在Android系统中实现AIDL功能

   之前实现AIDL的功能都是通过eclipse或者android studio工具实现，最近由于项目需要，需要系统层提供接口给应用层使用，所以想到使用AIDL。下面已一个非常简单的Demo来说明在Android系统平台生成AIDL的jar供应用层使用。

一、AIDL的jar制作

首先新建一个android项目来用生产aidl的jar包，项目结构如下：

gunder@gunder:/mnt/hgfs/ubuntuShare/aidl/SimpleJar$ tree
.
├── Android.mk
└── src
    └── com
        └── china
            └── jar
                ├── IVoiceClientInterface.aidl
                └── VoiceManager.java

只有三个文件，首先看一下IVoiceClientInterface.aidl文件：

package com.china.jar;

interface IVoiceClientInterface{
	void face();
}

里面只有一个简单的方法face。 IVoiceClientInterface.aidl主要是服务器端来实现的，而VoiceManager.java是供客户端调用face方法使用的。VoiceManager.java具体实现如下：

package com.china.jar;

import com.china.jar.IVoiceClientInterface;

import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.os.RemoteException;
import android.util.Log;
import android.os.ServiceManager;

public class VoiceManager {
	private static final String TAG = "VoiceManager";
	private static VoiceManager mVoiceManager;
	private static IVoiceClientInterface mService = null;
	public static final String NAME = "simple_jar";
	public static final boolean DEBUG_DATA = true;
	
	private final HandlerThread mWorkThread;
	private final Handler mWorkHander;
	private static final int MSG_INIT_SERVICE = 0x01;
	
	//单例模式
	public static synchronized VoiceManager getInstance(){
		if (null == mVoiceManager){
			synchronized (VoiceManager.class) {
				if (null == mVoiceManager){
					mVoiceManager = new VoiceManager();
				}
			}
		}
		return mVoiceManager;
	}
	
	private VoiceManager(){
		mWorkThread = new HandlerThread("simple_manager");
		mWorkThread.start();
		mWorkHander = new Handler(mWorkThread.getLooper()){
			@Override
			public void handleMessage(Message msg) {
				switch (msg.what) {
				case MSG_INIT_SERVICE:
					removeMessages(MSG_INIT_SERVICE);
					
					break;

				default:
					break;
				}
			}
		};
	}
	//获取服务端注册的NAME服务并跟服务端建立连接
	private synchronized IVoiceClientInterface getService(){
		if (null == mService){
			Log.e(TAG, "IVocieService init");
			mService = IVoiceClientInterface.Stub.asInterface(ServiceManager
                    .getService(NAME));
		}
		
		if (null == mService){
			Log.e(TAG, "jar service is null");
			mWorkHander.removeMessages(MSG_INIT_SERVICE);
			mWorkHander.sendEmptyMessageDelayed(MSG_INIT_SERVICE, 100);
		}
		return mService;
	}
	
        //调用服务端的face方法，实现两个不同app之间的进程间通信
	public void face(){
		Log.d(TAG, "face");
		mService = getService();
		if (null == mService){
			Log.e(TAG, "face mService is null!");
			return ;
		}
		try{
			mService.face();
		}catch(RemoteException e){
			e.printStackTrace();
		}
	}
}

 Android.mk文件主要是用来将IVoiceClientInterface.aidl和VoiceManager.java编译成jar包，以方便在eclipse或者Android Studio中使用。

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES := $(call all-java-files-under, src)
LOCAL_JAVA_LIBRARIES := simple
LOCAL_PACKAGE_NAME := SimpleService
LOCAL_CERTIFICATE :=platform
include $(BUILD_PACKAGE)

将该项目放置到android系统的packages/apps目录单编就可以生产out/target/common/obj/JAVA_LIBRARIES/SimpleJar_intermediates/classes.jar，classes.jar就可以导入eclipse或者Android Studio中使用。

二、服务端实现AIDL中的接口demo目录结构如下：

gunder@gunder:/mnt/hgfs/ubuntuShare/aidl/SimpleJarService$ tree 
.
├── AndroidManifest.xml
├── Android.mk
├── libs
│  └── simple.jar
├── res
│  ├── drawable-hdpi
│  │  └── ic_launcher.png
│  ├── drawable-ldpi
│  ├── drawable-mdpi
│  │  └── ic_launcher.png
│  ├── drawable-xhdpi
│  │  └── ic_launcher.png
│  ├── layout
│  ├── values
│  │  ├── strings.xml
│  │  └── styles.xml
│  ├── values-v11
│  │  └── styles.xml
│  └── values-v14
│      └── styles.xml
└── src
    └── com
        └── china
            └── service
                ├── BootReceiverBroadcast.java
                ├── Logger.java
                └── SimpleService.java
 

主要实现只有5个文件：SimpleService.java、Logger.java、BootReceiverBroadcast.java、 Android.mk、 AndroidManifest.xml。SimpleService.java是实现AIDL的服务，具体实现如下：

package com.china.service;

import com.china.jar.IVoiceClientInterface;
import com.china.jar.VoiceManager;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.os.ServiceManager;

public class SimpleService extends Service{
	private static VoiceClientInterfaceImpl mBinder;
	@Override
	public IBinder onBind(Intent intent) {
		Logger.d();
		return mBinder;//跟客户端绑定
	}
	
	@Override
	public void onCreate() {
		super.onCreate();
		Logger.d();
		if (null == mBinder){
			initService();
		}
	}
	
