Question

我试图通过遵循Android开发人员培训来转移资产，该培训说使用此代码：

@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);
}

所以我以大致相同的方式做了同样的事情：

    // Build a new GoogleApiClient for the Wearable API
    googleClient = new GoogleApiClient.Builder(this)
            .addConnectionCallbacks(new GoogleApiClient.ConnectionCallbacks() {
                @Override
                public void onConnected(Bundle bundle) {
                    Wearable.DataApi.addListener(googleClient, onDataChangedListener);
                }

                @Override
                public void onConnectionSuspended(int i) {

                }
            })
            .addApi(Wearable.API)
            .build();
    googleClient.connect();

在我的onDatachanged方法中我有：

public DataApi.DataListener onDataChangedListener = new DataApi.DataListener() {
    @Override
    public void onDataChanged(DataEventBuffer dataEvents) {
        Log.d(TAG, "Data changed: " + dataEvents);

        for (DataEvent event : dataEvents) {
            Log.d(TAG, "Data received: " + event.getDataItem().getUri());

            if (event.getType() == DataEvent.TYPE_CHANGED &&
                event.getDataItem().getUri().getPath().equals("/audio")) {
                DataMapItem dataMapItem = DataMapItem.fromDataItem(event.getDataItem());
                Asset audioAsset = dataMapItem.getDataMap().getAsset("audioAsset");
                audioBytes = loadBytesFromAsset(audioAsset);
            }

            // Set play button enabled
            handler.post(onNewAudio());
        }
    }
}

使用我的loadBytesFromAsset（）方法：

public byte[] loadBytesFromAsset(Asset asset) {
    if (asset == null) {
        throw new IllegalArgumentException("Asset must be non-null");
    }

    result = googleClient.blockingConnect(3000, TimeUnit.MILLISECONDS);
    if(!result.isSuccess()){
        return null;
    }

    // Convert asset into a file descriptor and block until it's ready
    InputStream assetInputStream = Wearable.DataApi.getFdForAsset(googleClient, asset).await().getInputStream();
    googleClient.disconnect();

    if (assetInputStream == null) {
        Log.w(TAG, "Requested an unknown Asset.");
        return null;
    }
    // Decode the stream into a byte[]
    return getBytesFromInputStream(assetInputStream);
}

这似乎与Android开发人员培训建议完全一样，但是当我运行它时，＆＃39; loadBytesFromAsset（）＆＃39;方法崩溃，但有一个例外，即我无法在UI线程上调用blockingConnect（）。有谁知道如何解决这个问题？我该如何倾听并检索资产？提前谢谢。

Answer 1

好吧，我让它工作（有点），仍然遇到onDataChanged未被调用的问题，但是通过重新执行像这篇文章{{3}这样的代码来解决UI线程和blocking.connect调用的问题}。他们这样做的方法是让类实现DataApi.DataListener，GoogleApiClient.ConnectionCallbacks和GoogleApiClient.OnConnectionFailedListener接口，如下所示：

public class MainActivity extends Activity implements
        DataApi.DataListener, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener{
    private TextView mTextView;
    private static final long CONNECTION_TIME_OUT_MS = 100;
    private static final String ON_MESSAGE = "On!";
    private static final String OFF_MESSAGE = "Off!";
    private static final String TAG = "Moto360DisplayControl";
    private GoogleApiClient client;
    private String nodeId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initApi();
    }

    private void initApi() {
        client = getGoogleApiClient(this);
        retrieveDeviceNode();
    }

    private GoogleApiClient getGoogleApiClient(Context context) {
        return new GoogleApiClient.Builder(context)
            .addApi(Wearable.API)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .build();
    }

    private void retrieveDeviceNode() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                client.blockingConnect(CONNECTION_TIME_OUT_MS, TimeUnit.MILLISECONDS);
                NodeApi.GetConnectedNodesResult result =
                    Wearable.NodeApi.getConnectedNodes(client).await();
                List<Node> nodes = result.getNodes();
                if (nodes.size() > 0) {
                    nodeId = nodes.get(0).getId();
                }
                client.disconnect();
            }
        }).start();
    }

    @Override
    protected void onStart() {
        super.onStart();
        client.connect();
    }

    @Override
    public void onConnected(Bundle connectionHint) {
        Wearable.DataApi.addListener(client, this);
        Toast.makeText(this, "AddedListener!", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onConnectionSuspended(int num) {
        Toast.makeText(this, "ConnectionSuspended", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onConnectionFailed(ConnectionResult res) {
        Toast.makeText(this, "ConnectionFailed", Toast.LENGTH_LONG).show();
    }

    @Override
    protected void onStop() {
        Wearable.DataApi.removeListener(client, this);
        client.disconnect();
        super.onStop();
    }

    @Override
    public void onDataChanged(DataEventBuffer dataEvents) {
        Toast.makeText(this, "DataChanged!", Toast.LENGTH_LONG).show();
        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 bitmap
                Toast.makeText(this, "DataChanged!", Toast.LENGTH_LONG).show();
            }
        }
    }

    public Bitmap loadBitmapFromAsset(Asset asset) {
        if (asset == null) {
            throw new IllegalArgumentException("Asset must be non-null");
        }

        ConnectionResult result = client.blockingConnect(CONNECTION_TIME_OUT_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(client, asset).await().getInputStream();
        client.disconnect();

        if (assetInputStream == null) {
            Log.w(TAG, "Requested an unknown Asset.");
            return null;
        }

        // Decode the stream into a bitmap
        return BitmapFactory.decodeStream(assetInputStream);
    }
}

使用这种方法，问题解决了，我仍然在努力解决onDataChanged未被调用的问题，我已经问过here。

Answer 2

（免责声明：我从未真正测试过这个答案，但只是通过API阅读）

请参阅此内容 - https://developers.google.com/android/reference/com/google/android/gms/common/api/GoogleApiClient

您可以看到connectBlocking旁边还有connect。文档说

将客户端连接到Google Play服务。此方法返回立即，并在后台连接到服务。如果连接成功，onConnected（Bundle）被调用并入队项目被执行。失败时，onConnectionFailed（ConnectionResult）被称为。

所以你需要做的就是致电registerConnectionCallbacks并传递ConnectionCallbacks来实现onConnected。这些回调将在UI线程中运行（就像当前的回调在那里运行一样）。此外，您还可以对isConnectionFailedListenerRegistered执行相同操作，这将在连接失败时调用。这实际上就是你在代码的第一段中所做的事情，只是你在构建器中设置了监听器。

这需要对代码进行一些更改，但我认为没有太严肃的事情。

Answer 3

鉴于您拥有的代码结构，在我看来，您正在onConnected（）回调中注册onDataChangedListener（这是正确的位置）。在onDataChangedListener＃onDataChanged（）回调（在主线程上调用）中，您正在调用loadBytesFromAsset（）。在此方法中，您无需再次连接google api客户端;它应该已经在那时连接，因此不需要调用阻塞连接方法。检查以确保连接（apiClient.isConnected（））然后继续执行您想要执行的操作是一种很好的做法。

除非您确定不想在应用中执行任何其他需要连接;最好只调用活动的onStop（）中的断开连接（并在onStart（）中建立连接）。

那就是说，如果你需要在那些回调中进行的任何进程（在主线程上）是一个很长的进程，那么你需要生成一个单独的线程（比如，使用AsyncTask，IntentService或者某个（那种）并处理那里的漫长过程。

如何在不阻止UI线程的情况下传输Android资产？

3 个答案: