Android四大组件之Service

Android四大组件之Service

       Android支持服务的概念，服务是在后台运行的组件，没有用户界面，Android服务可用有与活动独立的生命周期。Android支持两种类型的服务：

本地服务：

      本地服务只能由承载该服务的应用程序访问，无法供在设备上运行的其他应用程序访问。客户端调用Context.startService()启动该服务。

远程服务：

      远程服务除了可从承载服务的应用程序访问，还可以从其他应用程序访问。远程服务使用AIDL向客户端定义。服务支持onBind()方法，客户端通过Context.bindService()进行调用。

 

1）本地服务

1.1、startService  

      本地服务可由Context.startService()启动，启动后这些服务将持续运行，直到客户端调用Context.stopService()或服务自己调用stopSelf()。

      注意：如果调用Context.startService()时还未创建服务，系统将实例化服务并调用服务的onStartCommand()方法。如果在调用Context.startService()时服务已经启动，那么不会再创建一个实例，而是重新调用正在运行的服务的onStartCommand()方法。

      Demo:我们在MainActivity中新建两个两个Button，一个用于启动服务，另外一个用于停止服务。建立一个MyService类继承于Service，当收到服务的时候在通知栏弹出通知，一直到我们的服务退出才清除通知，同时收到启动服务的消息时我们建立一个线程sleep 10秒。当我们退出MainActivity的时候停止服务，同时清除通知栏的通知。

MainActivity.xml：就两个Button用于启动和停止服务。

<SPAN style="FONT-SIZE: 14px"><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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btnStart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="startService" >
    </Button>

    <Button
        android:id="@+id/btnStop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="stopService"
        android:layout_below="@id/btnStart">
    </Button>

</RelativeLayout></SPAN>

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btnStart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="startService" >
    </Button>
    
    <Button
        android:id="@+id/btnStop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="stopService" 
        android:layout_below="@id/btnStart">
    </Button>

</RelativeLayout>

然后是MainActivity，用于响应Button的单击事件：

<SPAN style="FONT-SIZE: 14px">public class MainActivity extends Activity implements OnClickListener{

    private static final String TAG = "MainActivity";
    private int counter = 1;
    private Button btnStart, btnStop;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnStart = (Button)this.findViewById(R.id.btnStart);
        btnStop = (Button)this.findViewById(R.id.btnStop);
        btnStart.setOnClickListener(this);
        btnStop.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        Log.v(TAG, "id:"+v.getId() + "btn:"+R.id.btnStart);
        switch (v.getId()) {
        case R.id.btnStart:
            Log.v(TAG, "Starting Service...counter=" + counter);
            Intent intent = new Intent(MainActivity.this, MyService.class);
            intent.putExtra("counter", counter);
            startService(intent);
            break;

        case R.id.btnStop:
            Log.v(TAG, "Stopping Service...");
            if( stopService(new Intent(MainActivity.this, MyService.class)) ) {
                Log.v(TAG, "stopService successful");
            } else {
                Log.v(TAG, "stopService failed");
            }
            break;

        default:
            break;
        }
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        stopService(new Intent(MainActivity.this, MyService.class));
        super.onDestroy();
    }
}</SPAN>

public class MainActivity extends Activity implements OnClickListener{

	private static final String TAG = "MainActivity";
	private int counter = 1;
	private Button btnStart, btnStop;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		btnStart = (Button)this.findViewById(R.id.btnStart);
		btnStop = (Button)this.findViewById(R.id.btnStop);
		btnStart.setOnClickListener(this);
		btnStop.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		Log.v(TAG, "id:"+v.getId() + "btn:"+R.id.btnStart);
		switch (v.getId()) {
		case R.id.btnStart:
			Log.v(TAG, "Starting Service...counter=" + counter);
			Intent intent = new Intent(MainActivity.this, MyService.class);
			intent.putExtra("counter", counter);
			startService(intent);
			break;

		case R.id.btnStop:
			Log.v(TAG, "Stopping Service...");
			if( stopService(new Intent(MainActivity.this, MyService.class)) ) {
				Log.v(TAG, "stopService successful");
			} else {
				Log.v(TAG, "stopService failed");
			}
			break;
			
		default:
			break;
		}
	}
	
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		stopService(new Intent(MainActivity.this, MyService.class));
		super.onDestroy();
	}
}

最后是我们的MyService，当收到服务的时候，在通知栏弹出通知，并启动一个sleep 10秒的线程。

<SPAN style="FONT-SIZE: 14px">public class MyService extends Service {

    private static final String TAG = "MyService";
    private NotificationManager notificationMgr;
    private ThreadGroup threadGroup = new ThreadGroup("ServiceWorkder");

    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        Log.v(TAG, "in onCreate");
        notificationMgr = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        Notification notification = new Notification(R.drawable.ic_launcher, "Service is running", System.currentTimeMillis());
        notification.flags = Notification.FLAG_NO_CLEAR;
        PendingIntent intent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);
        notification.setLatestEventInfo(this, TAG, "Service is running", intent);
        notificationMgr.notify(0, notification);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // TODO Auto-generated method stub
        super.onStartCommand(intent, flags, startId);

        int counter = intent.getExtras().getInt("counter");
        Log.v(TAG, "in onStartCommand, counter = "+counter+",startId = "+startId);
        new Thread(threadGroup, new ServiceWorker(counter)).start();
        return START_STICKY;
    }

    class ServiceWorker implements Runnable {
        private int counter = -1;

        public ServiceWorker(int counter) {
            this.counter = counter;
        }

        public void run() {
            final String TAG = "ServiceWorker" + Thread.currentThread().getId();
            try {
                Log.v(TAG, "Sleeping for 10 seconds.counter="+counter);
                Thread.sleep(10000);
                Log.v(TAG, "...waking up");
            } catch (Exception e) {
                // TODO: handle exception
                Log.v(TAG, "...sleep interrupt");
            }
        }
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        Log.v(TAG, "in onDestroy. Interrupt threads and canceling notifications");
        threadGroup.interrupt();
        notificationMgr.cancelAll();
        super.onDestroy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

}</SPAN>

public class MyService extends Service {

	private static final String TAG = "MyService";
	private NotificationManager notificationMgr;
	private ThreadGroup threadGroup = new ThreadGroup("ServiceWorkder"); 
	
	@Override
	public void onCreate() {
		// TODO Auto-generated method stub
		super.onCreate();
		Log.v(TAG, "in onCreate");
		notificationMgr = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
		Notification notification = new Notification(R.drawable.ic_launcher, "Service is running", System.currentTimeMillis());
		notification.flags = Notification.FLAG_NO_CLEAR;
		PendingIntent intent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);
		notification.setLatestEventInfo(this, TAG, "Service is running", intent);
		notificationMgr.notify(0, notification);
	}
	
	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		// TODO Auto-generated method stub
		super.onStartCommand(intent, flags, startId);
		
		int counter = intent.getExtras().getInt("counter");
		Log.v(TAG, "in onStartCommand, counter = "+counter+",startId = "+startId);
		new Thread(threadGroup, new ServiceWorker(counter)).start();
		return START_STICKY;
	}

	class ServiceWorker implements Runnable {
		private int counter = -1;
		
		public ServiceWorker(int counter) {
			this.counter = counter;
		}
		
		public void run() {
			final String TAG = "ServiceWorker" + Thread.currentThread().getId();
			try {
				Log.v(TAG, "Sleeping for 10 seconds.counter="+counter);
				Thread.sleep(10000);
				Log.v(TAG, "...waking up");
			} catch (Exception e) {
				// TODO: handle exception
				Log.v(TAG, "...sleep interrupt");
			}
		}
	}
	
	@Override
	public void onDestroy() {
		// TODO Auto-generated method stub
		Log.v(TAG, "in onDestroy. Interrupt threads and canceling notifications");
		threadGroup.interrupt();
		notificationMgr.cancelAll();
		super.onDestroy();
	}
	
	@Override
	public IBinder onBind(Intent intent) {
		// TODO Auto-generated method stub
		return null;
	}

}

最后不要忘了在AndroidManifest.xml中声明我们的Service:

<SPAN style="FONT-SIZE: 14px">        <service
            android:name=".MyService">
        </service></SPAN>

        <service 
            android:name=".MyService">
        </service>

 

最后通知栏运行效果如下：

 