	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		Logger.d();
		if (null == mBinder){
			initService();
		}
		return START_STICKY;
	}
	//实现AIDL的接口
	private class VoiceClientInterfaceImpl extends IVoiceClientInterface.Stub{
		@Override
		public void face() throws RemoteException {
			Logger.d("face----excute!");//客户端调用face方法时这里会执行，会打印face----excute!
		}
	}
	//初始化服务，主要是向系统注册服务
	private void initService(){
		Logger.d();
		if (null == mBinder){
			synchronized (SimpleService.class) {
				if (null == mBinder){
					try {
						mBinder = new VoiceClientInterfaceImpl();
						ServiceManager.addService(VoiceManager.NAME, mBinder);
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			}
		}
	}
}

Logger.java是打印Log的简单封装，具体如下：

package com.china.service;

import android.util.Log;

import java.util.Locale;

public class Logger {
    public static final boolean DEBUG = true;
    public static final String DEFAULT_TAG = "AIOS_";

    public Logger(){}
    public static void d(){
        if (DEBUG){
            Log.d(DEFAULT_TAG,getPrefix());
        }
    }

    public static void d(String msg){
        if (DEBUG){
            Log.d(DEFAULT_TAG,  getPrefix() + msg);
        }
    }

    public static void d(String msg, Throwable tr){
        if (DEBUG){
            Log.d(DEFAULT_TAG, getPrefix() + msg, tr);
        }
    }


    private static String getPrefix(){
        StackTraceElement stackTraceElement = Thread.currentThread().getStackTrace()[4];
        String className = stackTraceElement.getClassName();
        int classNameStartIndex = className.lastIndexOf(".") + 1;
        className = className.substring(classNameStartIndex);
        String methodName = stackTraceElement.getMethodName();
        int methodLine = stackTraceElement.getLineNumber();
        String format = "%s_%s(L:%d)";
        return String.format(Locale.CANADA, format, className, methodName, methodLine);
    }

}

BootReceiverBroadcast.java是开机完成的时候拉起 SimpleService服务，具体实现如下：

package com.china.service;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class BootReceiverBroadcast extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        Logger.d();
        Intent service = new Intent(context, SimpleService.class);//开机启动会拉起服务SimpleService
        context.startService(service);
    }
}

 Android.mk具体实现如下：

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES := $(call all-java-files-under, src)
LOCAL_PACKAGE_NAME := SimpleService
LOCAL_CERTIFICATE :=platform
LOCAL_PRIVILEGED_MODULE := false
LOCAL_DEX_PREOPT := false
LOCAL_STATIC_JAVA_LIBRARIES := simple
include $(BUILD_PACKAGE)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional 
LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES :=simple:libs/simple.jar 
include $(BUILD_MULTI_PREBUILT)
include $(call all-makefiles-under,$(LOCAL_PATH))

 这里的simple.jar是第一步中制作的classes.jar。 AndroidManifest.xml配置文件如下：

到这里服务端就实现完了。

三、客户端实现AIDL的接口调用demo目录结构如下：

gunder@gunder:/mnt/hgfs/ubuntuShare/aidl/SimpleJarClient$ tree 
.
├── AndroidManifest.xml
├── Android.mk
├── libs
│  └── simple.jar
├── res
│  ├── drawable-hdpi
│  │  └── ic_launcher.png
│  ├── drawable-ldpi
│  ├── drawable-mdpi
│  │  └── ic_launcher.png
│  ├── drawable-xhdpi
│  │  └── ic_launcher.png
│  ├── drawable-xxhdpi
│  │  └── ic_launcher.png
│  ├── layout
│  │  ├── activity_main.xml
│  │  ├── activity_tss.xml
│  │  └── test.xml
│  ├── menu
│  ├── values
│  │  ├── dimens.xml
│  │  └── strings.xml
│  ├── values-v11
│  ├── values-v14
│  └── values-w820dp
│      └── dimens.xml
└── src
    └── com
        └── example
            └── helloworld
                ├── TestVoice.java
                └── util
                    └── Logger.java

这里主要看5个文件：Logger.java、 test.xml、TestVoice.java、Android.mk、AndroidManifest.xml，其中Logger.java跟服务端代码一样的。TestVoice.java的实现也很简单，在button调用face方法，具体实现如下：

package com.example.helloworld;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;

import com.example.helloworld.util.Logger;


public class TestVoice extends Activity{
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.test);
	}
	
	public void startVoice(View view){
		Logger.d();
    }
    
    public void stopVoice(View view){
    	Logger.d();
    	com.china.jar.VoiceManager.getInstance().face();
    }
    
    public void finishVoice(View view){
    	Logger.d();
    	finish();
    }

	
	
}

test.xml布局如下：

 Android.mk实现如下：

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := $(call all-java-files-under, src)
LOCAL_STATIC_JAVA_LIBRARIES := simple
LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES := simple.jar 
#LOCAL_MODULE_TAGS :=optional
LOCAL_PACKAGE_NAME := Hello
#LOCAL_CERTIFICATE :=platform
#LOCAL_PRIVILEGED_MODULE := false
#LOCAL_DEX_PREOPT := false
include $(BUILD_PACKAGE)

AndroidManifest.xml实现如下：

到这里客户端也实现了。将服务端跟客户端的apk安装到系统就可以测试了。 

测试结果打印如下：