Android Service之Messenger实现通信

　　If you need to be able to write a Service that can perform complicated communication with clients in remote processes (beyond simply the use of Context.startService to send commands to it), then you can use the Messenger class instead of writing full AIDL files.

Activity：

package org.mobiletrain.messenger;

import android.app.Activity;

public class MainActivity extends Activity {

    private Button bind;
    private Button send;

    private Messenger messenger;
    private Messenger sendMessenger;

    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            System.out.println("acitivty handler");
            super.handleMessage(msg);
        }
    };

    ServiceConnection conn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder binder) {
            messenger = new Messenger(binder);
        }

        @Override
        public void onServiceDisconnected(ComponentName arg0) {

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bind = (Button) findViewById(R.id.bindButton);
        send = (Button) findViewById(R.id.sendButton);

        bind.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setClass(MainActivity.this, MessengerService.class);
                bindService(intent, conn, Context.BIND_AUTO_CREATE);
            }
        });

        send.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                sendMessenger = new Messenger(handler);
                Message msg = Message.obtain(null, 0);
                msg.replyTo = sendMessenger;
                try {
                    messenger.send(msg);
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
        });
    }

}

布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/bindButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="149dp"
        android:text="bind" />
    
    <Button
        android:id="@+id/sendButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/bindButton"
        android:layout_alignLeft="@id/bindButton"
        android:text="send" 
        />

</RelativeLayout>

Service：

package org.mobiletrain.messenger;

import android.app.Service;

public class MessengerService extends Service {

    Messenger replyMessenger = null;
    Messenger messenger = null;

    @Override
    public IBinder onBind(Intent arg0) {
        messenger = new Messenger(handler);
        return messenger.getBinder();
    }

    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 0) {
                replyMessenger = msg.replyTo;
                new MyThread().start();
            }
            super.handleMessage(msg);
        }

    };

    class MyThread extends Thread {
        public void run() {
            System.out.println("Thread start");
            try {
                Thread.sleep(5 * 1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("Thread finish");
            Message msg = Message.obtain(null, 0);
            try {
                replyMessenger.send(msg);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }
}

注册Service：

<service android:name="org.mobiletrain.messenger.MessengerService"></service>