Support raw resources inside the APK as a DataSource.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133013132

library/src/main/java/com/google/android/exoplayer2/upstream/RawResourceDataSource.java

+/*
+ * Copyright (C) 2016 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.google.android.exoplayer2.upstream;
+
+import android.content.Context;
+import android.content.res.AssetFileDescriptor;
+import android.content.res.Resources;
+import android.net.Uri;
+import android.text.TextUtils;
+
+import com.google.android.exoplayer2.C;
+import java.io.EOFException;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * A {@link DataSource} for reading a raw resource inside the APK.
+ * <p>
+ * URIs supported by this source are of the form {@code rawresource:///resourceId}, where resourceId
+ * is the integer identifier of a raw resource.
+ */
+public final class RawResourceDataSource implements DataSource {
+
+  /**
+   * Thrown when an {@link IOException} is encountered reading from a raw resource.
+   */
+  public static class RawResourceDataSourceException extends IOException {
+    public RawResourceDataSourceException(String message) {
+      super(message);
+    }
+
+    public RawResourceDataSourceException(IOException e) {
+      super(e);
+    }
+  }
+
+  /**
+   * The URI scheme used to identify raw resources. URIs used with this class must use this scheme.
+   */
+  public static final String RAW_RESOURCE_SCHEME = "rawresource";
+
+  private final Resources resources;
+  private final TransferListener<? super RawResourceDataSource> listener;
+
+  private Uri uri;
+  private AssetFileDescriptor assetFileDescriptor;
+  private InputStream inputStream;
+  private long bytesRemaining;
+  private boolean opened;
+
+  /**
+   * @param context A context.
+   */
+  public RawResourceDataSource(Context context) {
+    this(context, null);
+  }
+
+  /**
+   * @param context A context.
+   * @param listener An optional listener.
+   */
+  public RawResourceDataSource(Context context,
+      TransferListener<? super RawResourceDataSource> listener) {
+    this.resources = context.getResources();
+    this.listener = listener;
+  }
+
+  @Override
+  public long open(DataSpec dataSpec) throws RawResourceDataSourceException {
+    try {
+      uri = dataSpec.uri;
+      if (!TextUtils.equals(RAW_RESOURCE_SCHEME, uri.getScheme())) {
+        throw new RawResourceDataSourceException("URI must use scheme " + RAW_RESOURCE_SCHEME);
+      }
+
+      int resourceId;
+      try {
+        resourceId = Integer.parseInt(uri.getLastPathSegment());
+      } catch (NumberFormatException e) {
+        throw new RawResourceDataSourceException("Resource identifier must be an integer.");
+      }
+
+      assetFileDescriptor = resources.openRawResourceFd(resourceId);
+      inputStream = new FileInputStream(assetFileDescriptor.getFileDescriptor());
+      inputStream.skip(assetFileDescriptor.getStartOffset());
+      long skipped = inputStream.skip(dataSpec.position);
+      if (skipped < dataSpec.position) {
+        // We expect the skip to be satisfied in full. If it isn't then we're probably trying to
+        // skip beyond the end of the data.
+        throw new EOFException();
+      }
+      if (dataSpec.length != C.LENGTH_UNSET) {
+        bytesRemaining = dataSpec.length;
+      } else {
+        bytesRemaining = inputStream.available();
+        if (bytesRemaining == 0) {
+          // FileInputStream.available() returns 0 if the remaining length cannot be determined, or
+          // if it's greater than Integer.MAX_VALUE. We don't know the true length in either case,
+          // so treat as unbounded.
+          bytesRemaining = C.LENGTH_UNSET;
+        }
+      }
+    } catch (IOException e) {
+      throw new RawResourceDataSourceException(e);
+    }
+
+    opened = true;
+    if (listener != null) {
+      listener.onTransferStart(this, dataSpec);
+    }
+
+    return bytesRemaining;
+  }
+
+  @Override
+  public int read(byte[] buffer, int offset, int readLength) throws RawResourceDataSourceException {
+    if (bytesRemaining == 0) {
+      return C.RESULT_END_OF_INPUT;
+    } else {
+      int bytesRead;
+      try {
+        int bytesToRead = bytesRemaining == C.LENGTH_UNSET ? readLength
+            : (int) Math.min(bytesRemaining, readLength);
+        bytesRead = inputStream.read(buffer, offset, bytesToRead);
+      } catch (IOException e) {
+        throw new RawResourceDataSourceException(e);
+      }
+
+      if (bytesRead > 0) {
+        if (bytesRemaining != C.LENGTH_UNSET) {
+          bytesRemaining -= bytesRead;
+        }
+        if (listener != null) {
+          listener.onBytesTransferred(this, bytesRead);
+        }
+      }
+
+      return bytesRead;
+    }
+  }
+
+  @Override
+  public Uri getUri() {
+    return uri;
+  }
+
+  @Override
+  public void close() throws RawResourceDataSourceException {
+    uri = null;
+    try {
+      if (inputStream != null) {
+        inputStream.close();
+      }
+    } catch (IOException e) {
+      throw new RawResourceDataSourceException(e);
+    } finally {
+      inputStream = null;
+      try {
+        if (assetFileDescriptor != null) {
+          assetFileDescriptor.close();
+        }
+      } catch (IOException e) {
+         throw new RawResourceDataSourceException(e);
+      } finally {
+        assetFileDescriptor = null;
+        if (opened) {
+          opened = false;
+          if (listener != null) {
+            listener.onTransferEnd(this);
+          }
+        }
+      }
+    }
+  }
+
+}