How do I discover a Chromecast device using Androi

问题:

I'd like to discover a Chromecast device and adjust the volume.

回答1:

1. Get a device
2. Get your device whitelisted (you'll need the device serial #, and a URL for your HTML5 receiver)
3. You'll be sent two APPID (development / production)
4. In your development environment make sure to update to Android Support Library v18
5. You'll be using MediaRouter
6. Initialize

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

• You'll need a 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);

• Construct a CastContext.

mCastContext = new CastContext(getApplicationContext());

- Register the MinimalCastMediaRouteProvider by calling MediaRouteHelper.registerMinimalMediaRouteProvider(), passing an object that implements the MediaRouteAdapter interface.

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

• Construct a MediaRouteSelector by calling MediaRouteHelper.buildMediaRouteSelector(). There are two forms of this method: the first takes no parameters and the second takes a receiver application name and/or a list of message protocols. This latter form is used to perform device filtering equivalent to that done by the SDK’s ApplicationSupportFilterListener.

mMediaRouteSelector = MediaRouteHelper.buildMediaRouteSelector( MediaRouteHelper.CATEGORY_CAST);

• Assign the MediaRouteSelector to the MediaRouteButton.

mMediaRouteButton.setRouteSelector(mMediaRouteSelector);

• Implement a MediaRouter.Callback and add it to the MediaRouter, passing CALLBACK_FLAG_REQUEST_DISCOVERY to the MediaRouter to initiate discovery. When the user selects or deselects a route in the GUI picker, the corresponding method on this callback interface will be invoked.

    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();
}

• In the MediaRouter.Callback’s onRouteSelected() callback, make a call to MediaRouteHelper.requestCastDeviceForRoute() to obtain a CastDevice object for the selected media route, as well as the MediaRouteStateChangeListener that will need to be notified whenever route volume or connecting state changes.

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.
}

}