android.content.res.AssetFileDescriptor#getLength()源码实例Demo

public static void findAPKFile(String filepath, Context context) {
    String apkFilepath = getAPKFilepath(context);

    // Get the offset and length for the file: theUrl, that is in your
    // assets folder
    AssetManager assetManager = context.getAssets();
    try {

        AssetFileDescriptor assFD = assetManager.openFd(filepath);
        if (assFD != null) {
            long offset = assFD.getStartOffset();
            long fileSize = assFD.getLength();





            assFD.close();

            // **** offset and fileSize are the offset and size
            // **** in bytes of the asset inside the APK
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}
 

@Override
public long getLength(Context context) throws PayloadNotFoundException {
    AssetFileDescriptor afd = null;
    long size = 0;
    try {
        afd = context.getResources().openRawResourceFd(data);
        size = afd.getLength();
    } catch (Resources.NotFoundException e) {
        throw new ResourceNotFoundException(String.format("Resource id %d not found", data));
    } finally {
        if (afd != null) {
            try {
                afd.close();
            } catch (IOException ignored) {
            }
        }
    }

    return size;
}
 

protected static long getAssetFileSize(String filename) {
    AssetFileDescriptor assetFileDescriptor = null;
    try {
        assetFileDescriptor = InstrumentationRegistry.getInstrumentation().getContext().getAssets().openFd(filename);
        return assetFileDescriptor.getLength();
    } catch (IOException e) {
        return -1;
    } finally {
        if (assetFileDescriptor != null) {
            try {
                assetFileDescriptor.close();
            } catch (IOException ignored) {
            }
        }
    }
}
 

@Override
protected int getLength(ImageRequest imageRequest) {
  AssetFileDescriptor fd = null;
  try {
    fd = mResources.openRawResourceFd(getResourceId(imageRequest));
    return (int) fd.getLength();
  } catch (Resources.NotFoundException e) {
    return -1;
  } finally {
    try {
      if (fd != null) {
        fd.close();
      }
    } catch (IOException ignored) {
      // There's nothing we can do with the exception when closing descriptor.
    }
  }
}
 

/**
 * {@inheritDoc}
 */
@Override
public long getLength(Uri uri) {
  AssetFileDescriptor afd;
  long result=super.getLength(uri);

  try {
    afd=getAssetFileDescriptor(uri);
    result=afd.getLength();
    afd.close();
  }
  catch (Exception e) {
    Log.w(getClass().getSimpleName(), "Exception getting asset length", e);
  }

  return(result);
}
 

private int getLength(ImageRequest imageRequest) {
  AssetFileDescriptor fd = null;
  try {
    fd = mResources.openRawResourceFd(getResourceId(imageRequest));
    return (int) fd.getLength();
  } catch (Resources.NotFoundException e) {
    return -1;
  } finally {
    try {
      if (fd != null) {
        fd.close();
      }
    } catch (IOException ignored) {
      // There's nothing we can do with the exception when closing descriptor.
    }
  }
}
 

private int getLength(ImageRequest imageRequest) {
  AssetFileDescriptor fd = null;
  try {
    fd = mAssetManager.openFd(getAssetName(imageRequest));
    return (int) fd.getLength();
  } catch (IOException e) {
    return -1;
  } finally {
    try {
      if (fd != null) {
        fd.close();
      }
    } catch (IOException ignored) {
      // There's nothing we can do with the exception when closing descriptor.
    }
  }
}
 

private static AudioBuffer loadBuffer(AssetInfo assetInfo) throws IOException {
    AndroidAssetInfo aai = (AndroidAssetInfo) assetInfo;
    AssetFileDescriptor afd = null;
    NativeVorbisFile file = null;
    try {
        afd = aai.openFileDescriptor();
        int fd = afd.getParcelFileDescriptor().getFd();
        file = new NativeVorbisFile(fd, afd.getStartOffset(), afd.getLength());
        ByteBuffer data = BufferUtils.createByteBuffer(file.totalBytes);
        file.readFully(data);
        AudioBuffer ab = new AudioBuffer();
        ab.setupFormat(file.channels, 16, file.sampleRate);
        ab.updateData(data);
        return ab;
    } finally {
        if (file != null) {
            file.close();
        }
        if (afd != null) {
            afd.close();
        }
    }
}
 

public static void copy(ContentResolver resolver, Uri source, Uri dest, OnCopyListener listener) throws IOException {

        FileInputStream in = null;
        OutputStream out = null;
        try{
            AssetFileDescriptor fd = resolver.openAssetFileDescriptor(source, "r");
            in =  fd != null ? fd.createInputStream() : null;

            if (in == null){
                throw new IOException("open the src file failed");
            }
            long total = fd.getLength();
            long sum = 0;

            out = resolver.openOutputStream(dest);

            if (out == null) {
                throw new IOException("open the dest file failed");
            }
            // Transfer bytes from in to out
            byte[] buf = new byte[1024 * 4];
            int len;
            Thread thread = Thread.currentThread();
            while ((len = in.read(buf)) > 0) {
                if (thread.isInterrupted()) {
                    break;
                }
                sum += len;
                out.write(buf, 0, len);
                if (listener != null) {
                    listener.inProgress(sum * 1.0f / total);
                }
            }
        }finally {
            IOUtil.closeQuiet(in);
            IOUtil.closeQuiet(out);
        }
    }
 

@Override public Result load(Request request, int networkPolicy) throws IOException {
  String imagePath = request.uri.getPath().substring(1); // Grab only the path sans leading slash.

  // Check the disk cache for the image. A non-null return value indicates a hit.
  boolean cacheHit = emulatedDiskCache.get(imagePath) != null;

  // If there's a hit, grab the image stream and return it.
  if (cacheHit) {
    return new Result(loadBitmap(imagePath), Picasso.LoadedFrom.DISK);
  }

  // If we are not allowed to hit the network and the cache missed return a big fat nothing.
  if (NetworkPolicy.isOfflineOnly(networkPolicy)) {
    return null;
  }

  // If we got this far there was a cache miss and hitting the network is required. See if we need
  // to fake an network error.
  if (behavior.calculateIsFailure()) {
    SystemClock.sleep(behavior.calculateDelay(MILLISECONDS));
    throw new IOException("Fake network error!");
  }

  // We aren't throwing a network error so fake a round trip delay.
  SystemClock.sleep(behavior.calculateDelay(MILLISECONDS));

  // Since we cache missed put it in the LRU.
  AssetFileDescriptor fileDescriptor = assetManager.openFd(imagePath);
  long size = fileDescriptor.getLength();
  fileDescriptor.close();

  emulatedDiskCache.put(imagePath, size);

  // Grab the image stream and return it.
  return new Result(loadBitmap(imagePath), Picasso.LoadedFrom.NETWORK);
}
 

@Override
public long getLength() throws IOException {
    if (length >= 0) {
        return length;
    }

    AssetFileDescriptor fileDescriptor = null;
    try {
        fileDescriptor = context.getResources().openRawResourceFd(drawableId);
        length = fileDescriptor != null ? fileDescriptor.getLength() : 0;
    } finally {
        SketchUtils.close(fileDescriptor);
    }
    return length;
}
 

@CalledByNative
public static long[] open(String fileName) {
    AssetFileDescriptor afd = null;
    try {
        AssetManager manager = ContextUtils.getApplicationContext().getAssets();
        afd = manager.openNonAssetFd(fileName);
        return new long[] {afd.getParcelFileDescriptor().detachFd(), afd.getStartOffset(),
                afd.getLength()};
    } catch (IOException e) {
        // As a general rule there's no point logging here because the caller should handle
        // receiving an fd of -1 sensibly, and the log message is either mirrored later, or
        // unwanted (in the case where a missing file is expected), or wanted but will be
        // ignored, as most non-fatal logs are.
        // It makes sense to log here when the file exists, but is unable to be opened as an fd
        // because (for example) it is unexpectedly compressed in an apk. In that case, the log
        // message might save someone some time working out what has gone wrong.
        // For that reason, we only suppress the message when the exception message doesn't look
        // informative (Android framework passes the filename as the message on actual file not
        // found, and the empty string also wouldn't give any useful information for debugging).
        if (!e.getMessage().equals("") && !e.getMessage().equals(fileName)) {
            Log.e(LOGTAG, "Error while loading asset " + fileName + ": " + e);
        }
        return new long[] {-1, -1, -1};
    } finally {
        try {
            if (afd != null) {
                afd.close();
            }
        } catch (IOException e2) {
            Log.e(LOGTAG, "Unable to close AssetFileDescriptor", e2);
        }
    }
}
 

