Messenger信使(跨进程通信)

由Handler发送接收
服务器
Service
public class MyService extends Service {
public MyService() {
}
Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
Log.i("tagserver","--------从客户端传递的数据---------");
Log.i("tagserver","what==="+msg.what+",arg1==="+msg.arg1+",arg2==="+msg.arg2);
Messenger clientMessenger = msg.replyTo;

        Message message = Message.obtain();
        message.what = 2;
        message.arg1 = 999;
        message.arg2 = 8888;

        try {
            clientMessenger.send(message);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
};

//创建服务器端信使对象
Messenger serverMessenger = new Messenger(handler);
@Override
public IBinder onBind(Intent intent) {
    //通过getBinder的方法能够返回连接通道的对象,就是IBinder
    return serverMessenger.getBinder();
}

}
清单注册

<service
            android:name=".MyService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.qf.server"></action>
            </intent-filter>
        </service>

客户端
Mainactivity

public class MainActivity extends AppCompatActivity {

    private Messenger serverMessenger;
    private Messenger clientMessenger;

    Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            Log.i("tagclient","----从服务器端传来的消息----");
            Log.i("tagclient","msg.what=="+msg.what+",arg===="+msg.arg1+",arg2----"+msg.arg2);
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        clientMessenger = new Messenger(handler);    //客户端的信使
    }
//ServiceConnection是一个接口,继承和实现内部类都可以.
    ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            serverMessenger = new Messenger(service);    //服务端的信使
        }
        @Override
        public void onServiceDisconnected(ComponentName name) {

        }
    };
    //绑定服务的要求： 在android5.0之前，使用隐示和显示意图都可以，5.0之后，google官方建议不要使用隐式意图，
    //如果直接使用，会报错。

    @Override
    protected void onStart() {
        super.onStart();
        Intent intent = new Intent();
        intent.setAction("com.qf.server");
        //为了能够让5.0之后的版本，服务可以使用隐士意图必须要加上的语句
        // Service Intent must be explicit: Intent { act=com.qf.server }
        intent.setPackage("com.qianfeng.server");
        bindService(intent,connection,BIND_AUTO_CREATE);
    }
    public void onClick(View view) {
        Message message = Message.obtain();
        message.what = 1;
        message.arg1 = 98;
        message.arg2 = 100;
        message.replyTo = clientMessenger;
        try {
            serverMessenger.send(message);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}

布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.qianfeng.client.MainActivity">

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="向服务器发送消息"
        android:onClick="onClick"/>
</RelativeLayout>