Messenger可以翻译为“信使”,顾名思义,通过它可以再不同进程间传递数据。Mesenger其实是一种轻量级的IPC,它的底层实现就是AIDL。从构造函数就可以看出来
public Messenger(Handler target) {
mTarget = target.getIMessenger();
}
public Messenger(IBinder target) {
mTarget = IMessenger.Stub.asInterface(target);
}
使用方法
创建一个Service处理连接请求,同时创建一个Handler来创建一个Messenger对象,然后在onBind返回这个Binder
public class MessengerService extends Service {
@Override
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
private static class MessengerHandler extends Handler {
@Override
public void handleMessage(Message msg) {
if (msg.what == 0x001) {
Log.i("server", msg.getData().getString("msg"));
// 回复消息给客户端
Messenger client = msg.replyTo;
Message replayMessage = Message.obtain(null, 0x002);
Bundle bundle = new Bundle();
bundle.putString("reply", "消息收到");
replayMessage.setData(bundle);
try {
client.send(replayMessage);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
}
private Messenger mMessenger = new Messenger(new MessengerHandler());
}
首先要绑定Service,绑定成功后用返回的IBinder对象创建一个Messenger,通过这个Messenger就可以向服务端发送消息了。如果需要服务端能够回应客户端,我们还需要创建一个Handler并新创建一个Messenger,并把这个Messenger对象通过Message的replyTo函数传给服务端
public class MainActivity extends Activity {
private Messenger mService;
@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);
}
private ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
mService = new Messenger(service);
Message message = Message.obtain(null, 0x001);
Bundle date = new Bundle();
date.putString("msg", "hello, this is client");
message.setData(date);
// 注意
message.replyTo = mGetMessenger;
try {
mService.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
};
protected void onDestroy() {
unbindService(connection);
super.onDestroy();
};
// 下面是客户端接收消息
private Messenger mGetMessenger = new Messenger(new MessengerGetHandler());
private static class MessengerGetHandler extends Handler {
@Override
public void handleMessage(Message msg) {
if (msg.what == 0x002) {
Log.i("client", msg.getData().getString("reply"));
}
}
}
}
注册Service
<service android:name=".service.MessengerService"
android:process=":remote">
</service>