如何在Android中添加系统服务

说明：本次说的系统服务，是指捆绑在system_process进程中的服务。

  仔细阅读源码可以发现，在frameworks/base/services/java/com/android/server/SystemServer.java中添加了很多服务，什么熵信息、电量、wife等等服务，这些服务启动都在launcher之前，一般要继承Binder或者继承一个AIDL。下面试着来添加一个简单系统服务

一。在frameworks/base/core/java/android/os/ 增加一个aidl文件，最后用aidl工具生产一个Java文件，这样可以方便后面：

package android.os;

/**
 * Interface that allows controlling and querying YtTts connectivity.
 *
 * {@hide}
 */
interface IYtTtsService{
	/**
	 * 播放Text文字
	 */
	int speak(String text);
}

然后在修改/frameworks/base/Android.mk，在LOCAL_SRC_FILES里添加一行：core/java/android/os/IYtTtsService.aidl \

不确定补充：把AIDL文件写在这个地方似乎可以避免加@hide

二 。在frameworks/base/services/java/com/android/server/ 新建要增加的service，继承上面aidl生产的java：

package com.android.server;
import android.content.Context;
import android.os.IYtTtsService;
import android.os.RemoteException;
import android.util.Log;

public class YtTtsService  extends IYtTtsService.Stub {
	private WorkerThread mWorker;
	public YtTtsService(Context context) {  
	    super();  
	    mWorker = new WorkerThread("YtTtsServiceWorker");  
	    mWorker.start();  
		Log.i("[YT]", "In YtTtsService-->"+context);  
	  }  	
	@Override
	public int speak(String text) throws RemoteException {
		Log.i("[YT]", "In YtTtsService-->"+text);
		return 0;
	}
    private class WorkerThread extends Thread{  
    	int i = 0;
	    public WorkerThread(String name) {  
	      super(name);  
	    }  	  
	    public void run() {  
	    	while(true){
	    		i++;
	    		Log.i("[YT]", "In YtTtsService-->WorkerThread running "+i);
	    		try {
					Thread.sleep(3000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
	    	}
	    }  
	}
}

三。在 frameworks/base/services/java/com/android/server/SystemServer.java, ServerThread中run()方法中增加代码：

            try {
                Log.i("[YT]", "In SystemServer, YtTts add..");
                ServiceManager.addService("yttts", new YtTtsService(context));
            } catch (Throwable e) {
            	Log.i("[YT]", "In SystemServer, YtTts add err..");
            }

5.在/frameworks/base/core/java/cn/youngtone/tts建一个YtTtsManager类,用于管理YtTtsService ：

package cn.youngtone.tts;

import android.content.Context;
import android.os.IYtTtsService;
import android.os.RemoteException;
import android.util.Log;

public class YtTtsManager {
	IYtTtsService service;  
    
    public YtTtsManager(Context context ,IYtTtsService service) {  
         this.service = service;  
    }  
    public void speak(String text) {  
        try {
        	Log.e("[YT]" , "In YtTtsManage-->speak():"+text); 
        	service.speak(text);
        } catch (RemoteException e) {  
        	Log.e("[YT]" , "In YtTtsManage-->E:RemoteException");  
            e.printStackTrace();  
        }  
    }  
}

四。 在ContextImpl getSystemService中添加代码：

if ("yttts".equals(name)) { 

    if (mYtTtsManager == null) {  
       IBinder b = ServiceManager.getService("yttts");  
       IYtTtsService service = IYtTtsService.Stub.asInterface(b);  
       mYtTtsManager = new YtTtsManager(this, service);  
     }  
     return mYtTtsManager;
}

五。测试代码

        YtTtsManager mManager = (YtTtsManager)getSystemService("yttts");
        mManager.speak("这是一个简单的系统服务!");

END.

参考：http://blog.csdn.net/aiai373824745/article/details/7439896