为 Android(安卓)添加 Java 层服务（三）

每一个应用程序都有自己的进程，进程之间不能互相访问，这叫做应用程序沙漏（application sandboxing）
为了能用使应用程序能互相访问,Android提供IPC（interprocess communication protocol）
IPC protocol因为需要整理封装(marshaling/un marshaling数据)而变得复杂。
因此.Android提供 AIDL(Android Interface Definition Language)，它对使用了类似于java的语法,对IPC轻量级实现，并有AIDL工具自动实现stub的创建
实现步骤:
1.定义 the AIDL interface
2.为remote service实现Stub

3.将remote service提供给本地 local client

第一步:定义 the AIDL interface

在项目工程的aidl_service/src/com.tcwzy.aidl/

package com.tcwzy.aidl;interface IStockQuoteService {    double getQuote(String ticker);}

加入后会自动在aidl_service/src/com.tcwzy.aidl/下生成IstockQuoteService.java文件

第二步:为remote service实现Stub

在aidl_service/src/com.tcwzy.service/

package com.tcwzy.service;import com.tcwzy.aidl.IStockQuoteService;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.os.RemoteException;import android.util.Log;public class StockQuoteService extends Service{    private static final String TAG = "wzy";public class StockQuoteServiceImpl extends IStockQuoteService.Stub {    @Override    public double getQuote(String ticker) throws RemoteException {        // TODO Auto-generated method stub        Log.v(TAG,"service getQuote() call for " + ticker);        return 20.0;    }    }    @Override    public void onCreate() {        // TODO Auto-generated method stub        super.onCreate();        Log.v(TAG,"service Create");    }    @Override    public void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        Log.v(TAG,"service Destory");    }    @Override    public void onStart(Intent intent, int startId) {        // TODO Auto-generated method stub        super.onStart(intent, startId);        Log.v(TAG,"service Start");    }    @Override    public IBinder onBind(Intent intent) {        // TODO Auto-generated method stub        Log.v(TAG,"service Bind");        return new StockQuoteServiceImpl();    }}

AndroidManifest.xml为

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.tcwzy.service"      android:versionCode="1"      android:versionName="1.0">    <uses-sdk android:minSdkVersion="9" />    <application android:icon="@drawable/icon" android:label="@string/app_name">            <service android:name="StockQuoteService">                <intent-filter >                 <action android:name="hahaha"/>                 <category android:name="android.intent.category.DEFAULT" />               </intent-filter>            </service>    </application></manifest>

第三步:将remote service提供给本地 local client
利用servcie实现onBind(),就可以连接到remote service

在aidl_client/src/com.tcwzy.aidl下将刚才在服务端创建的aidl文件复制过来

在aidl_client/src/com.tcwzy.client/下声明activity

package com.tcwzy.client;import com.tcwzy.aidl.IStockQuoteService;import android.app.Activity;import android.os.Bundle;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.ServiceConnection;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 android.widget.Toast;public class Aidl_clientActivity extends Activity {    private static final String TAG = "wzy";    private IStockQuoteService stockService = null;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                final Button b1 = (Button)findViewById(R.id.bind);        final Button b2 = (Button)findViewById(R.id.call);        final Button b3 = (Button)findViewById(R.id.unbind);                b1.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                Log.v(TAG,"client bindService called");                Intent intent = new Intent("hahaha");                //Aidl_clientActivity.this.startActivity(intent);                bindService(intent,serConn,Context.BIND_AUTO_CREATE);                Log.v(TAG,"client bindService called serConn: " + IStockQuoteService.class.getName());                Log.v(TAG,"client bindService called serConn: " + serConn);                Log.v(TAG,"client bindService called stockService: " + stockService);                b1.setEnabled(false);                b2.setEnabled(true);                b3.setEnabled(true);            }                    });        b2.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                Log.v(TAG,"client callService called");                callService();                b2.setEnabled(false);            }                    });        b3.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                Log.v(TAG,"client unbindService called");                unbindService(serConn);                b1.setEnabled(true);                b2.setEnabled(false);                b3.setEnabled(false);            }                    });    }        private void callService() {        // TODO Auto-generated method stub        try {            Log.v(TAG,"client callService called");            double val = stockService.getQuote("SYH");            Toast.makeText(Aidl_clientActivity.this, "Value from service is " + val, Toast.LENGTH_SHORT).show();        } catch (RemoteException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }            }    private ServiceConnection serConn = new ServiceConnection() {        @Override        public void onServiceConnected(ComponentName name, IBinder service) {            // TODO Auto-generated method stub            Log.v(TAG,"onServiceConnected called");            stockService = IStockQuoteService.Stub.asInterface(service);                                }                @Override        public void onServiceDisconnected(ComponentName name) {            // TODO Auto-generated method stub            Log.v(TAG,"onServiceDisconnected called");            stockService = null;                    }            };}

AndroidManifest.xml为:

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.tcwzy.client"      android:versionCode="1"      android:versionName="1.0">    <uses-sdk android:minSdkVersion="9" />    <application android:icon="@drawable/icon" android:label="@string/app_name">        <activity android:name=".Aidl_clientActivity"                  android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

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