1.2、bindService

        本地服务也可由Context.bindService()启动，这样调用者和服务绑在一起，调用者一旦退出，服务也就终止了。客户端建立一个与Service连接，使用此连接与Service通信，通过Context.bindService()绑定服务，使用Context.unbindService()关闭服务。多个客户端可以绑定同一个服务，如果Service未启动，bindService()可以启动服务。

       注意：上面的startService()和bindService()是完全独立的两种模式，你可以绑定一个已经通过startService()启动的服务。例如：一个后台播放音乐的服务可以通过startService()启动播放，然后activity可以通过调用bindService()方法建立于Service的联系，执行切换歌曲等操作。这种情况下：stopService()不会停止服务，直到最后一个unbindService()调用。

      当创建一个能够提供绑定功能的服务时，我们必须提供一个IBinder对象，客户端能够使用这个对象与服务通信，Android中有三种方式：

（1）扩展Binder类

          一般用于服务和Activity属于同一个进程的情况。类似上面的startService()我们在MainActivity中建立两个Button，一个用于bindService,另外一个unbindService()。在获得Service的IBinder接口之后就可以调用Service的内部方法了。

<SPAN style="FONT-SIZE: 14px">public class MainActivity extends Activity implements OnClickListener{

    private static final String TAG = "MainActivity";
    private boolean isBindFlag = false;
    private Button btnBind, btnUnbind;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnBind = (Button)this.findViewById(R.id.btnBind);
        btnUnbind = (Button)this.findViewById(R.id.btnUnbind);
        btnBind.setOnClickListener(this);
        btnUnbind.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {

        case R.id.btnBind:
            Intent intent2 = new Intent(MainActivity.this, MyBindService.class);
            bindService(intent2, serviceConnection, Context.BIND_AUTO_CREATE);
            break;

        case R.id.btnUnbind:
            unbindService(serviceConnection);
            break;
        default:
            break;
        }
    }
    private ServiceConnection serviceConnection = new ServiceConnection() {

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub
            isBindFlag = false;
        }

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            // TODO Auto-generated method stub
            MyBindService.MyBinder binder = (MyBinder)service;
            MyBindService bndService = binder.getService();
            bndService.myMethod();
            isBindFlag = true;
        }
    };

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        if(isBindFlag == true) {
            unbindService(serviceConnection);
        }
        super.onDestroy();
    }
}</SPAN>

public class MainActivity extends Activity implements OnClickListener{

	private static final String TAG = "MainActivity";
	private boolean isBindFlag = false;
	private Button btnBind, btnUnbind;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		btnBind = (Button)this.findViewById(R.id.btnBind);
		btnUnbind = (Button)this.findViewById(R.id.btnUnbind);
		btnBind.setOnClickListener(this);
		btnUnbind.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		
		case R.id.btnBind:
			Intent intent2 = new Intent(MainActivity.this, MyBindService.class);
			bindService(intent2, serviceConnection, Context.BIND_AUTO_CREATE);
			break;
			
		case R.id.btnUnbind:
			unbindService(serviceConnection);
			break;
		default:
			break;
		}
	}
	private ServiceConnection serviceConnection = new ServiceConnection() {
		
		@Override
		public void onServiceDisconnected(ComponentName name) {
			// TODO Auto-generated method stub
			isBindFlag = false;
		}
		
		@Override
		public void onServiceConnected(ComponentName name, IBinder service) {
			// TODO Auto-generated method stub
			MyBindService.MyBinder binder = (MyBinder)service;
			MyBindService bndService = binder.getService();
			bndService.myMethod();
			isBindFlag = true;
		}
	};
	
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		if(isBindFlag == true) {
			unbindService(serviceConnection);
		}
		super.onDestroy();
	}
}

        这里当绑定到MyBindService之后，就可以通过bndService实例调用其方法myMethod()了。下面MyBindService比较简单就是继承于Service，并实现其onBind()接口，返回一个MyBinder实例，客户端拿到这个MyBinder之后可以通过它获取到MyBindService实例，然后调用其提供的myMethod()方法了。

 

