016_03浅谈远程Service和AIDL

　　 如果需要访问不同进程间service中的数据或者方法，需要使用AIDL(android interface description language)工具，可以通过如下方法： 

        public boolean bindService(Intent intent, ServiceConnection conn, int flags) ； 
        public void unbindService(ServiceConnection conn); 

        intent是跳转到service的intent，conn是与service连接状态的类。如果想要访问service中的数据，可以在onServiceConnected()方法中进行实现。

　　 当开发Service类时，该Service类必须提供一个IBinder onBind(Intent intent)方法，在绑定本地Service的情况下，onBind（Intent intent）方法所返回的Ibinder对象将会传给ServiceConnection对象里onServiceConnected（ComponentName name, IBinder service)方法的service参数，这样访问者就可通过该IBinder对象与service进行通信。

　　如果另外一个进程想访问上图MyService.java中getruntimeinfo()方法

    public String getruntimeinfo(){
        String info = "momory usage 5%";
        return info;
    }

则需要以下步骤：

1，新建一个interface

package com.example.day16_04remoteservicedemo;

public interface MyRemoteService {
     public String forworadgetruntimeinfo();
}

2，到源程序目录下找到MyRemoteService.java，直接将后缀名改为.aidl并保存

3，刷新project，可看到eclipse中报错

4，去掉public，保存；可看到在gen下自动生成MyRemoteService.java

5，在MyService.java中新建一个内部类RemoteBinder继承自MyRemoteService.java中的Stub类

    class RemoteBinder extends  Stub{
        @Override
        public String forworadgetruntimeinfo() throws RemoteException {    
            return getruntimeinfo();
        }
    }

 6，在AndroidManifest.xml中配置service

        <service android:name=".MyService">
             <intent-filter>
                    <action android:name="com.cskaoyan.service" />
             </intent-filter>           
        </service>

被访问的service源代码如下：

package com.example.day16_04remoteservicedemo;

import com.example.day16_04remoteservicedemo.MyRemoteService.Stub;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
 
public class MyService extends Service {
    IBinder binder ;
    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        System.out.println("MyService.onBind()");
        //当且仅当此处返回一个非空的Ibinder对象时，bindservice一端的Connection内的onserviceConnected函数才会被系统call到
        return  new RemoteBinder();
    }
    
    public String getruntimeinfo(){
        String info = "momory usage 5%";
        return info;
    }

    @Override
    public boolean onUnbind(Intent intent) {
        // TODO Auto-generated method stub
        System.out.println("MyService.onUnbind()");
        return super.onUnbind(intent);
    }

    @Override
    public void onRebind(Intent intent) {
        // TODO Auto-generated method stub
        super.onRebind(intent);
        System.out.println("MyService.onRebind()");
    }

    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        System.out.println("MyService.onCreate()");
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        System.out.println("MyService.onDestroy()");
    }

    class RemoteBinder extends  Stub{
        @Override
        public String forworadgetruntimeinfo() throws RemoteException {
            // TODO Auto-generated method stub
            return getruntimeinfo();
        }    
    }
}

MyRemoteService.aidl

package com.example.day16_04remoteservicedemo;

 interface MyRemoteService {
     String forworadgetruntimeinfo();
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.day16_04remoteservicedemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="21" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <service android:name=".MyService">
            <intent-filter>
                <action android:name="com.cskaoyan.service" />
             </intent-filter>           
        </service>
    </application>

</manifest>

然后再来写客户端：

将com.example.day16_04remoteservicedemo下的MyRemoteService.aidl直接拷贝过来，放置位置如下图：

最重要的一步是如何在OnServiceConnected方法中得到一个IBinder对象

    class MyConnection implements ServiceConnection{

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            //binder= (Stub) service;不可行    
            //因为绑定远程Service的ServiceConnection并不能直接获取Service的OnBind()
            //方法返回的对象，它只能返回OnBind()方法所返回的对象的代理
            myRemoteService = MyRemoteService.Stub.asInterface(service);
            // TODO Auto-generated method stub
            System.out.println("MainActivity.MyConnection.onServiceConnected()");
        }

源代码如下：

package com.example.day16_05otherapplication;

import com.example.day16_04remoteservicedemo.MyRemoteService;
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.view.View;

public class MainActivity extends Activity {

    MyConnection conn;
    MyRemoteService myRemoteService;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    
    public void bindservice(View v){
        Intent intent = new Intent();
        intent.setAction("com.cskaoyan.service");
        conn=new MyConnection();
        bindService(intent, conn, Context.BIND_AUTO_CREATE);
        
    }
    public void unbindservice(View v){
        unbindService(conn);
        conn=null;    
    }
    
    public void remotecall(View v) throws RemoteException{    
        System.out.println(myRemoteService.forworadgetruntimeinfo());
        String info = myRemoteService.forworadgetruntimeinfo();
        System.out.println("MainActivity.remotecall()"+info);
    }
    
    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        if (conn!=null) {
           unbindService(conn);    
        }
    }
    
    class MyConnection implements ServiceConnection{

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            //binder= (Stub) service;不可行    
            //因为绑定远程Service的ServiceConnection并不能直接获取Service的OnBind()
            //方法返回的对象，它只能返回OnBind()方法所返回的对象的代理
            myRemoteService = MyRemoteService.Stub.asInterface(service);
            // TODO Auto-generated method stub
            System.out.println("MainActivity.MyConnection.onServiceConnected()");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub
            System.out.println("MainActivity.MyConnection.DisConnected()");
        }    
    }     
}

<LinearLayout 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="com.example.day16_05otherapplication.MainActivity"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    
     <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="绑定服务" 
        android:onClick="bindservice"/>
        
     <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="解除绑定"
        android:onClick="unbindservice" />
     <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="调用远程的方法" 
        android:onClick="remotecall"/>
</LinearLayout>

当点击“绑定服务后”，再点击“调用远程的方法”，就可以获取MyService.java中 getruntimeinfo()方法中的String  “momory usage 5%”