diff options
Diffstat (limited to 'jimfs/src/main/java/com/google/common/jimfs/Handler.java')
-rw-r--r-- | jimfs/src/main/java/com/google/common/jimfs/Handler.java | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/jimfs/src/main/java/com/google/common/jimfs/Handler.java b/jimfs/src/main/java/com/google/common/jimfs/Handler.java new file mode 100644 index 0000000..fd4ab74 --- /dev/null +++ b/jimfs/src/main/java/com/google/common/jimfs/Handler.java @@ -0,0 +1,92 @@ +/* + * Copyright 2015 Google Inc. + * + * 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.google.common.jimfs; + +import static com.google.common.base.Preconditions.checkArgument; + +import java.io.IOException; +import java.net.InetAddress; +import java.net.URL; +import java.net.URLConnection; +import java.net.URLStreamHandler; + +/** + * {@link URLStreamHandler} implementation for jimfs. Named {@code Handler} so that the class can be + * found by Java as described in the documentation for {@link URL#URL(String, String, int, String) + * URL}. + * + * <p>This class is only public because it is necessary for Java to find it. It is not intended to + * be used directly. + * + * @author Colin Decker + * @since 1.1 + */ +public final class Handler extends URLStreamHandler { + + private static final String JAVA_PROTOCOL_HANDLER_PACKAGES = "java.protocol.handler.pkgs"; + + /** + * Registers this handler by adding the package {@code com.google.common} to the system property + * {@code "java.protocol.handler.pkgs"}. Java will then look for this class in the {@code jimfs} + * (the name of the protocol) package of {@code com.google.common}. + * + * @throws SecurityException if the system property that needs to be set to register this handler + * can't be read or written. + */ + static void register() { + register(Handler.class); + } + + /** Generic method that would allow registration of any properly placed {@code Handler} class. */ + static void register(Class<? extends URLStreamHandler> handlerClass) { + checkArgument("Handler".equals(handlerClass.getSimpleName())); + + String pkg = handlerClass.getPackage().getName(); + int lastDot = pkg.lastIndexOf('.'); + checkArgument(lastDot > 0, "package for Handler (%s) must have a parent package", pkg); + + String parentPackage = pkg.substring(0, lastDot); + + String packages = System.getProperty(JAVA_PROTOCOL_HANDLER_PACKAGES); + if (packages == null) { + packages = parentPackage; + } else { + packages += "|" + parentPackage; + } + System.setProperty(JAVA_PROTOCOL_HANDLER_PACKAGES, packages); + } + + /** @deprecated Not intended to be called directly; this class is only for use by Java itself. */ + @Deprecated + public Handler() {} // a public, no-arg constructor is required + + @Override + protected URLConnection openConnection(URL url) throws IOException { + return new PathURLConnection(url); + } + + @Override + @SuppressWarnings("UnsynchronizedOverridesSynchronized") // no need to synchronize to return null + protected InetAddress getHostAddress(URL url) { + // jimfs uses the URI host to specify the name of the file system being used. + // In the default implementation of getHostAddress(URL), a non-null host would cause an attempt + // to look up the IP address, causing a slowdown on calling equals/hashCode methods on the URL + // object. By returning null, we speed up equality checks on URL's (since there isn't an IP to + // connect to). + return null; + } +} |