<SPAN style="FONT-SIZE: 14px">public class MyBindService extends Service {

    private static final String TAG = "MyBindService";

    public void myMethod() {
        Log.i(TAG, "myBindService->myMethod()");
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return myBinder;
    }

    public class MyBinder extends Binder {

        public MyBindService getService() {
            return MyBindService.this;
        }
    }

    private MyBinder myBinder = new MyBinder();
}</SPAN>

public class MyBindService extends Service {

	private static final String TAG = "MyBindService";
	
	public void myMethod() {
		Log.i(TAG, "myBindService->myMethod()");
	}
	
	@Override
	public IBinder onBind(Intent intent) {
		// TODO Auto-generated method stub
		return myBinder;
	}
	
	public class MyBinder extends Binder {
		
		public MyBindService getService() {
			return MyBindService.this;
		}
	}

	private MyBinder myBinder = new MyBinder();
}

 

     同理最后我们也需要在AndroidManifest.xml中声明我们的服务。

 

（2）使用Messenger

 

 

（3）Remote Service 也就是我们下面要说的AIDL服务了。

 

2）AIDL服务     

 

2.1）构建远程服务  

      上面介绍的各种服务只能由承载它的应用程序使用，如果想构建可由其他进程通过RPC使用的服务，需要使用IDL来定义向客户端公开的接口，在Android中这个IDL就称为AIDL。构建远程服务的一般步骤为：

 

1、编写一个AIDL文件用来向客户端定义接口。AIDL文件使用Java语法扩展名为.aidl，其内部使用的包名和Android项目使用的包名相同。

       首先在项目的src目录下新建一个IStudentInfo.aidl文件，在AIDL文件中定义服务接口。提供了double getScore(String name)接口，根据给定的String类型的学生姓名，返回一个double类型的分数。

      

package com.myAndroid.aidlService;

interface IStudentInfoService {
    double getScore(String name);
}

package com.myAndroid.aidlService;

interface IStudentInfoService {
	double getScore(String name);
}

      

 

2、将AIDL文件添加到Eclipse项目的src目录下，Android Eclipse插件将调用AIDL编译器从AIDL文件生成Java接口。

 

       生成的java接口文件位于gen/com.myAndroid.aidlService下，名为IStudengInfoService.java：

/*
 * This file is auto-generated.  DO NOT MODIFY.
 * Original file: C:\Documents and Settings\Administrator\workspace\Android使用AIDL创建Service\src\com\myAndroid\aidlService\IStudentInfoService.aidl
 */
package com.myAndroid.aidlService;
public interface IStudentInfoService extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.myAndroid.aidlService.IStudentInfoService
{
private static final java.lang.String DESCRIPTOR = "com.myAndroid.aidlService.IStudentInfoService";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
 * Cast an IBinder object into an com.myAndroid.aidlService.IStudentInfoService interface,
 * generating a proxy if needed.
 */
public static com.myAndroid.aidlService.IStudentInfoService asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof com.myAndroid.aidlService.IStudentInfoService))) {
return ((com.myAndroid.aidlService.IStudentInfoService)iin);
}
return new com.myAndroid.aidlService.IStudentInfoService.Stub.Proxy(obj);
}
@Override public android.os.IBinder asBinder()
{
return this;
}
@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
{
switch (code)
{
case INTERFACE_TRANSACTION:
{
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_getScore:
{
data.enforceInterface(DESCRIPTOR);
java.lang.String _arg0;
_arg0 = data.readString();
double _result = this.getScore(_arg0);
reply.writeNoException();
reply.writeDouble(_result);
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements com.myAndroid.aidlService.IStudentInfoService
{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
{
mRemote = remote;
}
@Override public android.os.IBinder asBinder()
{
return mRemote;
}
public java.lang.String getInterfaceDescriptor()
{
return DESCRIPTOR;
}
@Override public double getScore(java.lang.String name) throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
double _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
_data.writeString(name);
mRemote.transact(Stub.TRANSACTION_getScore, _data, _reply, 0);
_reply.readException();
_result = _reply.readDouble();
}
finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
}
static final int TRANSACTION_getScore = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
}
public double getScore(java.lang.String name) throws android.os.RemoteException;
}

