android - 无法连接 MediaBrowserCompat

Question

我关注了 Android official documentation on connecting MediaBrowserCompat但它拒绝连接，事实上 onConnected()、onConnectionSuspended() 或 onConnectionFailed() 都没有被调用。

我也试过this answer但它没有用。

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_audio_player);
        ButterKnife.bind(this);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        setupMediaComponents();


       // initializeViews();
    }

private void setupMediaComponents() {
        Log.d(TAG, "setupMediaComponents");
        setVolumeControlStream(AudioManager.STREAM_MUSIC);

        mediaBrowserCompat = new MediaBrowserCompat(this, new ComponentName(this, SongPlayerService.class),
                mediaBrowserCompatConnectionCallback, null);
    }

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

    @Override
    public void onStop() {
        super.onStop();
        // (see "stay in sync with the MediaSession")
        if (MediaControllerCompat.getMediaController(this) != null) {


    MediaControllerCompat.getMediaController(this).unregisterCallback(controllerCallback);
            }
            mediaBrowserCompat.disconnect();

        }

private MediaBrowserCompat.ConnectionCallback mediaBrowserCompatConnectionCallback = new MediaBrowserCompat.ConnectionCallback() {
        @Override
        public void onConnected() {
            Log.d(TAG, "onConnected");
            try {
                // Create a MediaControllerCompat
                MediaControllerCompat mediaController =
                        new MediaControllerCompat(AudioPlayerActivity.this,  mediaBrowserCompat.getSessionToken());

                // Save the controller
                MediaControllerCompat.setMediaController(AudioPlayerActivity.this, mediaController);

                setControlClickListeners();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onConnectionSuspended() {
            Log.d(TAG, "onConnectionSuspended");
            // We were connected, but no longer :-(
        }

        @Override
        public void onConnectionFailed() {
            Log.d(TAG, "onConnectionFailed");
            // The attempt to connect failed completely.
            // Check the ComponentName!
        }
    };

我正在使用版本 25.3.1 的支持库，所有 sdk 工具都是最新的。

---

编辑

SongPlayerService的一部分

@Nullable
    @Override
    public BrowserRoot onGetRoot(@NonNull String clientPackageName, int clientUid, @Nullable Bundle rootHints) {
        // Returning null means no one can connect so we’ll return something
        return new BrowserRoot(getString(R.string.app_name), null); // Name visible in Android auto, Bundle is for optional params
        // TODO: Support Android auto
    }

Answer 1

终于找到问题的根源了。我覆盖了 onBind 并返回了 null。

@Nullable
@Override
public IBinder onBind(Intent intent) {
    return null;
}

删除上面的行为我修复了它。