delete();
+            if (deleted) {
+                mTotalSize -= e.size;
+            } else {
+               VolleyLog.d("Could not delete cache entry for key=%s, filename=%s",
+                       e.key, getFilenameForKey(e.key));
+            }
+            iterator.remove();
+            prunedFiles++;
+
+            if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes * HYSTERESIS_FACTOR) {
+                break;
+            }
+        }
+
+        if (VolleyLog.DEBUG) {
+            VolleyLog.v("pruned %d files, %d bytes, %d ms",
+                    prunedFiles, (mTotalSize - before), SystemClock.elapsedRealtime() - startTime);
+        }
+    }
+
+    /**
+     * Puts the entry with the specified key into the cache.
+     * @param key The key to identify the entry by.
+     * @param entry The entry to cache.
+     */
+    private void putEntry(String key, CacheHeader entry) {
+        if (!mEntries.containsKey(key)) {
+            mTotalSize += entry.size;
+        } else {
+            CacheHeader oldEntry = mEntries.get(key);
+            mTotalSize += (entry.size - oldEntry.size);
+        }
+        mEntries.put(key, entry);
+    }
+
+    /**
+     * Removes the entry identified by 'key' from the cache.
+     */
+    private void removeEntry(String key) {
+        CacheHeader entry = mEntries.get(key);
+        if (entry != null) {
+            mTotalSize -= entry.size;
+            mEntries.remove(key);
+        }
+    }
+
+    /**
+     * Reads the contents of an InputStream into a byte[].
+     * */
+    private static byte[] streamToBytes(InputStream in, int length) throws IOException {
+        byte[] bytes = new byte[length];
+        int count;
+        int pos = 0;
+        while (pos < length && ((count = in.read(bytes, pos, length - pos)) != -1)) {
+            pos += count;
+        }
+        if (pos != length) {
+            throw new IOException("Expected " + length + " bytes, read " + pos + " bytes");
+        }
+        return bytes;
+    }
+
+    /**
+     * Handles holding onto the cache headers for an entry.
+     */
+    // Visible for testing.
+    static class CacheHeader {
+        /** The size of the data identified by this CacheHeader. (This is not
+         * serialized to disk. */
+        public long size;
+
+        /** The key that identifies the cache entry. */
+        public String key;
+
+        /** ETag for cache coherence. */
+        public String etag;
+
+        /** Date of this response as reported by the server. */
+        public long serverDate;
+
+        /** TTL for this record. */
+        public long ttl;
+
+        /** Soft TTL for this record. */
+        public long softTtl;
+
+        /** Headers from the response resulting in this cache entry. */
+        public Map<String, String> responseHeaders;
+
+        private CacheHeader() { }
+
+        /**
+         * Instantiates a new CacheHeader object
+         * @param key The key that identifies the cache entry
+         * @param entry The cache entry.
+         */
+        public CacheHeader(String key, Entry entry) {
+            this.key = key;
+            this.size = entry.data.length;
+            this.etag = entry.etag;
+            this.serverDate = entry.serverDate;
+            this.ttl = entry.ttl;
+            this.softTtl = entry.softTtl;
+            this.responseHeaders = entry.responseHeaders;
+        }
+
+        /**
+         * Reads the header off of an InputStream and returns a CacheHeader object.
+         * @param is The InputStream to read from.
+         * @throws IOException
+         */
+        public static CacheHeader readHeader(InputStream is) throws IOException {
+            CacheHeader entry = new CacheHeader();
+            int magic = readInt(is);
+            if (magic != CACHE_MAGIC) {
+                // don't bother deleting, it'll get pruned eventually
+                throw new IOException();
+            }
+            entry.key = readString(is);
+            entry.etag = readString(is);
+            if (entry.etag.equals("")) {
+                entry.etag = null;
+            }
+            entry.serverDate = readLong(is);
+            entry.ttl = readLong(is);
+            entry.softTtl = readLong(is);
+            entry.responseHeaders = readStringStringMap(is);
+            return entry;
+        }
+
+        /**
+         * Creates a cache entry for the specified data.
+         */
+        public Entry toCacheEntry(byte[] data) {
+            Entry e = new Entry();
+            e.data = data;
+            e.etag = etag;
+            e.serverDate = serverDate;
+            e.ttl = ttl;
+            e.softTtl = softTtl;
+            e.responseHeaders = responseHeaders;
+            return e;
+        }
+
+
+        /**
+         * Writes the contents of this CacheHeader to the specified OutputStream.
+         */
+        public boolean writeHeader(OutputStream os) {
+            try {
+                writeInt(os, CACHE_MAGIC);
+                writeString(os, key);
+                writeString(os, etag == null ? "" : etag);
+                writeLong(os, serverDate);
+                writeLong(os, ttl);
+                writeLong(os, softTtl);
+                writeStringStringMap(responseHeaders, os);
+                os.flush();
+                return true;
+            } catch (IOException e) {
+                VolleyLog.d("%s", e.toString());
+                return false;
+            }
+        }
+
+    }
+
+    private static class CountingInputStream extends FilterInputStream {
+        private int bytesRead = 0;
+
+        private CountingInputStream(InputStream in) {
+            super(in);
+        }
+
+        @Override
+        public int read() throws IOException {
+            int result = super.read();
+            if (result != -1) {
+                bytesRead++;
+            }
+            return result;
+        }
+
+        @Override
+        public int read(byte[] buffer, int offset, int count) throws IOException {
+            int result = super.read(buffer, offset, count);
+            if (result != -1) {
+                bytesRead += result;
+            }
+            return result;
+        }
+    }
+
+    /*
+     * Homebrewed simple serialization system used for reading and writing cache
+     * headers on disk. Once upon a time, this used the standard Java
+     * Object{Input,Output}Stream, but the default implementation relies heavily
+     * on reflection (even for standard types) and generates a ton of garbage.
+     */
+
+    /**
+     * Simple wrapper around {@link InputStream#read()} that throws EOFException
+     * instead of returning -1.
+     */
+    private static int read(InputStream is) throws IOException {
+        int b = is.read();
+        if (b == -1) {
+            throw new EOFException();
+        }
+        return b;
+    }
+
+    static void writeInt(OutputStream os, int n) throws IOException {
+        os.write((n >> 0) & 0xff);
+        os.write((n >> 8) & 0xff);
+        os.write((n >> 16) & 0xff);
+        os.write((n >> 24) & 0xff);
+    }
+
+    static int readInt(InputStream is) throws IOException {
+        int n = 0;
+        n |= (read(is) << 0);
+        n |= (read(is) << 8);
+        n |= (read(is) << 16);
+        n |= (read(is) << 24);
+        return n;
+    }
+
+    static void writeLong(OutputStream os, long n) throws IOException {
+        os.write((byte)(n >>> 0));
+        os.write((byte)(n >>> 8));
+        os.write((byte)(n >>> 16));
+        os.write((byte)(n >>> 24));
+        os.write((byte)(n >>> 32));
+        os.write((byte)(n >>> 40));
+        os.write((byte)(n >>> 48));
+        os.write((byte)(n >>> 56));
+    }
+
+    static long readLong(InputStream is) throws IOException {
+        long n = 0;
+        n |= ((read(is) & 0xFFL) << 0);
+        n |= ((read(is) & 0xFFL) << 8);
+        n |= ((read(is) & 0xFFL) << 16);
+        n |= ((read(is) & 0xFFL) << 24);
+        n |= ((read(is) & 0xFFL) << 32);
+        n |= ((read(is) & 0xFFL) << 40);
+        n |= ((read(is) & 0xFFL) << 48);
+        n |= ((read(is) & 0xFFL) << 56);
+        return n;
+    }
+
+    static void writeString(OutputStream os, String s) throws IOException {
+        byte[] b = s.getBytes("UTF-8");
+        writeLong(os, b.length);
+        os.write(b, 0, b.length);
+    }
+
+    static String readString(InputStream is) throws IOException {
+        int n = (int) readLong(is);
+        byte[] b = streamToBytes(is, n);
+        return new String(b, "UTF-8");
+    }
+
+    static void writeStringStringMap(Map<String, String> map, OutputStream os) throws IOException {
+        if (map != null) {
+            writeInt(os, map.size());
+            for (Map.Entry<String, String> entry : map.entrySet()) {
+                writeString(os, entry.getKey());
+                writeString(os, entry.getValue());
+            }
+        } else {
+            writeInt(os, 0);
+        }
+    }
+
+    static Map<String, String> readStringStringMap(InputStream is) throws IOException {
+        int size = readInt(is);
+        Map<String, String> result = (size == 0)
+                ? Collections.<String, String>emptyMap()
+                : new HashMap<String, String>(size);
+        for (int i = 0; i < size; i++) {
+            String key = readString(is).intern();
+            String value = readString(is).intern();
+            result.put(key, value);
+        }
+        return result;
+    }
+
+
+}
diff --git a/src/main/java/com/android/volley/toolbox/HttpClientStack.java b/src/main/java/com/android/volley/toolbox/HttpClientStack.java
new file mode 100644
index 0000000..377110e
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/HttpClientStack.java
@@ -0,0 +1,194 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.AuthFailureError;
+import com.android.volley.Request;
+import com.android.volley.Request.Method;
+
+import org.apache.http.HttpEntity;
+import org.apache.http.HttpResponse;
+import org.apache.http.NameValuePair;
+import org.apache.http.client.HttpClient;
+import org.apache.http.client.methods.HttpDelete;
+import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.methods.HttpHead;
+import org.apache.http.client.methods.HttpOptions;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.client.methods.HttpPut;
+import org.apache.http.client.methods.HttpTrace;
+import org.apache.http.client.methods.HttpUriRequest;
+import org.apache.http.entity.ByteArrayEntity;
+import org.apache.http.message.BasicNameValuePair;
+import org.apache.http.params.HttpConnectionParams;
+import org.apache.http.params.HttpParams;
+
+import java.io.IOException;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * An HttpStack that performs request over an {@link HttpClient}.
+ */
+public class HttpClientStack implements HttpStack {
+    protected final HttpClient mClient;
+
+    private final static String HEADER_CONTENT_TYPE = "Content-Type";
+
+    public HttpClientStack(HttpClient client) {
+        mClient = client;
+    }
+
+    private static void addHeaders(HttpUriRequest httpRequest, Map<String, String> headers) {
+        for (String key : headers.keySet()) {
+            httpRequest.setHeader(key, headers.get(key));
+        }
+    }
+
+    @SuppressWarnings("unused")
+    private static List<NameValuePair> getPostParameterPairs(Map<String, String> postParams) {
+        List<NameValuePair> result = new ArrayList<NameValuePair>(postParams.size());
+        for (String key : postParams.keySet()) {
+            result.add(new BasicNameValuePair(key, postParams.get(key)));
+        }
+        return result;
+    }
+
+    @Override
+    public HttpResponse performRequest(Request<?> request, Map<String, String> additionalHeaders)
+            throws IOException, AuthFailureError {
+        HttpUriRequest httpRequest = createHttpRequest(request, additionalHeaders);
+        addHeaders(httpRequest, additionalHeaders);
+        addHeaders(httpRequest, request.getHeaders());
+        onPrepareRequest(httpRequest);
+        HttpParams httpParams = httpRequest.getParams();
+        int timeoutMs = request.getTimeoutMs();
+        // TODO: Reevaluate this connection timeout based on more wide-scale
+        // data collection and possibly different for wifi vs. 3G.
+        HttpConnectionParams.setConnectionTimeout(httpParams, 5000);
+        HttpConnectionParams.setSoTimeout(httpParams, timeoutMs);
+        return mClient.execute(httpRequest);
+    }
+
+    /**
+     * Creates the appropriate subclass of HttpUriRequest for passed in request.
+     */
+    @SuppressWarnings("deprecation")
+    /* protected */ static HttpUriRequest createHttpRequest(Request<?> request,
+            Map<String, String> additionalHeaders) throws AuthFailureError {
+        switch (request.getMethod()) {
+            case Method.DEPRECATED_GET_OR_POST: {
+                // This is the deprecated way that needs to be handled for backwards compatibility.
+                // If the request's post body is null, then the assumption is that the request is
+                // GET.  Otherwise, it is assumed that the request is a POST.
+                byte[] postBody = request.getPostBody();
+                if (postBody != null) {
+                    HttpPost postRequest = new HttpPost(request.getUrl());
+                    postRequest.addHeader(HEADER_CONTENT_TYPE, request.getPostBodyContentType());
+                    HttpEntity entity;
+                    entity = new ByteArrayEntity(postBody);
+                    postRequest.setEntity(entity);
+                    return postRequest;
+                } else {
+                    return new HttpGet(request.getUrl());
+                }
+            }
+            case Method.GET:
+                return new HttpGet(request.getUrl());
+            case Method.DELETE:
+                return new HttpDelete(request.getUrl());
+            case Method.POST: {
+                HttpPost postRequest = new HttpPost(request.getUrl());
+                postRequest.addHeader(HEADER_CONTENT_TYPE, request.getBodyContentType());
+                setEntityIfNonEmptyBody(postRequest, request);
+                return postRequest;
+            }
+            case Method.PUT: {
+                HttpPut putRequest = new HttpPut(request.getUrl());
+                putRequest.addHeader(HEADER_CONTENT_TYPE, request.getBodyContentType());
+                setEntityIfNonEmptyBody(putRequest, request);
+                return putRequest;
+            }
+            case Method.HEAD:
+                return new HttpHead(request.getUrl());
+            case Method.OPTIONS:
+                return new HttpOptions(request.getUrl());
+            case Method.TRACE:
+                return new HttpTrace(request.getUrl());
+            case Method.PATCH: {
+                HttpPatch patchRequest = new HttpPatch(request.getUrl());
+                patchRequest.addHeader(HEADER_CONTENT_TYPE, request.getBodyContentType());
+                setEntityIfNonEmptyBody(patchRequest, request);
+                return patchRequest;
+            }
+            default:
+                throw new IllegalStateException("Unknown request method.");
+        }
+    }
+
+    private static void setEntityIfNonEmptyBody(HttpEntityEnclosingRequestBase httpRequest,
+            Request<?> request) throws AuthFailureError {
+        byte[] body = request.getBody();
+        if (body != null) {
+            HttpEntity entity = new ByteArrayEntity(body);
+            httpRequest.setEntity(entity);
+        }
+    }
+
+    /**
+     * Called before the request is executed using the underlying HttpClient.
+     *
+     * <p>Overwrite in subclasses to augment the request.</p>
+     */
+    protected void onPrepareRequest(HttpUriRequest request) throws IOException {
+        // Nothing.
+    }
+
+    /**
+     * The HttpPatch class does not exist in the Android framework, so this has been defined here.
+     */
+    public static final class HttpPatch extends HttpEntityEnclosingRequestBase {
+
+        public final static String METHOD_NAME = "PATCH";
+
+        public HttpPatch() {
+            super();
+        }
+
+        public HttpPatch(final URI uri) {
+            super();
+            setURI(uri);
+        }
+
+        /**
+         * @throws IllegalArgumentException if the uri is invalid.
+         */
+        public HttpPatch(final String uri) {
+            super();
+            setURI(URI.create(uri));
+        }
+
+        @Override
+        public String getMethod() {
+            return METHOD_NAME;
+        }
+
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/HttpHeaderParser.java b/src/main/java/com/android/volley/toolbox/HttpHeaderParser.java
new file mode 100644
index 0000000..cb08432
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/HttpHeaderParser.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.Cache;
+import com.android.volley.NetworkResponse;
+
+import org.apache.http.impl.cookie.DateParseException;
+import org.apache.http.impl.cookie.DateUtils;
+import org.apache.http.protocol.HTTP;
+
+import java.util.Map;
+
+/**
+ * Utility methods for parsing HTTP headers.
+ */
+public class HttpHeaderParser {
+
+    /**
+     * Extracts a {@link Cache.Entry} from a {@link NetworkResponse}.
+     *
+     * @param response The network response to parse headers from
+     * @return a cache entry for the given response, or null if the response is not cacheable.
+     */
+    public static Cache.Entry parseCacheHeaders(NetworkResponse response) {
+        long now = System.currentTimeMillis();
+
+        Map<String, String> headers = response.headers;
+
+        long serverDate = 0;
+        long serverExpires = 0;
+        long softExpire = 0;
+        long maxAge = 0;
+        boolean hasCacheControl = false;
+
+        String serverEtag = null;
+        String headerValue;
+
+        headerValue = headers.get("Date");
+        if (headerValue != null) {
+            serverDate = parseDateAsEpoch(headerValue);
+        }
+
+        headerValue = headers.get("Cache-Control");
+        if (headerValue != null) {
+            hasCacheControl = true;
+            String[] tokens = headerValue.split(",");
+            for (int i = 0; i < tokens.length; i++) {
+                String token = tokens[i].trim();
+                if (token.equals("no-cache") || token.equals("no-store")) {
+                    return null;
+                } else if (token.startsWith("max-age=")) {
+                    try {
+                        maxAge = Long.parseLong(token.substring(8));
+                    } catch (Exception e) {
+                    }
+                } else if (token.equals("must-revalidate") || token.equals("proxy-revalidate")) {
+                    maxAge = 0;
+                }
+            }
+        }
+
+        headerValue = headers.get("Expires");
+        if (headerValue != null) {
+            serverExpires = parseDateAsEpoch(headerValue);
+        }
+
+        serverEtag = headers.get("ETag");
+
+        // Cache-Control takes precedence over an Expires header, even if both exist and Expires
+        // is more restrictive.
+        if (hasCacheControl) {
+            softExpire = now + maxAge * 1000;
+        } else if (serverDate > 0 && serverExpires >= serverDate) {
+            // Default semantic for Expire header in HTTP specification is softExpire.
+            softExpire = now + (serverExpires - serverDate);
+        }
+
+        Cache.Entry entry = new Cache.Entry();
+        entry.data = response.data;
+        entry.etag = serverEtag;
+        entry.softTtl = softExpire;
+        entry.ttl = entry.softTtl;
+        entry.serverDate = serverDate;
+        entry.responseHeaders = headers;
+
+        return entry;
+    }
+
+    /**
+     * Parse date in RFC1123 format, and return its value as epoch
+     */
+    public static long parseDateAsEpoch(String dateStr) {
+        try {
+            // Parse date in RFC1123 format if this header contains one
+            return DateUtils.parseDate(dateStr).getTime();
+        } catch (DateParseException e) {
+            // Date in invalid format, fallback to 0
+            return 0;
+        }
+    }
+
+    /**
+     * Returns the charset specified in the Content-Type of this header,
+     * or the HTTP default (ISO-8859-1) if none can be found.
+     */
+    public static String parseCharset(Map<String, String> headers) {
+        String contentType = headers.get(HTTP.CONTENT_TYPE);
+        if (contentType != null) {
+            String[] params = contentType.split(";");
+            for (int i = 1; i < params.length; i++) {
+                String[] pair = params[i].trim().split("=");
+                if (pair.length == 2) {
+                    if (pair[0].equals("charset")) {
+                        return pair[1];
+                    }
+                }
+            }
+        }
+
+        return HTTP.DEFAULT_CONTENT_CHARSET;
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/HttpStack.java b/src/main/java/com/android/volley/toolbox/HttpStack.java
new file mode 100644
index 0000000..a52fd06
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/HttpStack.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.AuthFailureError;
+import com.android.volley.Request;
+
+import org.apache.http.HttpResponse;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * An HTTP stack abstraction.
+ */
+public interface HttpStack {
+    /**
+     * Performs an HTTP request with the given parameters.
+     *
+     * <p>A GET request is sent if request.getPostBody() == null. A POST request is sent otherwise,
+     * and the Content-Type header is set to request.getPostBodyContentType().</p>
+     *
+     * @param request the request to perform
+     * @param additionalHeaders additional headers to be sent together with
+     *         {@link Request#getHeaders()}
+     * @return the HTTP response
+     */
+    public HttpResponse performRequest(Request<?> request, Map<String, String> additionalHeaders)
+        throws IOException, AuthFailureError;
+
+}
diff --git a/src/main/java/com/android/volley/toolbox/HurlStack.java b/src/main/java/com/android/volley/toolbox/HurlStack.java
new file mode 100644
index 0000000..31d57f0
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/HurlStack.java
@@ -0,0 +1,245 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.AuthFailureError;
+import com.android.volley.Request;
+import com.android.volley.Request.Method;
+
+import org.apache.http.Header;
+import org.apache.http.HttpEntity;
+import org.apache.http.HttpResponse;
+import org.apache.http.ProtocolVersion;
+import org.apache.http.StatusLine;
+import org.apache.http.entity.BasicHttpEntity;
+import org.apache.http.message.BasicHeader;
+import org.apache.http.message.BasicHttpResponse;
+import org.apache.http.message.BasicStatusLine;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import javax.net.ssl.HttpsURLConnection;
+import javax.net.ssl.SSLSocketFactory;
+
+/**
+ * An {@link HttpStack} based on {@link HttpURLConnection}.
+ */
+public class HurlStack implements HttpStack {
+
+    private static final String HEADER_CONTENT_TYPE = "Content-Type";
+
+    /**
+     * An interface for transforming URLs before use.
+     */
+    public interface UrlRewriter {
+        /**
+         * Returns a URL to use instead of the provided one, or null to indicate
+         * this URL should not be used at all.
+         */
+        public String rewriteUrl(String originalUrl);
+    }
+
+    private final UrlRewriter mUrlRewriter;
+    private final SSLSocketFactory mSslSocketFactory;
+
+    public HurlStack() {
+        this(null);
+    }
+
+    /**
+     * @param urlRewriter Rewriter to use for request URLs
+     */
+    public HurlStack(UrlRewriter urlRewriter) {
+        this(urlRewriter, null);
+    }
+
+    /**
+     * @param urlRewriter Rewriter to use for request URLs
+     * @param sslSocketFactory SSL factory to use for HTTPS connections
+     */
+    public HurlStack(UrlRewriter urlRewriter, SSLSocketFactory sslSocketFactory) {
+        mUrlRewriter = urlRewriter;
+        mSslSocketFactory = sslSocketFactory;
+    }
+
+    @Override
+    public HttpResponse performRequest(Request<?> request, Map<String, String> additionalHeaders)
+            throws IOException, AuthFailureError {
+        String url = request.getUrl();
+        HashMap<String, String> map = new HashMap<String, String>();
+        map.putAll(request.getHeaders());
+        map.putAll(additionalHeaders);
+        if (mUrlRewriter != null) {
+            String rewritten = mUrlRewriter.rewriteUrl(url);
+            if (rewritten == null) {
+                throw new IOException("URL blocked by rewriter: " + url);
+            }
+            url = rewritten;
+        }
+        URL parsedUrl = new URL(url);
+        HttpURLConnection connection = openConnection(parsedUrl, request);
+        for (String headerName : map.keySet()) {
+            connection.addRequestProperty(headerName, map.get(headerName));
+        }
+        setConnectionParametersForRequest(connection, request);
+        // Initialize HttpResponse with data from the HttpURLConnection.
+        ProtocolVersion protocolVersion = new ProtocolVersion("HTTP", 1, 1);
+        int responseCode = connection.getResponseCode();
+        if (responseCode == -1) {
+            // -1 is returned by getResponseCode() if the response code could not be retrieved.
+            // Signal to the caller that something was wrong with the connection.
+            throw new IOException("Could not retrieve response code from HttpUrlConnection.");
+        }
+        StatusLine responseStatus = new BasicStatusLine(protocolVersion,
+                connection.getResponseCode(), connection.getResponseMessage());
+        BasicHttpResponse response = new BasicHttpResponse(responseStatus);
+        response.setEntity(entityFromConnection(connection));
+        for (Entry<String, List<String>> header : connection.getHeaderFields().entrySet()) {
+            if (header.getKey() != null) {
+                Header h = new BasicHeader(header.getKey(), header.getValue().get(0));
+                response.addHeader(h);
+            }
+        }
+        return response;
+    }
+
+    /**
+     * Initializes an {@link HttpEntity} from the given {@link HttpURLConnection}.
+     * @param connection
+     * @return an HttpEntity populated with data from <code>connection</code>.
+     */
+    private static HttpEntity entityFromConnection(HttpURLConnection connection) {
+        BasicHttpEntity entity = new BasicHttpEntity();
+        InputStream inputStream;
+        try {
+            inputStream = connection.getInputStream();
+        } catch (IOException ioe) {
+            inputStream = connection.getErrorStream();
+        }
+        entity.setContent(inputStream);
+        entity.setContentLength(connection.getContentLength());
+        entity.setContentEncoding(connection.getContentEncoding());
+        entity.setContentType(connection.getContentType());
+        return entity;
+    }
+
+    /**
+     * Create an {@link HttpURLConnection} for the specified {@code url}.
+     */
+    protected HttpURLConnection createConnection(URL url) throws IOException {
+        return (HttpURLConnection) url.openConnection();
+    }
+
+    /**
+     * Opens an {@link HttpURLConnection} with parameters.
+     * @param url
+     * @return an open connection
+     * @throws IOException
+     */
+    private HttpURLConnection openConnection(URL url, Request<?> request) throws IOException {
+        HttpURLConnection connection = createConnection(url);
+
+        int timeoutMs = request.getTimeoutMs();
+        connection.setConnectTimeout(timeoutMs);
+        connection.setReadTimeout(timeoutMs);
+        connection.setUseCaches(false);
+        connection.setDoInput(true);
+
+        // use caller-provided custom SslSocketFactory, if any, for HTTPS
+        if ("https".equals(url.getProtocol()) && mSslSocketFactory != null) {
+            ((HttpsURLConnection)connection).setSSLSocketFactory(mSslSocketFactory);
+        }
+
+        return connection;
+    }
+
+    @SuppressWarnings("deprecation")
+    /* package */ static void setConnectionParametersForRequest(HttpURLConnection connection,
+            Request<?> request) throws IOException, AuthFailureError {
+        switch (request.getMethod()) {
+            case Method.DEPRECATED_GET_OR_POST:
+                // This is the deprecated way that needs to be handled for backwards compatibility.
+                // If the request's post body is null, then the assumption is that the request is
+                // GET.  Otherwise, it is assumed that the request is a POST.
+                byte[] postBody = request.getPostBody();
+                if (postBody != null) {
+                    // Prepare output. There is no need to set Content-Length explicitly,
+                    // since this is handled by HttpURLConnection using the size of the prepared
+                    // output stream.
+                    connection.setDoOutput(true);
+                    connection.setRequestMethod("POST");
+                    connection.addRequestProperty(HEADER_CONTENT_TYPE,
+                            request.getPostBodyContentType());
+                    DataOutputStream out = new DataOutputStream(connection.getOutputStream());
+                    out.write(postBody);
+                    out.close();
+                }
+                break;
+            case Method.GET:
+                // Not necessary to set the request method because connection defaults to GET but
+                // being explicit here.
+                connection.setRequestMethod("GET");
+                break;
+            case Method.DELETE:
+                connection.setRequestMethod("DELETE");
+                break;
+            case Method.POST:
+                connection.setRequestMethod("POST");
+                addBodyIfExists(connection, request);
+                break;
+            case Method.PUT:
+                connection.setRequestMethod("PUT");
+                addBodyIfExists(connection, request);
+                break;
+            case Method.HEAD:
+                connection.setRequestMethod("HEAD");
+                break;
+            case Method.OPTIONS:
+                connection.setRequestMethod("OPTIONS");
+                break;
+            case Method.TRACE:
+                connection.setRequestMethod("TRACE");
+                break;
+            case Method.PATCH:
+                connection.setRequestMethod("PATCH");
+                addBodyIfExists(connection, request);
+                break;
+            default:
+                throw new IllegalStateException("Unknown method type.");
+        }
+    }
+
+    private static void addBodyIfExists(HttpURLConnection connection, Request<?> request)
+            throws IOException, AuthFailureError {
+        byte[] body = request.getBody();
+        if (body != null) {
+            connection.setDoOutput(true);
+            connection.addRequestProperty(HEADER_CONTENT_TYPE, request.getBodyContentType());
+            DataOutputStream out = new DataOutputStream(connection.getOutputStream());
+            out.write(body);
+            out.close();
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/ImageLoader.java b/src/main/java/com/android/volley/toolbox/ImageLoader.java
new file mode 100644
index 0000000..5348dc6
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/ImageLoader.java
@@ -0,0 +1,482 @@
+/**
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.volley.toolbox;
+
+import android.graphics.Bitmap;
+import android.graphics.Bitmap.Config;
+import android.os.Handler;
+import android.os.Looper;
+import android.widget.ImageView;
+
+import com.android.volley.Request;
+import com.android.volley.RequestQueue;
+import com.android.volley.Response.ErrorListener;
+import com.android.volley.Response.Listener;
+import com.android.volley.VolleyError;
+
+import java.util.HashMap;
+import java.util.LinkedList;
+
+/**
+ * Helper that handles loading and caching images from remote URLs.