/*
 * This file is auto-generated.  DO NOT MODIFY.
 * Original file: C:\Documents and Settings\Administrator\workspace\Android使用AIDL创建Service\src\com\myAndroid\aidlService\IStudentInfoService.aidl
 */
package com.myAndroid.aidlService;
public interface IStudentInfoService extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.myAndroid.aidlService.IStudentInfoService
{
private static final java.lang.String DESCRIPTOR = "com.myAndroid.aidlService.IStudentInfoService";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
 * Cast an IBinder object into an com.myAndroid.aidlService.IStudentInfoService interface,
 * generating a proxy if needed.
 */
public static com.myAndroid.aidlService.IStudentInfoService asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof com.myAndroid.aidlService.IStudentInfoService))) {
return ((com.myAndroid.aidlService.IStudentInfoService)iin);
}
return new com.myAndroid.aidlService.IStudentInfoService.Stub.Proxy(obj);
}
@Override public android.os.IBinder asBinder()
{
return this;
}
@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
{
switch (code)
{
case INTERFACE_TRANSACTION:
{
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_getScore:
{
data.enforceInterface(DESCRIPTOR);
java.lang.String _arg0;
_arg0 = data.readString();
double _result = this.getScore(_arg0);
reply.writeNoException();
reply.writeDouble(_result);
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements com.myAndroid.aidlService.IStudentInfoService
{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
{
mRemote = remote;
}
@Override public android.os.IBinder asBinder()
{
return mRemote;
}
public java.lang.String getInterfaceDescriptor()
{
return DESCRIPTOR;
}
@Override public double getScore(java.lang.String name) throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
double _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
_data.writeString(name);
mRemote.transact(Stub.TRANSACTION_getScore, _data, _reply, 0);
_reply.readException();
_result = _reply.readDouble();
}
finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
}
static final int TRANSACTION_getScore = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
}
public double getScore(java.lang.String name) throws android.os.RemoteException;
}

       对于所生成的类，注意几点：在IStudentInfoService中有一个名为IStudentInfoService的接口，实现了IInterface接口。

       内部有一个名为Stub的static final 抽象类扩展了android.os.Binder并实现了IStudentInfoService接口。

       内部还有一个名为Proxy的static类，实现了IStudentInfoService接口，它是Stub类的代理。      

3、实现一个服务并从onBind()方法返回所生成的接口。

 

      要实现服务的接口，需要编写一个类来扩展android.app.Service并实现IStudentInfoService接口，这个类需要提供onBind()方法将服务向客户端公开。

package com.myAndroid.aidlService;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

public class StudentInfoService extends Service {

    private static final String TAG = "StudentInfoService";

    public class StudentInfoServiceImpl extends IStudentInfoService.Stub {

        @Override
        public double getScore(String name) throws RemoteException {
            // TODO Auto-generated method stub
            Log.v(TAG, "getScore() called for "+ name);
            return 85.0;
        }
    }

    @Override
    public IBinder onBind(Intent arg0) {
        // TODO Auto-generated method stub
        Log.v(TAG, "onBind called");
        return new StudentInfoServiceImpl();
    }
}

package com.myAndroid.aidlService;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

public class StudentInfoService extends Service {

	private static final String TAG = "StudentInfoService";
	
	public class StudentInfoServiceImpl extends IStudentInfoService.Stub {

		@Override
		public double getScore(String name) throws RemoteException {
			// TODO Auto-generated method stub
			Log.v(TAG, "getScore() called for "+ name);
			return 85.0;
		}
	}
	
	@Override
	public IBinder onBind(Intent arg0) {
		// TODO Auto-generated method stub
		Log.v(TAG, "onBind called");
		return new StudentInfoServiceImpl();
	}
}

        从AIDL文件生成的Stub类是抽象类，且实现了IStudentInfoService接口。在我们的服务实现中内部类StudentInfoServiceIml扩展了Stub类，实现了getScore()方法，充当着远程服务具体实现，当客户端bind到服务时，返回一个此类的实例。

 

4、最后将服务配置添加到AndroidManifest.xml文件中

       这次我们需要用一个Intent过滤器来公开服务。

<service android:name="StudentInfoService">
          <intent-filter >
              <action android:name="com.myAndroid.aidlService.IStudentInfoService"/>
          </intent-filter>
      </service>