@CalledByNative
public static long[] open(String fileName) {
    AssetFileDescriptor afd = null;
    try {
        AssetManager manager = ContextUtils.getApplicationContext().getAssets();
        afd = manager.openNonAssetFd(fileName);
        return new long[] {afd.getParcelFileDescriptor().detachFd(), afd.getStartOffset(),
                afd.getLength()};
    } catch (IOException e) {
        // As a general rule there's no point logging here because the caller should handle
        // receiving an fd of -1 sensibly, and the log message is either mirrored later, or
        // unwanted (in the case where a missing file is expected), or wanted but will be
        // ignored, as most non-fatal logs are.
        // It makes sense to log here when the file exists, but is unable to be opened as an fd
        // because (for example) it is unexpectedly compressed in an apk. In that case, the log
        // message might save someone some time working out what has gone wrong.
        // For that reason, we only suppress the message when the exception message doesn't look
        // informative (Android framework passes the filename as the message on actual file not
        // found, and the empty string also wouldn't give any useful information for debugging).
        if (!e.getMessage().equals("") && !e.getMessage().equals(fileName)) {
            Log.e(LOGTAG, "Error while loading asset " + fileName + ": " + e);
        }
        return new long[] {-1, -1, -1};
    } finally {
        try {
            if (afd != null) {
                afd.close();
            }
        } catch (IOException e2) {
            Log.e(LOGTAG, "Unable to close AssetFileDescriptor", e2);
        }
    }
}
 

/**
 * Creates drawable from AssetFileDescriptor.
 * Convenience wrapper for {@link GifDrawable#GifDrawable(FileDescriptor)}
 *
 * @param afd source
 * @throws NullPointerException if afd is null
 * @throws IOException          when opening failed
 */
public GifDrawable(AssetFileDescriptor afd) throws IOException {
    if (afd == null)
        throw new NullPointerException("Source is null");
    FileDescriptor fd = afd.getFileDescriptor();
    try {
        mGifInfoPtr = openFd(mMetaData, fd, afd.getStartOffset(), false);
    } catch (IOException ex) {
        afd.close();
        throw ex;
    }
    mColors = new int[mMetaData[0] * mMetaData[1]];
    mInputSourceLength = afd.getLength();
}
 

@Override
public synchronized long getLength() throws IOException {
    if (length >= 0) {
        return length;
    }

    AssetFileDescriptor fileDescriptor = null;
    try {
        fileDescriptor = context.getAssets().openFd(assetsFilePath);
        length = fileDescriptor.getLength();
    } finally {
        SketchUtils.close(fileDescriptor);
    }
    return length;
}
 

@Override public Result load(Request request, int networkPolicy) throws IOException {
    String imagePath = request.uri.getPath().substring(1); // Grab only the path sans leading slash.

    // Check the disk cache for the image. A non-null return value indicates a hit.
    boolean cacheHit = emulatedDiskCache.get(imagePath) != null;

    // If there's a hit, grab the image stream and return it.
    if (cacheHit) {
        return new Result(loadBitmap(imagePath), Picasso.LoadedFrom.DISK);
    }

    // If we are not allowed to hit the network and the cache missed return a big fat nothing.
    if (NetworkPolicy.isOfflineOnly(networkPolicy)) {
        return null;
    }

    // If we got this far there was a cache miss and hitting the network is required. See if we need
    // to fake an network error.
    if (behavior.calculateIsFailure()) {
        SystemClock.sleep(behavior.calculateDelay(MILLISECONDS));
        throw new IOException("Fake network error!");
    }

    // We aren't throwing a network error so fake a round trip delay.
    SystemClock.sleep(behavior.calculateDelay(MILLISECONDS));

    // Since we cache missed put it in the LRU.
    AssetFileDescriptor fileDescriptor = assetManager.openFd(imagePath);
    long size = fileDescriptor.getLength();
    fileDescriptor.close();
    emulatedDiskCache.put(imagePath, size);

    // Grab the image stream and return it.
    return new Result(loadBitmap(imagePath), Picasso.LoadedFrom.NETWORK);
}
 

@Override
public synchronized long getLength() throws IOException {
    if (length >= 0) {
        return length;
    }

    AssetFileDescriptor fileDescriptor = null;
    try {
        fileDescriptor = context.getContentResolver().openAssetFileDescriptor(contentUri, "r");
        length = fileDescriptor != null ? fileDescriptor.getLength() : 0;
    } finally {
        SketchUtils.close(fileDescriptor);
    }
    return length;
}
 

