Android中如何利用AIDL机制调用远程服务

在Android中,每个应用程序都有自己的进程，当需要在不同的进程之间传递对象时，该如何实现呢?显然, Java中是不支持跨进程内存共享的。因此要传递对象,需要把对象解析成操作系统能够理解的数据格式,以达到跨界对象访问的目的。在JavaEE中，采用RMI通过序列化传递对象。在Android中,则采用AIDL(Android Interface DefinitionLanguage：接口描述语言)方式实现。

AIDL是一种接口定义语言，用于约束两个进程间的通讯规则，供编译器生成代码，实现Android设备上的两个进程间通信(IPC)。AIDL的IPC机制和EJB所采用的CORBA很类似，进程之间的通信信息，首先会被转换成AIDL协议消息，然后发送给对方，对方收到AIDL协议消息后再转换成相应的对象。由于进程之间的通信信息需要双向转换，所以android采用代理类在背后实现了信息的双向转换，代理类由android编译器生成，对开发人员来说是透明的。

服务端:

//CalculateInterface.aidl
package com.itheima.aidl.calculate;
interface CalculateInterface {
double doCalculate(double a, double b);
}
//CalculateService.java
package com.itheima.myaidl.server;
import com.itheima.aidl.calculate.CalculateInterface;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
public class CalculateService extends Service{
private final CalculateInterface.Stub mBinder = new CalculateInterface.Stub() {
@Override
public double doCalculate(double a, double b) throws RemoteException {
return a+b;
}
};
@Override
public IBinder onBind(Intent intent) {
Log.i("test","onBind...");
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("test","onUnbind...");
return super.onUnbind(intent);
}
@Override
public void onCreate() {
super.onCreate();
Log.i("test","onCreate...");
}
@Override
public void onDestroy() {
super.onDestroy();
Log.i("test","onDestroy...");
}
}
//服务端manifast文件
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.itheima.myaidl.server"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity 
android:name="com.itheima.myaidl.server.MainActivity"
android:configChanges="locale|layoutDirection"
android:theme="@android:style/Theme.Light.NoTitleBar"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name="com.itheima.myaidl.server.CalculateService">
<intent-filter>
<action android:name="com.itheima.myaidl.server.CalculateService" />
</intent-filter>
</service>
</application>
</manifest>
//客户端
//MainActivity.java
package com.itheima.myaidl.client;
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 com.itheima.aidl.calculate.CalculateInterface;
public class MainActivity extends Activity {
private CalculateInterface mService;
private ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
Log.i("test","service disconnected...");
mService = null;
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.i("test","service connected...");
mService = CalculateInterface.Stub.asInterface(service); //获取接口实例
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//绑定远程服务
Bundle bundle = new Bundle();
Intent intent = new Intent();
intent.putExtras(bundle);
intent.setAction("com.itheima.myaidl.server.CalculateService");
bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE);
}
//TODO activity加载完毕时回调此方法
@Override
public void onWindowFocusChanged(boolean hasFocus) {
if(hasFocus){
try{
double result = mService.doCalculate(1, 2);
Log.i("test","result===>"+result);
}catch(RemoteException e){
e.printStackTrace();
}
}
super.onWindowFocusChanged(hasFocus);
}
@Override
protected void onDestroy() {
unbindService(mServiceConnection); //解绑远程服务
super.onDestroy();
}
}

运行结果截图:

以上所述是小编给大家介绍的Android中如何利用AIDL机制调用远程服务的相关知识，希望对大家有所帮助！