  <service android:name="StudentInfoService">
            <intent-filter >
                <action android:name="com.myAndroid.aidlService.IStudentInfoService"/>
            </intent-filter>
        </service>

2.2）调用远程服务  

       当客户端与服务通信时，它们之间需要一个协议或契约，在Android中这个协议就是AIDL文件。所以客户端调用服务的第一步就是获取服务的AIDL文件并将其复制到客户端项目中，同理AIDL编译器会创建一个接口定义公开文件，这个文件与服务器中的文件一样。

      我们创建一个新的Android项目名为 StudentInfoClient，包名为com.myAndroid.studentInfoClient。然后在这个项目下新建一个Java包名为

com.myAndroid.aidlService，并将IStudentInfoService.aidl文件拷贝到当前包下面。

     最后我们在MainActivity中通过bindService()获取服务的引用，然后调用其getScore()方法，即可跟服务端通信。下面给出客户端源码：

         

package com.myAndroid.studentInfoClient;

import com.myAndroid.aidlService.IStudengInfoService;

import android.os.Bundle;
import android.os.IBinder;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.support.v4.widget.SimpleCursorAdapter.ViewBinder;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import android.widget.ToggleButton;

public class MainActivity extends Activity implements View.OnClickListener {

    private ToggleButton toggleButton;
    private Button callButton;
    private IStudengInfoService myService = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toggleButton = (ToggleButton)this.findViewById(R.id.bindBtn);
        callButton = (Button)this.findViewById(R.id.callBtn);
        toggleButton.setOnClickListener(this);
        callButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.bindBtn:
            if(((ToggleButton)v).isChecked()) {
                bindService(new Intent(IStudengInfoService.class.getName()), conn, Context.BIND_AUTO_CREATE);
            } else {
                unbindService(conn);
                callButton.setEnabled(false);
            }
            break;

        case R.id.callBtn:
            callService();
            break;
        default:
            break;
        }
    }

    private void callService() {
        try {
            double val = myService.getScore("Lucy");
            Toast.makeText(MainActivity.this, "Value from service is "+ val, Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            // TODO: handle exception
        }
    }

    private ServiceConnection conn = new ServiceConnection() {

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub
            myService = null;
            toggleButton.setChecked(false);
            callButton.setEnabled(false);
        }

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            // TODO Auto-generated method stub
            myService = IStudengInfoService.Stub.asInterface(service);
            toggleButton.setChecked(true);
            callButton.setEnabled(true);
        }
    };

    protected void onDestroy() {
        if(callButton.isEnabled()) {
            unbindService(conn);
        }
        super.onDestroy();
    }
}

package com.myAndroid.studentInfoClient;

import com.myAndroid.aidlService.IStudengInfoService;

import android.os.Bundle;
import android.os.IBinder;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.support.v4.widget.SimpleCursorAdapter.ViewBinder;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import android.widget.ToggleButton;

public class MainActivity extends Activity implements View.OnClickListener {

	private ToggleButton toggleButton;
	private Button callButton;
	private IStudengInfoService myService = null;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		toggleButton = (ToggleButton)this.findViewById(R.id.bindBtn);
		callButton = (Button)this.findViewById(R.id.callBtn);
		toggleButton.setOnClickListener(this);
		callButton.setOnClickListener(this);
	}
	
	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		case R.id.bindBtn:
			if(((ToggleButton)v).isChecked()) {
				bindService(new Intent(IStudengInfoService.class.getName()), conn, Context.BIND_AUTO_CREATE);
			} else {
				unbindService(conn);
				callButton.setEnabled(false);
			}
			break;

		case R.id.callBtn:
			callService();
			break;
		default:
			break;
		}
	}
	
	private void callService() {
		try {
			double val = myService.getScore("Lucy");
			Toast.makeText(MainActivity.this, "Value from service is "+ val, Toast.LENGTH_LONG).show();
		} catch (Exception e) {
			// TODO: handle exception
		}
	}

	private ServiceConnection conn = new ServiceConnection() {
		
		@Override
		public void onServiceDisconnected(ComponentName name) {
			// TODO Auto-generated method stub
			myService = null;
			toggleButton.setChecked(false);
			callButton.setEnabled(false);
		}
		
