android - 如何发现使用 Android 的 Chromecast 设备？

Question

我想查找 Chromecast 设备并调整音量。

Answer 1

1. 获取设备
2. 获取您的 device whitelisted (您需要设备序列号和 HTML5 接收器的 URL)
3. 您将收到两个 APPID(开发/生产)
4. 在您的开发环境中确保更新到 Android 支持库 v18
5. 您将使用 MediaRouter
6. 初始化

import com.google.cast.CastContext;     
Context applicationContext = …; CastContext castContext = new
CastContext(applicationContext);

• 您需要一个MediaRouteButton

< android.support.v7.app.MediaRouteButton
  android:id="@+id/media_route_button"
  android:mediaRouteTypes="user"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:visibility="visible" />

import com.google.cast.CastContext; 
import com.google.cast.CastDevice;
import com.google.cast.MediaRouteAdapter; 
import com.google.cast.MediaRouteHelper; 
import com.google.cast.MediaRouteStateChangeListener;

import android.support.v4.app.FragmentActivity;
import android.support.v7.app.MediaRouteButton;
import android.support.v7.media.MediaRouteSelector;
import android.support.v7.media.MediaRouter;
import android.support.v7.media.MediaRouter.RouteInfo; 

public class MyCastActivity extends FragmentActivity implements MediaRouteAdapter {
     private MediaRouteButton mMediaRouteButton;
     private MediaRouter mMediaRouter;
     private MediaRouteSelector mMediaRouteSelector;
     private MediaRouter.Callback mMediaRouterCallback;
     private CastDevice mSelectedDevice;
     private MediaRouteStateChangeListener mRouteStateListener;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.my_cast_activity);
         mMediaRouteButton = (MediaRouteButton) findViewById(R.id.media_route_button);

• 构造一个CastContext。

mCastContext = new CastContext(getApplicationContext());

- 通过调用注册 MinimalCastMediaRouteProvider MediaRouteHelper.registerMinimalMediaRouteProvider()，传递一个 实现 MediaRouteAdapter 接口(interface)的对象。

MediaRouteHelper.registerMinimalMediaRouteProvider(mCastContext, this);
mMediaRouter = MediaRouter.getInstance(getApplicationContext());

• 通过调用构造一个 MediaRouteSelectorMediaRouteHelper.buildMediaRouteSelector()。有两种形式此方法:第一个不带参数，第二个带参数接收方应用程序名称和/或消息协议(protocol)列表。这个后一种形式用于执行等效于由 SDK 的 ApplicationSupportFilterListener 完成。

mMediaRouteSelector = MediaRouteHelper.buildMediaRouteSelector( MediaRouteHelper.CATEGORY_CAST);

• 将 MediaRouteSelector 分配给 MediaRouteButton。

mMediaRouteButton.setRouteSelector(mMediaRouteSelector);

• 实现一个MediaRouter.Callback并将其添加到MediaRouter，将 CALLBACK_FLAG_REQUEST_DISCOVERY 传递给 MediaRouter 以启动发现。当用户选择或取消选择路线时GUI picker，这个回调接口(interface)对应的方法会被调用。

    mMediaRouterCallback = new MyMediaRouterCallback();
}

@Override
protected void onStart() {
   super.onStart();
    mMediaRouter.addCallback(mMediaRouteSelector, mMediaRouterCallback,
        MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY);
}

@Override
protected void onStop() {
    mMediaRouter.removeCallback(mMediaRouterCallback);
    super.onStop();
}

@Override
protected void onDestroy() {
    MediaRouteHelper.unregisterMediaRouteProvider(mCastContext);
    mCastContext.dispose();
    super.onDestroy();
}

• 在 MediaRouter.Callback 的 onRouteSelected() 回调中，进行调用到 MediaRouteHelper.requestCastDeviceForRoute() 获取一个所选媒体路由的 CastDevice 对象，以及MediaRouteStateChangeListener 需要在任何时候通知路线量或转机状态发生变化。

private class MyMediaRouterCallback extends MediaRouter.Callback {
    @Override
    public void onRouteSelected(MediaRouter router, RouteInfo route) {
        MediaRouteHelper.requestCastDeviceForRoute(route);
    }

    @Override
    public void onRouteUnselected(MediaRouter router, RouteInfo route) {
        mSelectedDevice = null;
        mRouteStateListener = null;
    }
}

// MediaRouteAdapter implementation

@Override
public void onDeviceAvailable(CastDevice device,
        MediaRouteStateChangeListener listener) {
    mSelectedDevice = device;
    mRouteStateListener = listener;
}

@Override
public void onSetVolume(double volume) {
    // Handle volume change.
}

@Override
public void onUpdateVolume(double delta) {
    // Handle volume change.
}

}