@Override
public long open(DataSpec dataSpec) throws ContentDataSourceException {
  try {
    Uri uri = dataSpec.uri;
    this.uri = uri;

    transferInitializing(dataSpec);
    AssetFileDescriptor assetFileDescriptor = resolver.openAssetFileDescriptor(uri, "r");
    this.assetFileDescriptor = assetFileDescriptor;
    if (assetFileDescriptor == null) {
      throw new FileNotFoundException("Could not open file descriptor for: " + uri);
    }
    FileInputStream inputStream = new FileInputStream(assetFileDescriptor.getFileDescriptor());
    this.inputStream = inputStream;

    long assetStartOffset = assetFileDescriptor.getStartOffset();
    long skipped = inputStream.skip(assetStartOffset + dataSpec.position) - assetStartOffset;
    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 {
      long assetFileDescriptorLength = assetFileDescriptor.getLength();
      if (assetFileDescriptorLength == AssetFileDescriptor.UNKNOWN_LENGTH) {
        // The asset must extend to the end of the file. If FileInputStream.getChannel().size()
        // returns 0 then the remaining length cannot be determined.
        FileChannel channel = inputStream.getChannel();
        long channelSize = channel.size();
        bytesRemaining = channelSize == 0 ? C.LENGTH_UNSET : channelSize - channel.position();
      } else {
        bytesRemaining = assetFileDescriptorLength - skipped;
      }
    }
  } catch (IOException e) {
    throw new ContentDataSourceException(e);
  }

  opened = true;
  transferStarted(dataSpec);

  return bytesRemaining;
}
 

public void readFile(Uri inputFile)
        throws java.io.FileNotFoundException,
        java.io.IOException {
    super.readFile(inputFile);
    mNumFrames = 0;
    mMaxFrames = 64;  // This will grow as needed
    mFrameGains = new int[mMaxFrames];
    mMinGain = 1000000000;
    mMaxGain = 0;
    mBitRate = 10;
    mOffset = 0;

    InputStream stream = null;
    AssetFileDescriptor file;
    file = App.getInstance().getContentResolver().openAssetFileDescriptor(inputFile, "r");

    if(file == null) throw  new NullPointerException("File is null");

    stream = file.createInputStream();
    if(stream == null) throw new NullPointerException("Input stream is null");

    else Log.d("audioSeekbar", "ReadFile: input stream is not null");

    // No need to handle filesizes larger than can fit in a 32-bit int
    mFileSize = (int) file.getLength();

    if (mFileSize < 128) {
        throw new java.io.IOException("File too small to parse");
    }

    byte[] header = new byte[12];
    stream.read(header, 0, 6);
    mOffset += 6;
    if (header[0] == '#' &&
            header[1] == '!' &&
            header[2] == 'A' &&
            header[3] == 'M' &&
            header[4] == 'R' &&
            header[5] == '\n') {
        parseAMR(stream, mFileSize - 6);
    }

    stream.read(header, 6, 6);
    mOffset += 6;

    if (header[4] == 'f' &&
            header[5] == 't' &&
            header[6] == 'y' &&
            header[7] == 'p' &&
            header[8] == '3' &&
            header[9] == 'g' &&
            header[10] == 'p' &&
            header[11] == '4') {

        int boxLen =
                ((0xff & header[0]) << 24) |
                        ((0xff & header[1]) << 16) |
                        ((0xff & header[2]) << 8) |
                        ((0xff & header[3]));

        if (boxLen >= 4 && boxLen <= mFileSize - 8) {
            stream.skip(boxLen - 12);
            mOffset += boxLen - 12;
        }

        parse3gpp(stream, mFileSize - boxLen);
    }
}
 

/**
 * 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:
      form.assertPermission(Manifest.permission.READ_EXTERNAL_STORAGE);
      mediaPlayer.setDataSource(replAssetPath(mediaPath));
      return;

    case SDCARD:
      form.assertPermission(Manifest.permission.READ_EXTERNAL_STORAGE);
      mediaPlayer.setDataSource(mediaPath);
      return;

    case FILE_URL:
      if (isExternalFileUrl(mediaPath)) {
        form.assertPermission(Manifest.permission.READ_EXTERNAL_STORAGE);
      }
      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 + ".");
}