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);    }  @Overridepublic 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