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();

									}

									}