Java AssetFileDescriptor.getFileDescriptor方法代碼示例

import android.content.res.AssetFileDescriptor; //導入方法依賴的package包/類
public void setDataSource(Context context, Uri uri)
    throws IllegalArgumentException, SecurityException {
    if (uri == null) {
        throw new IllegalArgumentException();
    }
    
    String scheme = uri.getScheme();
    if (SmbProxy.needToStream(scheme)){
        mSmbProxy = SmbProxy.setDataSource(uri, this, null);
        return;
    }
    if(scheme == null || scheme.equals("file")) {
        setDataSource(uri.getPath());
        return;
    }

    AssetFileDescriptor fd = null;
    try {
        ContentResolver resolver = context.getContentResolver();
        try {
            fd = resolver.openAssetFileDescriptor(uri, "r");
        } catch(FileNotFoundException e) {
            throw new IllegalArgumentException();
        }
        if (fd == null) {
            throw new IllegalArgumentException();
        }
        FileDescriptor descriptor = fd.getFileDescriptor();
        if (!descriptor.valid()) {
            throw new IllegalArgumentException();
        }
        // Note: using getDeclaredLength so that our behavior is the same
        // as previous versions when the content provider is returning
        // a full file.
        if (fd.getDeclaredLength() < 0) {
            setDataSource(descriptor);
        } else {
            setDataSource(descriptor, fd.getStartOffset(), fd.getDeclaredLength());
        }
        return;
    } catch (SecurityException ex) {
    } finally {
        try {
            if (fd != null) {
                fd.close();
            }
        } catch(IOException ioEx) {
        }
    }
    setDataSource(uri.toString(), null, null);
}
 

import android.content.res.AssetFileDescriptor; //導入方法依賴的package包/類
@Override
public long open(DataSpec dataSpec) throws ContentDataSourceException {
  try {
    uriString = dataSpec.uri.toString();
    AssetFileDescriptor assetFd = resolver.openAssetFileDescriptor(dataSpec.uri, "r");
    inputStream = new FileInputStream(assetFd.getFileDescriptor());
    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_UNBOUNDED) {
      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_UNBOUNDED;
      }
    }
  } catch (IOException e) {
    throw new ContentDataSourceException(e);
  }

  opened = true;
  if (listener != null) {
    listener.onTransferStart();
  }

  return bytesRemaining;
}
 

import android.content.res.AssetFileDescriptor; //導入方法依賴的package包/類
/**
 * Loads the audio or video specified by mediaPath into the given
 * MediaPlayer.
 *
 * @param mediaPlayer the MediaPlayer
 * @param form the Form
 * @param mediaPath the path to the media
 */
public static void loadMediaPlayer(MediaPlayer mediaPlayer, Form form, String mediaPath)
    throws IOException {
  MediaSource mediaSource = determineMediaSource(form, mediaPath);
  switch (mediaSource) {
    case ASSET:
      AssetFileDescriptor afd = getAssetsIgnoreCaseAfd(form,mediaPath);
      try {
        FileDescriptor fd = afd.getFileDescriptor();
        long offset = afd.getStartOffset();
        long length = afd.getLength();
        mediaPlayer.setDataSource(fd, offset, length);
      } finally {
        afd.close();
      }
      return;


    case REPL_ASSET:
      mediaPlayer.setDataSource(replAssetPath(mediaPath));
      return;

    case SDCARD:
      mediaPlayer.setDataSource(mediaPath);
      return;

    case FILE_URL:
      mediaPlayer.setDataSource(fileUrlToFilePath(mediaPath));
      return;

    case URL:
      // This works both for streaming and non-streaming.
      // TODO(halabelson): Think about whether we could get improved
      // performance if we did buffering control.
      mediaPlayer.setDataSource(mediaPath);
      return;

    case CONTENT_URI:
      mediaPlayer.setDataSource(form, Uri.parse(mediaPath));
      return;

    case CONTACT_URI:
      throw new IOException("Unable to load audio or video for contact " + mediaPath + ".");
  }
  throw new IOException("Unable to load audio or video " + mediaPath + ".");
}