+ *
+ * The simple way to use this class is to call {@link ImageLoader#get(String, ImageListener)}
+ * and to pass in the default image listener provided by
+ * {@link ImageLoader#getImageListener(ImageView, int, int)}. Note that all function calls to
+ * this class must be made from the main thead, and all responses will be delivered to the main
+ * thread as well.
+ */
+public class ImageLoader {
+    /** RequestQueue for dispatching ImageRequests onto. */
+    private final RequestQueue mRequestQueue;
+
+    /** Amount of time to wait after first response arrives before delivering all responses. */
+    private int mBatchResponseDelayMs = 100;
+
+    /** The cache implementation to be used as an L1 cache before calling into volley. */
+    private final ImageCache mCache;
+
+    /**
+     * HashMap of Cache keys -> BatchedImageRequest used to track in-flight requests so
+     * that we can coalesce multiple requests to the same URL into a single network request.
+     */
+    private final HashMap<String, BatchedImageRequest> mInFlightRequests =
+            new HashMap<String, BatchedImageRequest>();
+
+    /** HashMap of the currently pending responses (waiting to be delivered). */
+    private final HashMap<String, BatchedImageRequest> mBatchedResponses =
+            new HashMap<String, BatchedImageRequest>();
+
+    /** Handler to the main thread. */
+    private final Handler mHandler = new Handler(Looper.getMainLooper());
+
+    /** Runnable for in-flight response delivery. */
+    private Runnable mRunnable;
+
+    /**
+     * Simple cache adapter interface. If provided to the ImageLoader, it
+     * will be used as an L1 cache before dispatch to Volley. Implementations
+     * must not block. Implementation with an LruCache is recommended.
+     */
+    public interface ImageCache {
+        public Bitmap getBitmap(String url);
+        public void putBitmap(String url, Bitmap bitmap);
+    }
+
+    /**
+     * Constructs a new ImageLoader.
+     * @param queue The RequestQueue to use for making image requests.
+     * @param imageCache The cache to use as an L1 cache.
+     */
+    public ImageLoader(RequestQueue queue, ImageCache imageCache) {
+        mRequestQueue = queue;
+        mCache = imageCache;
+    }
+
+    /**
+     * The default implementation of ImageListener which handles basic functionality
+     * of showing a default image until the network response is received, at which point
+     * it will switch to either the actual image or the error image.
+     * @param imageView The imageView that the listener is associated with.
+     * @param defaultImageResId Default image resource ID to use, or 0 if it doesn't exist.
+     * @param errorImageResId Error image resource ID to use, or 0 if it doesn't exist.
+     */
+    public static ImageListener getImageListener(final ImageView view,
+            final int defaultImageResId, final int errorImageResId) {
+        return new ImageListener() {
+            @Override
+            public void onErrorResponse(VolleyError error) {
+                if (errorImageResId != 0) {
+                    view.setImageResource(errorImageResId);
+                }
+            }
+
+            @Override
+            public void onResponse(ImageContainer response, boolean isImmediate) {
+                if (response.getBitmap() != null) {
+                    view.setImageBitmap(response.getBitmap());
+                } else if (defaultImageResId != 0) {
+                    view.setImageResource(defaultImageResId);
+                }
+            }
+        };
+    }
+
+    /**
+     * Interface for the response handlers on image requests.
+     *
+     * The call flow is this:
+     * 1. Upon being  attached to a request, onResponse(response, true) will
+     * be invoked to reflect any cached data that was already available. If the
+     * data was available, response.getBitmap() will be non-null.
+     *
+     * 2. After a network response returns, only one of the following cases will happen:
+     *   - onResponse(response, false) will be called if the image was loaded.
+     *   or
+     *   - onErrorResponse will be called if there was an error loading the image.
+     */
+    public interface ImageListener extends ErrorListener {
+        /**
+         * Listens for non-error changes to the loading of the image request.
+         *
+         * @param response Holds all information pertaining to the request, as well
+         * as the bitmap (if it is loaded).
+         * @param isImmediate True if this was called during ImageLoader.get() variants.
+         * This can be used to differentiate between a cached image loading and a network
+         * image loading in order to, for example, run an animation to fade in network loaded
+         * images.
+         */
+        public void onResponse(ImageContainer response, boolean isImmediate);
+    }
+
+    /**
+     * Checks if the item is available in the cache.
+     * @param requestUrl The url of the remote image
+     * @param maxWidth The maximum width of the returned image.
+     * @param maxHeight The maximum height of the returned image.
+     * @return True if the item exists in cache, false otherwise.
+     */
+    public boolean isCached(String requestUrl, int maxWidth, int maxHeight) {
+        throwIfNotOnMainThread();
+
+        String cacheKey = getCacheKey(requestUrl, maxWidth, maxHeight);
+        return mCache.getBitmap(cacheKey) != null;
+    }
+
+    /**
+     * Returns an ImageContainer for the requested URL.
+     *
+     * The ImageContainer will contain either the specified default bitmap or the loaded bitmap.
+     * If the default was returned, the {@link ImageLoader} will be invoked when the
+     * request is fulfilled.
+     *
+     * @param requestUrl The URL of the image to be loaded.
+     * @param defaultImage Optional default image to return until the actual image is loaded.
+     */
+    public ImageContainer get(String requestUrl, final ImageListener listener) {
+        return get(requestUrl, listener, 0, 0);
+    }
+
+    /**
+     * Issues a bitmap request with the given URL if that image is not available
+     * in the cache, and returns a bitmap container that contains all of the data
+     * relating to the request (as well as the default image if the requested
+     * image is not available).
+     * @param requestUrl The url of the remote image
+     * @param imageListener The listener to call when the remote image is loaded
+     * @param maxWidth The maximum width of the returned image.
+     * @param maxHeight The maximum height of the returned image.
+     * @return A container object that contains all of the properties of the request, as well as
+     *     the currently available image (default if remote is not loaded).
+     */
+    public ImageContainer get(String requestUrl, ImageListener imageListener,
+            int maxWidth, int maxHeight) {
+        // only fulfill requests that were initiated from the main thread.
+        throwIfNotOnMainThread();
+
+        final String cacheKey = getCacheKey(requestUrl, maxWidth, maxHeight);
+
+        // Try to look up the request in the cache of remote images.
+        Bitmap cachedBitmap = mCache.getBitmap(cacheKey);
+        if (cachedBitmap != null) {
+            // Return the cached bitmap.
+            ImageContainer container = new ImageContainer(cachedBitmap, requestUrl, null, null);
+            imageListener.onResponse(container, true);
+            return container;
+        }
+
+        // The bitmap did not exist in the cache, fetch it!
+        ImageContainer imageContainer =
+                new ImageContainer(null, requestUrl, cacheKey, imageListener);
+
+        // Update the caller to let them know that they should use the default bitmap.
+        imageListener.onResponse(imageContainer, true);
+
+        // Check to see if a request is already in-flight.
+        BatchedImageRequest request = mInFlightRequests.get(cacheKey);
+        if (request != null) {
+            // If it is, add this request to the list of listeners.
+            request.addContainer(imageContainer);
+            return imageContainer;
+        }
+
+        // The request is not already in flight. Send the new request to the network and
+        // track it.
+        Request<Bitmap> newRequest = makeImageRequest(requestUrl, maxWidth, maxHeight, cacheKey);
+
+        mRequestQueue.add(newRequest);
+        mInFlightRequests.put(cacheKey,
+                new BatchedImageRequest(newRequest, imageContainer));
+        return imageContainer;
+    }
+
+    protected Request<Bitmap> makeImageRequest(String requestUrl, int maxWidth, int maxHeight, final String cacheKey) {
+        return new ImageRequest(requestUrl, new Listener<Bitmap>() {
+            @Override
+            public void onResponse(Bitmap response) {
+                onGetImageSuccess(cacheKey, response);
+            }
+        }, maxWidth, maxHeight,
+        Config.RGB_565, new ErrorListener() {
+            @Override
+            public void onErrorResponse(VolleyError error) {
+                onGetImageError(cacheKey, error);
+            }
+        });
+    }
+
+    /**
+     * Sets the amount of time to wait after the first response arrives before delivering all
+     * responses. Batching can be disabled entirely by passing in 0.
+     * @param newBatchedResponseDelayMs The time in milliseconds to wait.
+     */
+    public void setBatchedResponseDelay(int newBatchedResponseDelayMs) {
+        mBatchResponseDelayMs = newBatchedResponseDelayMs;
+    }
+
+    /**
+     * Handler for when an image was successfully loaded.
+     * @param cacheKey The cache key that is associated with the image request.
+     * @param response The bitmap that was returned from the network.
+     */
+    protected void onGetImageSuccess(String cacheKey, Bitmap response) {
+        // cache the image that was fetched.
