在手機與可穿戴設備Wearable通過藍牙Bluetooth傳遞Assets（圖片等）

開發android wear程序時，經常需要將圖片通過Assets 藍牙傳輸。

1.創建asset,使用create...()方法，比如傳遞一個Bitmap傳輸如下

private static Asset createAssetFromBitmap(Bitmap bitmap) {
    final ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, byteStream);
    return Asset.createFromBytes(byteStream.toByteArray());
}

創建了asset，需要將它指向一個data item，通過使用putAsset（） 方法如下

使用PutDataRequest

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.image);
Asset asset = createAssetFromBitmap(bitmap);
PutDataRequest request = PutDataRequest.create("/image");
request.putAsset("profileImage", asset);
Wearable.DataApi.putDataItem(mGoogleApiClient, request);

使用PutDataMapRequest

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.image);
Asset asset = createAssetFromBitmap(bitmap);
PutDataRequest request = PutDataRequest.create("/image");
request.putAsset("profileImage", asset);
Wearable.DataApi.putDataItem(mGoogleApiClient, request);

使用PutDataMapRequest

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.image);
Asset asset = createAssetFromBitmap(bitmap);
PutDataMapRequest dataMap = PutDataMapRequest.create("/image");
dataMap.getDataMap().putAsset("profileImage", asset)
PutDataRequest request = dataMap.asPutDataRequest();
PendingResult<DataApi.DataItemResult> pendingResult = Wearable.DataApi
        .putDataItem(mGoogleApiClient, request);

2. 手錶端接收asset

@Override
public void onDataChanged(DataEventBuffer dataEvents) {
  for (DataEvent event : dataEvents) {
    if (event.getType() == DataEvent.TYPE_CHANGED &&
        event.getDataItem().getUri().getPath().equals("/image")) {
      DataMapItem dataMapItem = DataMapItem.fromDataItem(event.getDataItem());
      Asset profileAsset = dataMapItem.getDataMap().getAsset("profileImage");
      Bitmap bitmap = loadBitmapFromAsset(profileAsset);
      // Do something with the bitmap
    }
  }
}

public Bitmap loadBitmapFromAsset(Asset asset) {
    if (asset == null) {
        throw new IllegalArgumentException("Asset must be non-null");
    }
    ConnectionResult result =
           mGoogleApiClient.blockingConnect(TIMEOUT_MS, TimeUnit.MILLISECONDS);
    if (!result.isSuccess()) {
        return null;
    }
    // convert asset into a file descriptor and block until it's ready
    InputStream assetInputStream = Wearable.DataApi.getFdForAsset(
            mGoogleApiClient, asset).await().getInputStream();
            mGoogleApiClient.disconnect();

    if (assetInputStream == null) {
        Log.w(TAG, "Requested an unknown Asset.");
        return null;
    }
    // decode the stream into a bitmap
    return BitmapFactory.decodeStream(assetInputStream);
}