Activity与Service通信（不同进程之间）

1.public class MessengerService extends Service {  
2.    /** 用于Handler里的消息类型 */  
3.    static final int MSG_SAY_HELLO = 1;  
4.  
5.    /** 
6.     * 在Service处理Activity传过来消息的Handler 
7.     */  
8.    class IncomingHandler extends Handler {  
9.        @Override  
10.        public void handleMessage(Message msg) {  
11.            switch (msg.what) {  
12.                case MSG_SAY_HELLO:  
13.                    Toast.makeText(getApplicationContext(), "hello!", Toast.LENGTH_SHORT).show();  
14.                    break;  
15.                default:  
16.                    super.handleMessage(msg);  
17.            }  
18.        }  
19.    }  
20.  
21.    /** 
22.     * 这个Messenger可以关联到Service里的Handler，Activity用这个对象发送Message给Service，Service通过Handler进行处理。 
23.     */  
24.    final Messenger mMessenger = new Messenger(new IncomingHandler());  
25.  
26.    /** 
27.     * 当Activity绑定Service的时候，通过这个方法返回一个IBinder，Activity用这个IBinder创建出的Messenger，就可以与Service的Handler进行通信了 
28.     */  
29.    @Override  
30.    public IBinder onBind(Intent intent) {  
31.        Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT).show();  
32.        return mMessenger.getBinder();  
33.    }  
34.}  

1.public class ActivityMessenger extends Activity {  
2.    /** 向Service发送Message的Messenger对象 */  
3.    Messenger mService = null;  
4.  
5.    /** 判断有没有绑定Service */  
6.    boolean mBound;  
7.  
8.    private ServiceConnection mConnection = new ServiceConnection() {  
9.        public void onServiceConnected(ComponentName className, IBinder service) {  
10.            // Activity已经绑定了Service  
11.            // 通过参数service来创建Messenger对象，这个对象可以向Service发送Message，与Service进行通信  
12.            mService = new Messenger(service);  
13.            mBound = true;  
14.        }  
15.  
16.        public void onServiceDisconnected(ComponentName className) {  
17.            mService = null;  
18.            mBound = false;  
19.        }  
20.    };  
21.  
22.    public void sayHello(View v) {  
23.        if (!mBound) return;  
24.        // 向Service发送一个Message  
25.        Message msg = Message.obtain(null, MessengerService.MSG_SAY_HELLO, 0, 0);  
26.        try {  
27.            mService.send(msg);  
28.        } catch (RemoteException e) {  
29.            e.printStackTrace();  
30.        }  
31.    }  
32.  
33.    @Override  
34.    protected void onCreate(Bundle savedInstanceState) {  
35.        super.onCreate(savedInstanceState);  
36.        setContentView(R.layout.main);  
37.    }  
38.  
39.    @Override  
40.    protected void onStart() {  
41.        super.onStart();  
42.        // 绑定Service  
43.        bindService(new Intent(this, MessengerService.class), mConnection,  
44.            Context.BIND_AUTO_CREATE);  
45.    }  
46.  
47.    @Override  
48.    protected void onStop() {  
49.        super.onStop();  
50.        // 解绑  
51.        if (mBound) {  
52.            unbindService(mConnection);  
53.            mBound = false;  
54.        }  
55.    }  
56.}