+        mCache.putBitmap(cacheKey, response);
+
+        // remove the request from the list of in-flight requests.
+        BatchedImageRequest request = mInFlightRequests.remove(cacheKey);
+
+        if (request != null) {
+            // Update the response bitmap.
+            request.mResponseBitmap = response;
+
+            // Send the batched response
+            batchResponse(cacheKey, request);
+        }
+    }
+
+    /**
+     * Handler for when an image failed to load.
+     * @param cacheKey The cache key that is associated with the image request.
+     */
+    protected void onGetImageError(String cacheKey, VolleyError error) {
+        // Notify the requesters that something failed via a null result.
+        // Remove this request from the list of in-flight requests.
+        BatchedImageRequest request = mInFlightRequests.remove(cacheKey);
+
+        if (request != null) {
+            // Set the error for this request
+            request.setError(error);
+
+            // Send the batched response
+            batchResponse(cacheKey, request);
+        }
+    }
+
+    /**
+     * Container object for all of the data surrounding an image request.
+     */
+    public class ImageContainer {
+        /**
+         * The most relevant bitmap for the container. If the image was in cache, the
+         * Holder to use for the final bitmap (the one that pairs to the requested URL).
+         */
+        private Bitmap mBitmap;
+
+        private final ImageListener mListener;
+
+        /** The cache key that was associated with the request */
+        private final String mCacheKey;
+
+        /** The request URL that was specified */
+        private final String mRequestUrl;
+
+        /**
+         * Constructs a BitmapContainer object.
+         * @param bitmap The final bitmap (if it exists).
+         * @param requestUrl The requested URL for this container.
+         * @param cacheKey The cache key that identifies the requested URL for this container.
+         */
+        public ImageContainer(Bitmap bitmap, String requestUrl,
+                String cacheKey, ImageListener listener) {
+            mBitmap = bitmap;
+            mRequestUrl = requestUrl;
+            mCacheKey = cacheKey;
+            mListener = listener;
+        }
+
+        /**
+         * Releases interest in the in-flight request (and cancels it if no one else is listening).
+         */
+        public void cancelRequest() {
+            if (mListener == null) {
+                return;
+            }
+
+            BatchedImageRequest request = mInFlightRequests.get(mCacheKey);
+            if (request != null) {
+                boolean canceled = request.removeContainerAndCancelIfNecessary(this);
+                if (canceled) {
+                    mInFlightRequests.remove(mCacheKey);
+                }
+            } else {
+                // check to see if it is already batched for delivery.
+                request = mBatchedResponses.get(mCacheKey);
+                if (request != null) {
+                    request.removeContainerAndCancelIfNecessary(this);
+                    if (request.mContainers.size() == 0) {
+                        mBatchedResponses.remove(mCacheKey);
+                    }
+                }
+            }
+        }
+
+        /**
+         * Returns the bitmap associated with the request URL if it has been loaded, null otherwise.
+         */
+        public Bitmap getBitmap() {
+            return mBitmap;
+        }
+
+        /**
+         * Returns the requested URL for this container.
+         */
+        public String getRequestUrl() {
+            return mRequestUrl;
+        }
+    }
+
+    /**
+     * Wrapper class used to map a Request to the set of active ImageContainer objects that are
+     * interested in its results.
+     */
+    private class BatchedImageRequest {
+        /** The request being tracked */
+        private final Request<?> mRequest;
+
+        /** The result of the request being tracked by this item */
+        private Bitmap mResponseBitmap;
+
+        /** Error if one occurred for this response */
+        private VolleyError mError;
+
+        /** List of all of the active ImageContainers that are interested in the request */
+        private final LinkedList<ImageContainer> mContainers = new LinkedList<ImageContainer>();
+
+        /**
+         * Constructs a new BatchedImageRequest object
+         * @param request The request being tracked
+         * @param container The ImageContainer of the person who initiated the request.
+         */
+        public BatchedImageRequest(Request<?> request, ImageContainer container) {
+            mRequest = request;
+            mContainers.add(container);
+        }
+
+        /**
+         * Set the error for this response
+         */
+        public void setError(VolleyError error) {
+            mError = error;
+        }
+
+        /**
+         * Get the error for this response
+         */
+        public VolleyError getError() {
+            return mError;
+        }
+
+        /**
+         * Adds another ImageContainer to the list of those interested in the results of
+         * the request.
+         */
+        public void addContainer(ImageContainer container) {
+            mContainers.add(container);
+        }
+
+        /**
+         * Detatches the bitmap container from the request and cancels the request if no one is
+         * left listening.
+         * @param container The container to remove from the list
+         * @return True if the request was canceled, false otherwise.
+         */
+        public boolean removeContainerAndCancelIfNecessary(ImageContainer container) {
+            mContainers.remove(container);
+            if (mContainers.size() == 0) {
+                mRequest.cancel();
+                return true;
+            }
+            return false;
+        }
+    }
+
+    /**
+     * Starts the runnable for batched delivery of responses if it is not already started.
+     * @param cacheKey The cacheKey of the response being delivered.
+     * @param request The BatchedImageRequest to be delivered.
+     * @param error The volley error associated with the request (if applicable).
+     */
+    private void batchResponse(String cacheKey, BatchedImageRequest request) {
+        mBatchedResponses.put(cacheKey, request);
+        // If we don't already have a batch delivery runnable in flight, make a new one.
+        // Note that this will be used to deliver responses to all callers in mBatchedResponses.
+        if (mRunnable == null) {
+            mRunnable = new Runnable() {
+                @Override
+                public void run() {
+                    for (BatchedImageRequest bir : mBatchedResponses.values()) {
+                        for (ImageContainer container : bir.mContainers) {
+                            // If one of the callers in the batched request canceled the request
+                            // after the response was received but before it was delivered,
+                            // skip them.
+                            if (container.mListener == null) {
+                                continue;
+                            }
+                            if (bir.getError() == null) {
+                                container.mBitmap = bir.mResponseBitmap;
+                                container.mListener.onResponse(container, false);
+                            } else {
+                                container.mListener.onErrorResponse(bir.getError());
+                            }
+                        }
+                    }
+                    mBatchedResponses.clear();
+                    mRunnable = null;
+                }
+
+            };
+            // Post the runnable.
+            mHandler.postDelayed(mRunnable, mBatchResponseDelayMs);
+        }
+    }
+
+    private void throwIfNotOnMainThread() {
+        if (Looper.myLooper() != Looper.getMainLooper()) {
+            throw new IllegalStateException("ImageLoader must be invoked from the main thread.");
+        }
+    }
+    /**
+     * Creates a cache key for use with the L1 cache.
+     * @param url The URL of the request.
+     * @param maxWidth The max-width of the output.
+     * @param maxHeight The max-height of the output.
+     */
+    private static String getCacheKey(String url, int maxWidth, int maxHeight) {
+        return new StringBuilder(url.length() + 12).append("#W").append(maxWidth)
+                .append("#H").append(maxHeight).append(url).toString();
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/ImageRequest.java b/src/main/java/com/android/volley/toolbox/ImageRequest.java
new file mode 100644
index 0000000..2ebe015
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/ImageRequest.java
@@ -0,0 +1,211 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.DefaultRetryPolicy;
+import com.android.volley.NetworkResponse;
+import com.android.volley.ParseError;
+import com.android.volley.Request;
+import com.android.volley.Response;
+import com.android.volley.VolleyLog;
+
+import android.graphics.Bitmap;
+import android.graphics.Bitmap.Config;
+import android.graphics.BitmapFactory;
+
+/**
+ * A canned request for getting an image at a given URL and calling
+ * back with a decoded Bitmap.
+ */
+public class ImageRequest extends Request<Bitmap> {
+    /** Socket timeout in milliseconds for image requests */
+    private static final int IMAGE_TIMEOUT_MS = 1000;
+
+    /** Default number of retries for image requests */
+    private static final int IMAGE_MAX_RETRIES = 2;
+
+    /** Default backoff multiplier for image requests */
+    private static final float IMAGE_BACKOFF_MULT = 2f;
+
+    private final Response.Listener<Bitmap> mListener;
+    private final Config mDecodeConfig;
+    private final int mMaxWidth;
+    private final int mMaxHeight;
+
+    /** Decoding lock so that we don't decode more than one image at a time (to avoid OOM's) */
+    private static final Object sDecodeLock = new Object();
+
+    /**
+     * Creates a new image request, decoding to a maximum specified width and
+     * height. If both width and height are zero, the image will be decoded to
+     * its natural size. If one of the two is nonzero, that dimension will be
+     * clamped and the other one will be set to preserve the image's aspect
+     * ratio. If both width and height are nonzero, the image will be decoded to
+     * be fit in the rectangle of dimensions width x height while keeping its
+     * aspect ratio.
+     *
+     * @param url URL of the image
+     * @param listener Listener to receive the decoded bitmap
+     * @param maxWidth Maximum width to decode this bitmap to, or zero for none
+     * @param maxHeight Maximum height to decode this bitmap to, or zero for
+     *            none
+     * @param decodeConfig Format to decode the bitmap to
+     * @param errorListener Error listener, or null to ignore errors
+     */
+    public ImageRequest(String url, Response.Listener<Bitmap> listener, int maxWidth, int maxHeight,
+            Config decodeConfig, Response.ErrorListener errorListener) {
+        super(Method.GET, url, errorListener);
+        setRetryPolicy(
+                new DefaultRetryPolicy(IMAGE_TIMEOUT_MS, IMAGE_MAX_RETRIES, IMAGE_BACKOFF_MULT));
+        mListener = listener;
+        mDecodeConfig = decodeConfig;
+        mMaxWidth = maxWidth;
+        mMaxHeight = maxHeight;
+    }
+
+    @Override
+    public Priority getPriority() {
+        return Priority.LOW;
+    }
+
+    /**
+     * Scales one side of a rectangle to fit aspect ratio.
