Improve DataSource implementations:

1. Make DefaultUriDataSource robust against exceptions through from close().
2. Make AssetDataSource handle file:///android_asset/ URIs.

library/src/main/java/com/google/android/exoplayer/upstream/AssetDataSource.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer.upstream;
 
 import com.google.android.exoplayer.C;
+import com.google.android.exoplayer.util.Assertions;
 
 import android.content.res.AssetManager;
 
@@ -24,9 +25,9 @@ import java.io.IOException;
 import java.io.InputStream;
 
 /**
- * A local asset {@link DataSource}.
+ * A local asset {@link UriDataSource}.
  */
-public final class AssetDataSource implements DataSource {
+public final class AssetDataSource implements UriDataSource {
 
   /**
    * Thrown when IOException is encountered during local asset read operation.
@@ -42,6 +43,7 @@ public final class AssetDataSource implements DataSource {
   private final AssetManager assetManager;
   private final TransferListener listener;
 
+  private String uriString;
   private InputStream assetInputStream;
   private long bytesRemaining;
   private boolean opened;
@@ -66,10 +68,16 @@ public final class AssetDataSource implements DataSource {
   @Override
   public long open(DataSpec dataSpec) throws AssetDataSourceException {
     try {
-      // Lose the '/' prefix in the path or else AssetManager won't find our file
-      assetInputStream = assetManager.open(dataSpec.uri.getPath().substring(1),
-          AssetManager.ACCESS_RANDOM);
-      assetInputStream.skip(dataSpec.position);
+      uriString = dataSpec.uri.toString();
+      String path = dataSpec.uri.getPath();
+      if (path.startsWith("/android_asset/")) {
+        path = path.substring(15);
+      } else if (path.startsWith("/")) {
+        path = path.substring(1);
+      }
+      assetInputStream = assetManager.open(path, AssetManager.ACCESS_RANDOM);
+      long skipped = assetInputStream.skip(dataSpec.position);
+      Assertions.checkState(skipped == dataSpec.position);
       bytesRemaining = dataSpec.length == C.LENGTH_UNBOUNDED ? assetInputStream.available()
           : dataSpec.length;
       if (bytesRemaining < 0) {
@@ -111,6 +119,11 @@ public final class AssetDataSource implements DataSource {
   }
 
   @Override
+  public String getUri() {
+    return uriString;
+  }
+
+  @Override
   public void close() throws AssetDataSourceException {
     if (assetInputStream != null) {
       try {

library/src/main/java/com/google/android/exoplayer/upstream/DefaultUriDataSource.java

@@ -100,8 +100,11 @@ public final class DefaultUriDataSource implements UriDataSource {
   @Override
   public void close() throws IOException {
     if (dataSource != null) {
-      dataSource.close();
-      dataSource = null;
+      try {
+        dataSource.close();
+      } finally {
+        dataSource = null;
+      }
     }
   }
 

library/src/main/java/com/google/android/exoplayer/upstream/FileDataSource.java

@@ -22,7 +22,7 @@ import java.io.IOException;
 import java.io.RandomAccessFile;
 
 /**
- * A local file {@link DataSource}.
+ * A local file {@link UriDataSource}.
  */
 public final class FileDataSource implements UriDataSource {
 

library/src/main/java/com/google/android/exoplayer/upstream/HttpDataSource.java

@@ -25,7 +25,7 @@ import java.util.List;
 import java.util.Map;
 
 /**
- * An HTTP specific extension to {@link DataSource}.
+ * An HTTP specific extension to {@link UriDataSource}.
  */
 public interface HttpDataSource extends UriDataSource {