接前三篇 基础篇 Bundle篇 文件共享篇
Messenger即信使，我们可以通过它在进程间传递我们的数据，本篇我们来用Messenger实现进程间通信 服务端 1）首先在服务端定义一个Service服务，用这个Service来处理客户端的请求 2）其次需要通过一个Handler来创建一个Messenger对象，并在Service的onBind方法中返回这个Messenger 3）在Messenger的handleMessage中通过形参Message携带的messenger对象将处理结果发送给客户端
public class MessengerService extends Service { public static final String TAG = "myMessagePractise"; public static final int MSG_FROM_CLIENT = 1; public static final int MSG_FROM_SERVER = 2; public static class MessengerHandler extends Handler{ @Override public void handleMessage(Message msg){ switch (msg.what){ case MSG_FROM_CLIENT: Log.d(TAG,"server receive message, content is \" " + msg.getData().getString("replay") + " \" "); Message sMsg = Message.obtain(null,MSG_FROM_SERVER); Bundle bundle = new Bundle(); bundle.putString("replay","hello, this is server! "); sMsg.setData(bundle); Messenger messenger = msg.replyTo; try { messenger.send(sMsg); } catch (RemoteException e) { e.printStackTrace(); } break; default: super.handleMessage(msg); } } } private final Messenger mMessenger = new Messenger(new MessengerHandler()); @Nullable @Override public IBinder onBind(Intent intent) { return mMessenger.getBinder(); } }客户端 1）我们用一个Activity作为客户端，通过绑定一个ServiceConnection获得服务端的Messenger，并通过这个Messenger项服务端发送消息 2）同时也通过一个Handler来创建Messenger对象 3）最后在给服务端发消息时，将我们客户端的Messenger装载在Mesage中（这里就与服务端的3）相对应）
public class MessengerActivity extends Activity { public static final String TAG = "myMessagePractise"; private Messenger messenger; private ServiceConnection connection = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { messenger = new Messenger(service); Message msg = Message.obtain(null, MessengerService.MSG_FROM_CLIENT); Bundle bundle = new Bundle(); bundle.putString("replay","hello, this is client"); msg.setData(bundle); msg.replyTo = messengerHandler; try{ messenger.send(msg); }catch (RemoteException e){ e.printStackTrace(); } } @Override public void onServiceDisconnected(ComponentName name) { } }; private Messenger messengerHandler = new Messenger(new MessengerHandler()); private static class MessengerHandler extends Handler{ @Override public void handleMessage(Message msg){ switch (msg.what){ case MessengerService.MSG_FROM_SERVER: Log.d(TAG,"client receive message, content is \" " + msg.getData().getString("replay") + " \" "); } } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Intent intent = new Intent(this, MessengerService.class); bindService(intent,connection, Context.BIND_AUTO_CREATE); } @Override protected void onDestroy(){ unbindService(connection); super.onDestroy(); } }Manifest文件 我们需要在Manifest文件中将Service和Activity置于不同的进程中
<activity android:name=".MessengerActivity" android:process="com.practise.ipc.client"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <service android:name="com.practise.ipc.ipcmessenger.MessengerService" android:process="com.practise.ipc.server"/>运行结果 运行结果是预期的，说明我们利用Messengerr完成了进程间的通信 下一篇 AIDL实现进程间通信
特别感谢《Android 开发艺术探索》