+     *
+     * @param maxPrimary Maximum size of the primary dimension (i.e. width for
+     *        max width), or zero to maintain aspect ratio with secondary
+     *        dimension
+     * @param maxSecondary Maximum size of the secondary dimension, or zero to
+     *        maintain aspect ratio with primary dimension
+     * @param actualPrimary Actual size of the primary dimension
+     * @param actualSecondary Actual size of the secondary dimension
+     */
+    private static int getResizedDimension(int maxPrimary, int maxSecondary, int actualPrimary,
+            int actualSecondary) {
+        // If no dominant value at all, just return the actual.
+        if (maxPrimary == 0 && maxSecondary == 0) {
+            return actualPrimary;
+        }
+
+        // If primary is unspecified, scale primary to match secondary's scaling ratio.
+        if (maxPrimary == 0) {
+            double ratio = (double) maxSecondary / (double) actualSecondary;
+            return (int) (actualPrimary * ratio);
+        }
+
+        if (maxSecondary == 0) {
+            return maxPrimary;
+        }
+
+        double ratio = (double) actualSecondary / (double) actualPrimary;
+        int resized = maxPrimary;
+        if (resized * ratio > maxSecondary) {
+            resized = (int) (maxSecondary / ratio);
+        }
+        return resized;
+    }
+
+    @Override
+    protected Response<Bitmap> parseNetworkResponse(NetworkResponse response) {
+        // Serialize all decode on a global lock to reduce concurrent heap usage.
+        synchronized (sDecodeLock) {
+            try {
+                return doParse(response);
+            } catch (OutOfMemoryError e) {
+                VolleyLog.e("Caught OOM for %d byte image, url=%s", response.data.length, getUrl());
+                return Response.error(new ParseError(e));
+            }
+        }
+    }
+
+    /**
+     * The real guts of parseNetworkResponse. Broken out for readability.
+     */
+    private Response<Bitmap> doParse(NetworkResponse response) {
+        byte[] data = response.data;
+        BitmapFactory.Options decodeOptions = new BitmapFactory.Options();
+        Bitmap bitmap = null;
+        if (mMaxWidth == 0 && mMaxHeight == 0) {
+            decodeOptions.inPreferredConfig = mDecodeConfig;
+            bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
+        } else {
+            // If we have to resize this image, first get the natural bounds.
+            decodeOptions.inJustDecodeBounds = true;
+            BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
+            int actualWidth = decodeOptions.outWidth;
+            int actualHeight = decodeOptions.outHeight;
+
+            // Then compute the dimensions we would ideally like to decode to.
+            int desiredWidth = getResizedDimension(mMaxWidth, mMaxHeight,
+                    actualWidth, actualHeight);
+            int desiredHeight = getResizedDimension(mMaxHeight, mMaxWidth,
+                    actualHeight, actualWidth);
+
+            // Decode to the nearest power of two scaling factor.
+            decodeOptions.inJustDecodeBounds = false;
+            // TODO(ficus): Do we need this or is it okay since API 8 doesn't support it?
+            // decodeOptions.inPreferQualityOverSpeed = PREFER_QUALITY_OVER_SPEED;
+            decodeOptions.inSampleSize =
+                findBestSampleSize(actualWidth, actualHeight, desiredWidth, desiredHeight);
+            Bitmap tempBitmap =
+                BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
+
+            // If necessary, scale down to the maximal acceptable size.
+            if (tempBitmap != null && (tempBitmap.getWidth() > desiredWidth ||
+                    tempBitmap.getHeight() > desiredHeight)) {
+                bitmap = Bitmap.createScaledBitmap(tempBitmap,
+                        desiredWidth, desiredHeight, true);
+                tempBitmap.recycle();
+            } else {
+                bitmap = tempBitmap;
+            }
+        }
+
+        if (bitmap == null) {
+            return Response.error(new ParseError(response));
+        } else {
+            return Response.success(bitmap, HttpHeaderParser.parseCacheHeaders(response));
+        }
+    }
+
+    @Override
+    protected void deliverResponse(Bitmap response) {
+        mListener.onResponse(response);
+    }
+
+    /**
+     * Returns the largest power-of-two divisor for use in downscaling a bitmap
+     * that will not result in the scaling past the desired dimensions.
+     *
+     * @param actualWidth Actual width of the bitmap
+     * @param actualHeight Actual height of the bitmap
+     * @param desiredWidth Desired width of the bitmap
+     * @param desiredHeight Desired height of the bitmap
+     */
+    // Visible for testing.
+    static int findBestSampleSize(
+            int actualWidth, int actualHeight, int desiredWidth, int desiredHeight) {
+        double wr = (double) actualWidth / desiredWidth;
+        double hr = (double) actualHeight / desiredHeight;
+        double ratio = Math.min(wr, hr);
+        float n = 1.0f;
+        while ((n * 2) <= ratio) {
+            n *= 2;
+        }
+
+        return (int) n;
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/JsonArrayRequest.java b/src/main/java/com/android/volley/toolbox/JsonArrayRequest.java
new file mode 100644
index 0000000..b1eae80
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/JsonArrayRequest.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.ParseError;
+import com.android.volley.Response;
+import com.android.volley.Response.ErrorListener;
+import com.android.volley.Response.Listener;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * A request for retrieving a {@link JSONArray} response body at a given URL.
+ */
+public class JsonArrayRequest extends JsonRequest<JSONArray> {
+
+    /**
+     * Creates a new request.
+     * @param url URL to fetch the JSON from
+     * @param listener Listener to receive the JSON response
+     * @param errorListener Error listener, or null to ignore errors.
+     */
+    public JsonArrayRequest(String url, Listener<JSONArray> listener, ErrorListener errorListener) {
+        super(Method.GET, url, null, listener, errorListener);
+    }
+
+    @Override
+    protected Response<JSONArray> parseNetworkResponse(NetworkResponse response) {
+        try {
+            String jsonString =
+                new String(response.data, HttpHeaderParser.parseCharset(response.headers));
+            return Response.success(new JSONArray(jsonString),
+                    HttpHeaderParser.parseCacheHeaders(response));
+        } catch (UnsupportedEncodingException e) {
+            return Response.error(new ParseError(e));
+        } catch (JSONException je) {
+            return Response.error(new ParseError(je));
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/JsonObjectRequest.java b/src/main/java/com/android/volley/toolbox/JsonObjectRequest.java
new file mode 100644
index 0000000..74821cb
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/JsonObjectRequest.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.ParseError;
+import com.android.volley.Response;
+import com.android.volley.Response.ErrorListener;
+import com.android.volley.Response.Listener;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * A request for retrieving a {@link JSONObject} response body at a given URL, allowing for an
+ * optional {@link JSONObject} to be passed in as part of the request body.
+ */
+public class JsonObjectRequest extends JsonRequest<JSONObject> {
+
+    /**
+     * Creates a new request.
+     * @param method the HTTP method to use
+     * @param url URL to fetch the JSON from
+     * @param jsonRequest A {@link JSONObject} to post with the request. Null is allowed and
+     *   indicates no parameters will be posted along with request.
+     * @param listener Listener to receive the JSON response
+     * @param errorListener Error listener, or null to ignore errors.
+     */
+    public JsonObjectRequest(int method, String url, JSONObject jsonRequest,
+            Listener<JSONObject> listener, ErrorListener errorListener) {
+        super(method, url, (jsonRequest == null) ? null : jsonRequest.toString(), listener,
+                    errorListener);
+    }
+
+    /**
+     * Constructor which defaults to <code>GET</code> if <code>jsonRequest</code> is
+     * <code>null</code>, <code>POST</code> otherwise.
+     *
+     * @see #JsonObjectRequest(int, String, JSONObject, Listener, ErrorListener)
+     */
+    public JsonObjectRequest(String url, JSONObject jsonRequest, Listener<JSONObject> listener,
+            ErrorListener errorListener) {
+        this(jsonRequest == null ? Method.GET : Method.POST, url, jsonRequest,
+                listener, errorListener);
+    }
+
+    @Override
+    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
+        try {
+            String jsonString =
+                new String(response.data, HttpHeaderParser.parseCharset(response.headers));
+            return Response.success(new JSONObject(jsonString),
+                    HttpHeaderParser.parseCacheHeaders(response));
+        } catch (UnsupportedEncodingException e) {
+            return Response.error(new ParseError(e));
+        } catch (JSONException je) {
+            return Response.error(new ParseError(je));
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/JsonRequest.java b/src/main/java/com/android/volley/toolbox/JsonRequest.java
new file mode 100644
index 0000000..f11ac14
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/JsonRequest.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.Request;
+import com.android.volley.Response;
+import com.android.volley.Response.ErrorListener;
+import com.android.volley.Response.Listener;
+import com.android.volley.VolleyLog;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * A request for retrieving a T type response body at a given URL that also
+ * optionally sends along a JSON body in the request specified.
