Messenger信使

public class MainActivity extends AppCompatActivity {
private Intent intent;
private MyServiceConnection serviceConnection;
private Messenger messenger;//信使。
private Messenger activity_messenger;//
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
String str = (String) msg.obj;
System.out.println(str);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
activity_messenger = new Messenger(handler);
//绑定服务。
intent = new Intent(this,MyService.class);
serviceConnection = new MyServiceConnection();
bindService(intent, serviceConnection,BIND_AUTO_CREATE);
}
public void click(View view){
if(messenger!=null){
Message msg = new Message();
msg.obj = "我是activity发送过来的消息";
msg.replyTo =activity_messenger;
try {
messenger.send(msg);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
class MyServiceConnection implements ServiceConnection{

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
//得到信使。service的信使.
messenger = new Messenger(service);
}

@Override
public void onServiceDisconnected(ComponentName name) {

}
}
}

public class MyService extends Service {
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
String str = (String) msg.obj;
System.out.println(str);
//发送消息。
Messenger activity_messenger =  msg.replyTo;
Message message = new Message();
message.obj="我是service发送过来的消息";
try {
activity_messenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
};
@Override
public IBinder onBind(Intent intent) {
Messenger messenger = new Messenger(handler);
return messenger.getBinder();
}
}