		@Override
		public void onServiceConnected(ComponentName name, IBinder service) {
			// TODO Auto-generated method stub
			myService = IStudengInfoService.Stub.asInterface(service);
			toggleButton.setChecked(true);
			callButton.setEnabled(true);
		}
	};
	
	protected void onDestroy() {
		if(callButton.isEnabled()) {
			unbindService(conn);
		}
		super.onDestroy();
	}
}

         代码中对于AIDL服务我们需要提供ServiceConnection接口的实现，此接口定义两个方法：一个供系统建立服务连接时调用，另一个在销毁服务连接时调用。当建立服务时回调onServiceConnected()方法，我们根据参数service调用IStudengInfoService.Stub.asInterface()获得服务端的代理，然后调用其相应方法getScore()。

        注意：bindService()是异步调用，因为进程或服务可能没有运行，但是我们不能在主线程上等待服务启动。当从服务解除绑定时我们不会调用onServiceDisConnected()，只有在服务崩溃时才会调用它。如果调用了它，我们可能需要重写调用bindService()。

2.3）向服务传递复杂类型

注意：AIDL对非原语的支持：

 1、AIDL支持String和CharSequence。

 2、AIDL支持传递其他AIDL接口，但你引用的每个AIDL接口都需要一个import语句。

 3、AIDL支持传递实现android.os.Parcelable接口的复杂类型。需要在AIDL文件中包含针对这些类型的Import语句。

 4、AIDL支持java.util.List和java.util.Map，但是具有一些限制，集合中的项允许数据类型包括Java原语、String、CharSequence和android.os.Parcelable。无需为List和Map提供import语句，但是需要为Parcelable提供。

 5、除字符串外。非原语类型需要一个方向指示符。方向指示符包括in、out和inout。in表示由客户端设置，out表示值由服务设置，inout表示客户端和服务都设置了该值。

 Parcelable接口告诉Android运行时在封送marshalling和解unmarshalling过程中如何序列化和反序列化对象。

public class Person implements Parcelable {

    private int age;
    private String name;

    public static final Parcelable.Creator<Person> CREATOR = new Parcelable.Creator<Person>() {

        public Person createFromParcel(Parcel in) {
            return new Person(in);
        }

        public Person[] newArray(int size) {
            return new Person[size];
        }
    };

    public Person() {
    }

    private Person(Parcel in) {
        readFromParcel(in);
    }

    @Override
    public int describeContents() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        // TODO Auto-generated method stub
        dest.writeInt(age);
        dest.writeString(name);
    }

    public void readFromParcel(Parcel in) {
        age = in.readInt();
        name = in.readString();
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

public class Person implements Parcelable {

	private int age;
	private String name;
		
	public static final Parcelable.Creator<Person> CREATOR = new Parcelable.Creator<Person>() {
			
		public Person createFromParcel(Parcel in) {
			return new Person(in);
		}
		
		public Person[] newArray(int size) {
			return new Person[size];
		}
	};
		
	public Person() {
	}
	
	private Person(Parcel in) {
		readFromParcel(in);
	}
	
	@Override
	public int describeContents() {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public void writeToParcel(Parcel dest, int flags) {
		// TODO Auto-generated method stub
		dest.writeInt(age);
		dest.writeString(name);
	}
	
	public void readFromParcel(Parcel in) {
		age = in.readInt();
		name = in.readString();
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
}

        Parcelable接口定义在封送/解封送过程中混合和分解对象的契约，Parcelable接口的底层是Parcel容器对象，Parcel类是一种最快的序列号和反序列化机制，专为Android中的进程间通信而设计。

       要实现Parcelable接口，需要实现writeToParecl()和readFromParcel()方法。写入对象到包裹和从包裹中读取对象，注意：写入属性的顺序和读取属性的顺序必须相同。

       向Person类添加一个名为CREATOR的static final属性，该属性需要实现android.os.Parcelable.Creator<T>接口。

       为Parcelable提供一个构造函数，知道如何从Parcel创建对象。

      在.aidl文件中我们需要导入该类：import com.myAndroid.aidlService.Person。

      interface IStudentInfoServie{

                 String getScore(in String name, in Person requester);    // 后面非原语类型需要一个方向指示符。

      }