+ *
+ * @param <T> JSON type of response expected
+ */
+public abstract class JsonRequest<T> extends Request<T> {
+    /** Charset for request. */
+    private static final String PROTOCOL_CHARSET = "utf-8";
+
+    /** Content type for request. */
+    private static final String PROTOCOL_CONTENT_TYPE =
+        String.format("application/json; charset=%s", PROTOCOL_CHARSET);
+
+    private final Listener<T> mListener;
+    private final String mRequestBody;
+
+    /**
+     * Deprecated constructor for a JsonRequest which defaults to GET unless {@link #getPostBody()}
+     * or {@link #getPostParams()} is overridden (which defaults to POST).
+     *
+     * @deprecated Use {@link #JsonRequest(int, String, String, Listener, ErrorListener)}.
+     */
+    public JsonRequest(String url, String requestBody, Listener<T> listener,
+            ErrorListener errorListener) {
+        this(Method.DEPRECATED_GET_OR_POST, url, requestBody, listener, errorListener);
+    }
+
+    public JsonRequest(int method, String url, String requestBody, Listener<T> listener,
+            ErrorListener errorListener) {
+        super(method, url, errorListener);
+        mListener = listener;
+        mRequestBody = requestBody;
+    }
+
+    @Override
+    protected void deliverResponse(T response) {
+        mListener.onResponse(response);
+    }
+
+    @Override
+    abstract protected Response<T> parseNetworkResponse(NetworkResponse response);
+
+    /**
+     * @deprecated Use {@link #getBodyContentType()}.
+     */
+    @Override
+    public String getPostBodyContentType() {
+        return getBodyContentType();
+    }
+
+    /**
+     * @deprecated Use {@link #getBody()}.
+     */
+    @Override
+    public byte[] getPostBody() {
+        return getBody();
+    }
+
+    @Override
+    public String getBodyContentType() {
+        return PROTOCOL_CONTENT_TYPE;
+    }
+
+    @Override
+    public byte[] getBody() {
+        try {
+            return mRequestBody == null ? null : mRequestBody.getBytes(PROTOCOL_CHARSET);
+        } catch (UnsupportedEncodingException uee) {
+            VolleyLog.wtf("Unsupported Encoding while trying to get the bytes of %s using %s",
+                    mRequestBody, PROTOCOL_CHARSET);
+            return null;
+        }
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/NetworkImageView.java b/src/main/java/com/android/volley/toolbox/NetworkImageView.java
new file mode 100644
index 0000000..692e988
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/NetworkImageView.java
@@ -0,0 +1,219 @@
+/**
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.volley.toolbox;
+
+import android.content.Context;
+import android.text.TextUtils;
+import android.util.AttributeSet;
+import android.view.ViewGroup.LayoutParams;
+import android.widget.ImageView;
+
+import com.android.volley.VolleyError;
+import com.android.volley.toolbox.ImageLoader.ImageContainer;
+import com.android.volley.toolbox.ImageLoader.ImageListener;
+
+/**
+ * Handles fetching an image from a URL as well as the life-cycle of the
+ * associated request.
+ */
+public class NetworkImageView extends ImageView {
+    /** The URL of the network image to load */
+    private String mUrl;
+
+    /**
+     * Resource ID of the image to be used as a placeholder until the network image is loaded.
+     */
+    private int mDefaultImageId;
+
+    /**
+     * Resource ID of the image to be used if the network response fails.
+     */
+    private int mErrorImageId;
+
+    /** Local copy of the ImageLoader. */
+    private ImageLoader mImageLoader;
+
+    /** Current ImageContainer. (either in-flight or finished) */
+    private ImageContainer mImageContainer;
+
+    public NetworkImageView(Context context) {
+        this(context, null);
+    }
+
+    public NetworkImageView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public NetworkImageView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    /**
+     * Sets URL of the image that should be loaded into this view. Note that calling this will
+     * immediately either set the cached image (if available) or the default image specified by
+     * {@link NetworkImageView#setDefaultImageResId(int)} on the view.
+     *
+     * NOTE: If applicable, {@link NetworkImageView#setDefaultImageResId(int)} and
+     * {@link NetworkImageView#setErrorImageResId(int)} should be called prior to calling
+     * this function.
+     *
+     * @param url The URL that should be loaded into this ImageView.
+     * @param imageLoader ImageLoader that will be used to make the request.
+     */
+    public void setImageUrl(String url, ImageLoader imageLoader) {
+        mUrl = url;
+        mImageLoader = imageLoader;
+        // The URL has potentially changed. See if we need to load it.
+        loadImageIfNecessary(false);
+    }
+
+    /**
+     * Sets the default image resource ID to be used for this view until the attempt to load it
+     * completes.
+     */
+    public void setDefaultImageResId(int defaultImage) {
+        mDefaultImageId = defaultImage;
+    }
+
+    /**
+     * Sets the error image resource ID to be used for this view in the event that the image
+     * requested fails to load.
+     */
+    public void setErrorImageResId(int errorImage) {
+        mErrorImageId = errorImage;
+    }
+
+    /**
+     * Loads the image for the view if it isn't already loaded.
+     * @param isInLayoutPass True if this was invoked from a layout pass, false otherwise.
+     */
+    void loadImageIfNecessary(final boolean isInLayoutPass) {
+        int width = getWidth();
+        int height = getHeight();
+
+        boolean wrapWidth = false, wrapHeight = false;
+        if (getLayoutParams() != null) {
+            wrapWidth = getLayoutParams().width == LayoutParams.WRAP_CONTENT;
+            wrapHeight = getLayoutParams().height == LayoutParams.WRAP_CONTENT;
+        }
+
+        // if the view's bounds aren't known yet, and this is not a wrap-content/wrap-content
+        // view, hold off on loading the image.
+        boolean isFullyWrapContent = wrapWidth && wrapHeight;
+        if (width == 0 && height == 0 && !isFullyWrapContent) {
+            return;
+        }
+
+        // if the URL to be loaded in this view is empty, cancel any old requests and clear the
+        // currently loaded image.
+        if (TextUtils.isEmpty(mUrl)) {
+            if (mImageContainer != null) {
+                mImageContainer.cancelRequest();
+                mImageContainer = null;
+            }
+            setDefaultImageOrNull();
+            return;
+        }
+
+        // if there was an old request in this view, check if it needs to be canceled.
+        if (mImageContainer != null && mImageContainer.getRequestUrl() != null) {
+            if (mImageContainer.getRequestUrl().equals(mUrl)) {
+                // if the request is from the same URL, return.
+                return;
+            } else {
+                // if there is a pre-existing request, cancel it if it's fetching a different URL.
+                mImageContainer.cancelRequest();
+                setDefaultImageOrNull();
+            }
+        }
+
+        // Calculate the max image width / height to use while ignoring WRAP_CONTENT dimens.
+        int maxWidth = wrapWidth ? 0 : width;
+        int maxHeight = wrapHeight ? 0 : height;
+
+        // The pre-existing content of this view didn't match the current URL. Load the new image
+        // from the network.
+        ImageContainer newContainer = mImageLoader.get(mUrl,
+                new ImageListener() {
+                    @Override
+                    public void onErrorResponse(VolleyError error) {
+                        if (mErrorImageId != 0) {
+                            setImageResource(mErrorImageId);
+                        }
+                    }
+
+                    @Override
+                    public void onResponse(final ImageContainer response, boolean isImmediate) {
+                        // If this was an immediate response that was delivered inside of a layout
+                        // pass do not set the image immediately as it will trigger a requestLayout
+                        // inside of a layout. Instead, defer setting the image by posting back to
+                        // the main thread.
+                        if (isImmediate && isInLayoutPass) {
+                            post(new Runnable() {
+                                @Override
+                                public void run() {
+                                    onResponse(response, false);
+                                }
+                            });
+                            return;
+                        }
+
+                        if (response.getBitmap() != null) {
+                            setImageBitmap(response.getBitmap());
+                        } else if (mDefaultImageId != 0) {
+                            setImageResource(mDefaultImageId);
+                        }
+                    }
+                }, maxWidth, maxHeight);
+
+        // update the ImageContainer to be the new bitmap container.
+        mImageContainer = newContainer;
+    }
+
+    private void setDefaultImageOrNull() {
+        if(mDefaultImageId != 0) {
+            setImageResource(mDefaultImageId);
+        }
+        else {
+            setImageBitmap(null);
+        }
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        super.onLayout(changed, left, top, right, bottom);
+        loadImageIfNecessary(true);
+    }
+
+    @Override
+    protected void onDetachedFromWindow() {
+        if (mImageContainer != null) {
+            // If the view was bound to an image request, cancel it and clear
+            // out the image from the view.
+            mImageContainer.cancelRequest();
+            setImageBitmap(null);
+            // also clear out the container so we can reload the image if necessary.
+            mImageContainer = null;
+        }
+        super.onDetachedFromWindow();
+    }
+
+    @Override
+    protected void drawableStateChanged() {
+        super.drawableStateChanged();
+        invalidate();
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/NoCache.java b/src/main/java/com/android/volley/toolbox/NoCache.java
new file mode 100644
index 0000000..ab66254
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/NoCache.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.Cache;
+
+/**
+ * A cache that doesn't.
+ */
+public class NoCache implements Cache {
+    @Override
+    public void clear() {
+    }
+
+    @Override
+    public Entry get(String key) {
+        return null;
+    }
+
+    @Override
+    public void put(String key, Entry entry) {
+    }
+
+    @Override
+    public void invalidate(String key, boolean fullExpire) {
+    }
+
+    @Override
+    public void remove(String key) {
+    }
+
+    @Override
+    public void initialize() {
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java b/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java
new file mode 100644
index 0000000..9971566
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/PoolingByteArrayOutputStream.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+/**
+ * A variation of {@link java.io.ByteArrayOutputStream} that uses a pool of byte[] buffers instead
+ * of always allocating them fresh, saving on heap churn.
