Android(三)：远程Service基本操作

一、Service简介

Service有local和remote两种类型。

local主要是用于本地的应用程序之间的调用，remote主要用于不同应用之间的重用，这里用到AIDL IPC机制。关于AIDL IPC机制可以参阅SDK Dev Guide，很简单！当然，你要是想完全理解这种机制可能要花费点时间哟，不过还好，我只是用一下，呵呵！~ ~

二、Service与进程

android各个组件之间默认运行在同一个进程之中，它们有各自所在的进程来管理，它们是主线程的一部分而不是系统开启的线程。

这么说来，要是在这些组件中做耗时比较长的操作需要另起线程。

这里需要说明，你可以通过android：process=属性说明应用组建的所属进程。

三、远程Service

先看看文件目录结构吧

在对应的包下面新建一个AIDL文件，这里是IMusicService.aidl文件。那么ADT会自动的为你生成对应的java源文件。不要以为 IMusicService.aidl多难写，其实它就是你暴露给外界的接口，只不过我们把他的后缀写为.aidl而不是.java。

IMusicService.aidl文件：

package csdn.blog.myaidl;interface IMusicService { void play(); void stop(); void pause(); }

这样，我们就可以在应用程序中使用它啦...

package csdn.blog;import java.io.IOException;import android.app.Service;import android.content.Intent;import android.media.MediaPlayer;import android.os.IBinder;import android.os.RemoteException;import android.util.Log;import csdn.blog.myaidl.IMusicService;public class MusicPlayerService extends Service {//debugprivate static final String TAG = "Service_06_Remote";private MediaPlayer mPlayer = null;private IMusicService.Stub binder = new IMusicService.Stub() {@Overridepublic void stop() throws RemoteException {// TODO Auto-generated method stubif(mPlayer != null) {mPlayer.stop();try {mPlayer.prepare();} catch (IllegalStateException e) {Log.e(TAG, e.toString());} catch (IOException e) {Log.e(TAG, e.toString());}}}@Overridepublic void play() throws RemoteException {// TODO Auto-generated method stubif(mPlayer == null) {mPlayer = MediaPlayer.create(MusicPlayerService.this, R.raw.tiger);} if(! mPlayer.isPlaying()) {mPlayer.start();}}@Overridepublic void pause() throws RemoteException {// TODO Auto-generated method stubif(mPlayer != null && mPlayer.isPlaying()) {mPlayer.pause();}}};@Overridepublic void onCreate() {// TODO Auto-generated method stub//Log.d(TAG, "MusicPlayerService-->onCreate--onBind");//无效//debug 线程System.out.println("MusicPlayerService Id-->" + Thread.currentThread().getId());System.out.println("MusicPlayerService Name-->" + Thread.currentThread().getName());System.out.println("MusicPlayerService-->onCreate--onBind");super.onCreate();}@Overridepublic IBinder onBind(Intent intent) {// TODO Auto-generated method stubtry {binder.play();} catch (RemoteException e) {Log.e(TAG, e.toString());}//Log.d(TAG, "log MusicPlayerService-->onBind");//无效System.out.println("MusicPlayerService-->onBind");return binder;}@Overridepublic boolean onUnbind(Intent intent) {// TODO Auto-generated method stub//Log.d(TAG, "MusicPlayerService-->onUnbind");//无效System.out.println("MusicPlayerService-->onUnbind");return super.onUnbind(intent);}@Overridepublic void onDestroy() {// TODO Auto-generated method stub//Log.d(TAG, "MusicPlayerService-->onDestroy");//无效System.out.println("MusicPlayerService-->onDestroy");mPlayer.stop();mPlayer.release();super.onDestroy();}}

Activity中我是这样做的：

package csdn.blog;import android.app.Activity;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.os.RemoteException;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import csdn.blog.myaidl.IMusicService;public class Service_06_RemoteAct extends Activity implements OnClickListener{private static final String TAG = "Service_06_RemoteAct";private static final String SERVICE_ACTION = "csdn.blog.MusicPlayerService";private Button btnPlay, btnStop, btnPause, btnExit = null;private IMusicService mIMusicPlayerService = null;private ServiceConnection mConnection = new ServiceConnection() {@Overridepublic void onServiceDisconnected(ComponentName name) {// TODO Auto-generated method stubLog.d(TAG, "onServiceDisconnected()");mIMusicPlayerService = null;}@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {// TODO Auto-generated method stubLog.d(TAG, "onServiceConnected()");mIMusicPlayerService = IMusicService.Stub.asInterface(service);}}; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //debug 线程 System.out.println("main Id-->" + Thread.currentThread().getId());System.out.println("main Name-->" + Thread.currentThread().getName()); btnPlay = (Button)findViewById(R.id.button_play); btnStop = (Button)findViewById(R.id.button_stop); btnPause = (Button)findViewById(R.id.button_pause); btnExit = (Button)findViewById(R.id.button_exit); btnPlay.setOnClickListener(this); btnStop.setOnClickListener(this); btnPause.setOnClickListener(this); btnExit.setOnClickListener(this); connection(); } @Overrideprotected void onDestroy() {// TODO Auto-generated method stubLog.d(TAG, "onDestroy-->unbindService");unbindService(mConnection);super.onDestroy();}private void connection() {// TODO Auto-generated method stubLog.d(TAG, "bindService");bindService(new Intent(SERVICE_ACTION), mConnection, Context.BIND_AUTO_CREATE);}@Overridepublic void onClick(View v) {// TODO Auto-generated method stubswitch(v.getId()) {case R.id.button_play:try {mIMusicPlayerService.play();} catch (RemoteException e) {Log.e(TAG, e.toString());}break;case R.id.button_stop:try {mIMusicPlayerService.stop();} catch (RemoteException e) {Log.e(TAG, e.toString());}break;case R.id.button_pause:try {mIMusicPlayerService.pause();} catch (RemoteException e) {Log.e(TAG, e.toString());}break;case R.id.button_exit:finish();break;default:break;}}}

最后，别忘记在manifest.xm文件中声明：

<service android:name=".MusicPlayerService" android:process=":remote"><intent-filter><action android:name="csdn.blog.MusicPlayerService"/></intent-filter></service

cmd一下，在命令行中adb shell ps 查看 android 应用程序的 PID 以及进程 ID。

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