break circular reference between UiElement and dom Element

add FileUtils.getAbsoluteFile

Change-Id: I278edbd60018ba230e966f5ce48cb582a98db44f

2 files changed, 27 insertions, 9 deletions

diff --git a/src/com/google/android/droiddriver/base/AbstractUiElement.java b/src/com/google/android/droiddriver/base/AbstractUiElement.java
index 3b35844..9c26bb4 100644
--- a/src/com/google/android/droiddriver/base/AbstractUiElement.java
+++ b/src/com/google/android/droiddriver/base/AbstractUiElement.java
@@ -32,11 +32,13 @@ import com.google.common.base.Objects.ToStringHelper;
 
 import org.w3c.dom.Element;
 
+import java.lang.ref.WeakReference;
+
 /**
  * Abstract implementation with common methods already implemented.
  */
 public abstract class AbstractUiElement implements UiElement {
-  private Element domNode;
+  private WeakReference<Element> domNode;
 
   @Override
   public <T> T get(Attribute attribute) {
@@ -120,11 +122,15 @@ public abstract class AbstractUiElement implements UiElement {
   /**
    * Used internally in {@link ByXPath}. Returns the DOM node representing this
    * UiElement. The DOM is constructed from the UiElement tree.
+   * <p>
+   * TODO: move this to {@link ByXPath}. This requires a BiMap using
+   * WeakReference for both keys and values, which is error-prone. This will be
+   * deferred until we decide whether to clear cache upon getRootElement.
    */
   public Element getDomNode() {
-    if (domNode == null) {
-      domNode = ByXPath.buildDomNode(this);
+    if (domNode == null || domNode.get() == null) {
+      domNode = new WeakReference<Element>(ByXPath.buildDomNode(this));
     }
-    return domNode;
+    return domNode.get();
   }
 }
diff --git a/src/com/google/android/droiddriver/util/FileUtils.java b/src/com/google/android/droiddriver/util/FileUtils.java
index a18d61a..5ffe681 100644
--- a/src/com/google/android/droiddriver/util/FileUtils.java
+++ b/src/com/google/android/droiddriver/util/FileUtils.java
@@ -34,11 +34,7 @@ public class FileUtils {
    * not exist, they will be created. The file will be readable to all.
    */
   public static BufferedOutputStream open(String path) throws FileNotFoundException {
-    File file = new File(path);
-    if (!file.isAbsolute()) {
-      file = new File(System.getProperty("java.io.tmpdir"), path);
-    }
-    mkdirs(file.getParentFile());
+    File file = getAbsoluteFile(path);
 
     Logs.log(Log.INFO, "opening file " + file.getAbsolutePath());
     BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(file));
@@ -46,6 +42,22 @@ public class FileUtils {
     return stream;
   }
 
+  /**
+   * Returns a new file constructed using the absolute path of {@code path}.
+   * Unlike {@link File#getAbsoluteFile()}, default parent is "java.io.tmpdir"
+   * instead of "user.dir".
+   * <p>
+   * If any directories on {@code path} do not exist, they will be created.
+   */
+  public static File getAbsoluteFile(String path) {
+    File file = new File(path);
+    if (!file.isAbsolute()) {
+      file = new File(System.getProperty("java.io.tmpdir"), path);
+    }
+    mkdirs(file.getParentFile());
+    return file;
+  }
+
   private static void mkdirs(File dir) {
     if (dir == null || dir.exists()) {
       return;