+ */
+public class PoolingByteArrayOutputStream extends ByteArrayOutputStream {
+    /**
+     * If the {@link #PoolingByteArrayOutputStream(ByteArrayPool)} constructor is called, this is
+     * the default size to which the underlying byte array is initialized.
+     */
+    private static final int DEFAULT_SIZE = 256;
+
+    private final ByteArrayPool mPool;
+
+    /**
+     * Constructs a new PoolingByteArrayOutputStream with a default size. If more bytes are written
+     * to this instance, the underlying byte array will expand.
+     */
+    public PoolingByteArrayOutputStream(ByteArrayPool pool) {
+        this(pool, DEFAULT_SIZE);
+    }
+
+    /**
+     * Constructs a new {@code ByteArrayOutputStream} with a default size of {@code size} bytes. If
+     * more than {@code size} bytes are written to this instance, the underlying byte array will
+     * expand.
+     *
+     * @param size initial size for the underlying byte array. The value will be pinned to a default
+     *        minimum size.
+     */
+    public PoolingByteArrayOutputStream(ByteArrayPool pool, int size) {
+        mPool = pool;
+        buf = mPool.getBuf(Math.max(size, DEFAULT_SIZE));
+    }
+
+    @Override
+    public void close() throws IOException {
+        mPool.returnBuf(buf);
+        buf = null;
+        super.close();
+    }
+
+    @Override
+    public void finalize() {
+        mPool.returnBuf(buf);
+    }
+
+    /**
+     * Ensures there is enough space in the buffer for the given number of additional bytes.
+     */
+    private void expand(int i) {
+        /* Can the buffer handle @i more bytes, if not expand it */
+        if (count + i <= buf.length) {
+            return;
+        }
+        byte[] newbuf = mPool.getBuf((count + i) * 2);
+        System.arraycopy(buf, 0, newbuf, 0, count);
+        mPool.returnBuf(buf);
+        buf = newbuf;
+    }
+
+    @Override
+    public synchronized void write(byte[] buffer, int offset, int len) {
+        expand(len);
+        super.write(buffer, offset, len);
+    }
+
+    @Override
+    public synchronized void write(int oneByte) {
+        expand(1);
+        super.write(oneByte);
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/RequestFuture.java b/src/main/java/com/android/volley/toolbox/RequestFuture.java
new file mode 100644
index 0000000..173c44c
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/RequestFuture.java
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.Request;
+import com.android.volley.Response;
+import com.android.volley.VolleyError;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/**
+ * A Future that represents a Volley request.
+ *
+ * Used by providing as your response and error listeners. For example:
+ * <pre>
+ * RequestFuture&lt;JSONObject&gt; future = RequestFuture.newFuture();
+ * MyRequest request = new MyRequest(URL, future, future);
+ *
+ * // If you want to be able to cancel the request:
+ * future.setRequest(requestQueue.add(request));
+ *
+ * // Otherwise:
+ * requestQueue.add(request);
+ *
+ * try {
+ *   JSONObject response = future.get();
+ *   // do something with response
+ * } catch (InterruptedException e) {
+ *   // handle the error
+ * } catch (ExecutionException e) {
+ *   // handle the error
+ * }
+ * </pre>
+ *
+ * @param <T> The type of parsed response this future expects.
+ */
+public class RequestFuture<T> implements Future<T>, Response.Listener<T>,
+       Response.ErrorListener {
+    private Request<?> mRequest;
+    private boolean mResultReceived = false;
+    private T mResult;
+    private VolleyError mException;
+
+    public static <E> RequestFuture<E> newFuture() {
+        return new RequestFuture<E>();
+    }
+
+    private RequestFuture() {}
+
+    public void setRequest(Request<?> request) {
+        mRequest = request;
+    }
+
+    @Override
+    public synchronized boolean cancel(boolean mayInterruptIfRunning) {
+        if (mRequest == null) {
+            return false;
+        }
+
+        if (!isDone()) {
+            mRequest.cancel();
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    @Override
+    public T get() throws InterruptedException, ExecutionException {
+        try {
+            return doGet(null);
+        } catch (TimeoutException e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    @Override
+    public T get(long timeout, TimeUnit unit)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        return doGet(TimeUnit.MILLISECONDS.convert(timeout, unit));
+    }
+
+    private synchronized T doGet(Long timeoutMs)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        if (mException != null) {
+            throw new ExecutionException(mException);
+        }
+
+        if (mResultReceived) {
+            return mResult;
+        }
+
+        if (timeoutMs == null) {
+            wait(0);
+        } else if (timeoutMs > 0) {
+            wait(timeoutMs);
+        }
+
+        if (mException != null) {
+            throw new ExecutionException(mException);
+        }
+
+        if (!mResultReceived) {
+            throw new TimeoutException();
+        }
+
+        return mResult;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        if (mRequest == null) {
+            return false;
+        }
+        return mRequest.isCanceled();
+    }
+
+    @Override
+    public synchronized boolean isDone() {
+        return mResultReceived || mException != null || isCancelled();
+    }
+
+    @Override
+    public synchronized void onResponse(T response) {
+        mResultReceived = true;
+        mResult = response;
+        notifyAll();
+    }
+
+    @Override
+    public synchronized void onErrorResponse(VolleyError error) {
+        mException = error;
+        notifyAll();
+    }
+}
+
diff --git a/src/main/java/com/android/volley/toolbox/StringRequest.java b/src/main/java/com/android/volley/toolbox/StringRequest.java
new file mode 100644
index 0000000..6b3dfcf
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/StringRequest.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import com.android.volley.NetworkResponse;
+import com.android.volley.Request;
+import com.android.volley.Response;
+import com.android.volley.Response.ErrorListener;
+import com.android.volley.Response.Listener;
+
+import java.io.UnsupportedEncodingException;
+
+/**
+ * A canned request for retrieving the response body at a given URL as a String.
+ */
+public class StringRequest extends Request<String> {
+    private final Listener<String> mListener;
+
+    /**
+     * Creates a new request with the given method.
+     *
+     * @param method the request {@link Method} to use
+     * @param url URL to fetch the string at
+     * @param listener Listener to receive the String response
+     * @param errorListener Error listener, or null to ignore errors
+     */
+    public StringRequest(int method, String url, Listener<String> listener,
+            ErrorListener errorListener) {
+        super(method, url, errorListener);
+        mListener = listener;
+    }
+
+    /**
+     * Creates a new GET request.
+     *
+     * @param url URL to fetch the string at
+     * @param listener Listener to receive the String response
+     * @param errorListener Error listener, or null to ignore errors
+     */
+    public StringRequest(String url, Listener<String> listener, ErrorListener errorListener) {
+        this(Method.GET, url, listener, errorListener);
+    }
+
+    @Override
+    protected void deliverResponse(String response) {
+        mListener.onResponse(response);
+    }
+
+    @Override
+    protected Response<String> parseNetworkResponse(NetworkResponse response) {
+        String parsed;
+        try {
+            parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
+        } catch (UnsupportedEncodingException e) {
+            parsed = new String(response.data);
+        }
+        return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));
+    }
+}
diff --git a/src/main/java/com/android/volley/toolbox/Volley.java b/src/main/java/com/android/volley/toolbox/Volley.java
new file mode 100644
index 0000000..0e04e87
--- /dev/null
+++ b/src/main/java/com/android/volley/toolbox/Volley.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.volley.toolbox;
+
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.net.http.AndroidHttpClient;
+import android.os.Build;
+
+import com.android.volley.Network;
+import com.android.volley.RequestQueue;
+
+import java.io.File;
+
+public class Volley {
+
+    /** Default on-disk cache directory. */
+    private static final String DEFAULT_CACHE_DIR = "volley";
+
+    /**
+     * Creates a default instance of the worker pool and calls {@link RequestQueue#start()} on it.
+     *
+     * @param context A {@link Context} to use for creating the cache dir.
+     * @param stack An {@link HttpStack} to use for the network, or null for default.
+     * @return A started {@link RequestQueue} instance.
+     */
+    public static RequestQueue newRequestQueue(Context context, HttpStack stack) {
+        File cacheDir = new File(context.getCacheDir(), DEFAULT_CACHE_DIR);
+
+        String userAgent = "volley/0";
+        try {
+            String packageName = context.getPackageName();
+            PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);
+            userAgent = packageName + "/" + info.versionCode;
+        } catch (NameNotFoundException e) {
+        }
+
+        if (stack == null) {
+            if (Build.VERSION.SDK_INT >= 9) {
+                stack = new HurlStack();
+            } else {
+                // Prior to Gingerbread, HttpUrlConnection was unreliable.
+                // See: http://android-developers.blogspot.com/2011/09/androids-http-clients.html
+                stack = new HttpClientStack(AndroidHttpClient.newInstance(userAgent));
+            }
+        }
+
+        Network network = new BasicNetwork(stack);
+
+        RequestQueue queue = new RequestQueue(new DiskBasedCache(cacheDir), network);
+        queue.start();
+
+        return queue;
+    }
+
+    /**
+     * Creates a default instance of the worker pool and calls {@link RequestQueue#start()} on it.
+     *
+     * @param context A {@link Context} to use for creating the cache dir.
+     * @return A started {@link RequestQueue} instance.
+     */
+    public static RequestQueue newRequestQueue(Context context) {
+        return newRequestQueue(context, null);
+    }
+}