在android平臺中，一個進程通常不能訪問其他進程中的內存區域的。但是，我們可以使用IDL語言來把對象僞裝成操作系統能理解的簡單形式，以便僞裝成對象跨越邊界訪問。
如果想在應用程序中調用其他進程中的Service，則需要用到AIDL，AIDL(android接口描述語言)是一種IDL語言，它可以生成一段代碼，可以使在一個android設備上運行的兩個進程使用內部通信進程進行交互。如果你需要在一個進程中(例如:在一個Activity中)訪問另一個進程中(例如:一個Service)某個對象的方法,你就可以使用AIDL來生成這樣的代碼來僞裝傳遞各種參數。
使用AIDL的方法如下：
1.首先要編寫一個IMusicService.aidl的服務接口，ADT會根據這個接口文件幫我們自動生成一個 Stub類，這個類繼承了Binder類，同時繼承了IMusicService這個接口，還可以看到其中包含了一個Proxy代理類，以實現遠程代理，訪問不同的進程。(aidl和Stub類如下所示)。
/**
* IMusicService.aidl
* com.androidtest.service.mediaplayer
*
* Function： TODO
*
* ver date author
* ──────────────────────────────────
* 2011-5-19 Leon
*
* Copyright (c) 2011, TNT All Rights Reserved.
*/
package com.zuiniuwang.service;
/**
* ClassName:IMusicService
* Function: TODO ADD FUNCTION
* Reason: TODO ADD REASON
*
* @author Leon
* @version
* @since Ver 1.1
* @Date 2011-5-19
*/
interface IMusicService{
void play();
void pause();
void stop();
}
/*
* This file is auto-generated. DO NOT MODIFY.
* Original file: E:\\myworkspace\\musicservice4\\src\\com\\zuiniuwang\\service\\IMusicService.aidl
*/
package com.zuiniuwang.service;
/**
* ClassName:IMusicService
* Function: TODO ADD FUNCTION
* Reason: TODO ADD REASON
*
* @author Leon
* @version
* @since Ver 1.1
* @Date 2011-5-19
*/
public interface IMusicService extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements com.zuiniuwang.service.IMusicService
{
private static final java.lang.String DESCRIPTOR = "com.zuiniuwang.service.IMusicService";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
* Cast an IBinder object into an com.zuiniuwang.service.IMusicService interface,
* generating a proxy if needed.
*/
public static com.zuiniuwang.service.IMusicService asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = (android.os.IInterface)obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof com.zuiniuwang.service.IMusicService))) {
return ((com.zuiniuwang.service.IMusicService)iin);
}
return new com.zuiniuwang.service.IMusicService.Stub.Proxy(obj);
}
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_play:
{
data.enforceInterface(DESCRIPTOR);
this.play();
reply.writeNoException();
return true;
}
case TRANSACTION_pause:
{
data.enforceInterface(DESCRIPTOR);
this.pause();
reply.writeNoException();
return true;
}
case TRANSACTION_stop:
{
data.enforceInterface(DESCRIPTOR);
this.stop();
reply.writeNoException();
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements com.zuiniuwang.service.IMusicService
{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
{
mRemote = remote;
}
public android.os.IBinder asBinder()
{
return mRemote;
}
public java.lang.String getInterfaceDescriptor()
{
return DESCRIPTOR;
}
public void play() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_play, _data, _reply, 0);
_reply.readException();
}
finally {
_reply.recycle();
_data.recycle();
}
}
public void pause() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_pause, _data, _reply, 0);
_reply.readException();
}
finally {
_reply.recycle();
_data.recycle();
}
}
public void stop() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_stop, _data, _reply, 0);
_reply.readException();
}
finally {
_reply.recycle();
_data.recycle();
}
}
}
static final int TRANSACTION_play = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
static final int TRANSACTION_pause = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
static final int TRANSACTION_stop = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);
}
public void play() throws android.os.RemoteException;
public void pause() throws android.os.RemoteException;
public void stop() throws android.os.RemoteException;
}
3. 在Activity中得到Binder的方式，是通過Stub類的IMusicService.Stub.asInterface(binder)方法（這一點和以前不同）。相應的代碼如下：
/**
* RemoteMusicPlayerActivity.java
* com.androidtest.activity.musicplayer
*
* Function： TODO
*
* ver date author
* ──────────────────────────────────
* 2011-5-20 Leon
*
* Copyright (c) 2011, TNT All Rights Reserved.
*/
package com.zuiniuwang.playeractivity;
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.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import com.zuiniuwang.R;
import com.zuiniuwang.service.IMusicService;
/**
* ClassName:RemoteMusicPlayerActivity Function: TODO ADD FUNCTION Reason: TODO
* ADD REASON
*
* @author Leon
* @version
* @since Ver 1.1
* @Date 2011-5-20
*/
public class RemoteMusicPlayerActivity extends Activity implements
OnClickListener {
private static final String TAG = RemoteMusicPlayerActivity.class
.getSimpleName();
private Button playButton, pauseButton, stopButton, closeActivityButton,
exitActivityButton;
private IMusicService musicServiceInterface;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
this.setContentView(R.layout.music_player_layout);
findViews();
bindViews();
connection();
}
private void findViews() {
playButton = (Button) this.findViewById(R.id.play);
pauseButton = (Button) this.findViewById(R.id.pause);
stopButton = (Button) this.findViewById(R.id.stop);
closeActivityButton = (Button) this.findViewById(R.id.close);
exitActivityButton = (Button) this.findViewById(R.id.exit);
}
private void bindViews() {
playButton.setOnClickListener(this);
pauseButton.setOnClickListener(this);
stopButton.setOnClickListener(this);
closeActivityButton.setOnClickListener(this);
exitActivityButton.setOnClickListener(this);
}
private void connection() {
Intent intent = new Intent(
"com.androidtest.service.mediaplayer.RemoteMusicService");
this.startService(intent);
this.bindService(intent, myServiceConnection, Context.BIND_AUTO_CREATE);
}
private ServiceConnection myServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder binder) {
musicServiceInterface = IMusicService.Stub.asInterface(binder);
Log.d(TAG, " onServiceConnected");
}
@Override
public void onServiceDisconnected(ComponentName name) {
musicServiceInterface = null;
Log.d(TAG, " onServiceDisconnected");
}
};
@Override
public void onClick(View view) {
// TODO Auto-generated method stub
try {
switch (view.getId()) {
case R.id.play:
Log.d(TAG, "play.......");
musicServiceInterface.play();
break;
case R.id.pause:
Log.d(TAG, "pause.......");
musicServiceInterface.pause();
break;
case R.id.stop:
Log.d(TAG, "stop.......");
musicServiceInterface.stop();
break;
case R.id.close:
//Activity退出之前要解除綁定，不然會報錯
this.unbindService(myServiceConnection);
Log.d(TAG, "close.......");
this.finish();
break;
case R.id.exit:
Log.d(TAG, "exit.......");
this.unbindService(myServiceConnection);
this.stopService(new Intent("com.androidtest.service.mediaplayer.RemoteMusicService"));
this.finish();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
4. 最後在此Service註冊的時候我們需要指定它是在一個不同的進程中運行的，本例子指定的是remote進程。注意 process參數。
<!-- 註冊Service -->
<service android:enabled="true"
android:name=".service.RemoteMusicService" android:process=":remote">
<intent-filter>
<action android:name="com.androidtest.service.mediaplayer.RemoteMusicService" />
</intent-filter>
</service>有問題可以發表評論或者微博私信我。
