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：/article/9380474.html