在手机与可穿戴设备Wearable通过蓝牙Bluetooth传递Assets（图片等）

开发android wear程序时，经常需要将图片通过Assets 蓝牙传输。

1.创建asset,使用create...()方法，比如传递一个Bitmap传输如下

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

创建了asset，需要将它指向一个data item，通过使用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. 手表端接收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);
 }