如何在Android中添加系统服务

这里说的系统服务，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：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

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

四、在ContextImpl getSystemService中添加代码

五、测试代码

/system/bin/screencap u:object_r:screencap_exec:s0

type screencap, domain,coredomain

type screencap_exec, exec_type,vendor_file_type,file_type

init_daemon_domain(screencap)

SystemProperties.set("ctl.start*", "xxx")，即可

1.添加.AIDL文件

/frameworks/base/core/java/android/os/IHelloService.aidl

[java] view plain copy

package android.os

interface IHelloService

{

String test_service(String input)

}

在/frameworks/base/Android.mk 把aidl文件加入到源码编译器中

[java] view plain copy

core/java/android/os/IHelloService.aidl \

2.编写服务类

/frameworks/base/services/java/com/android/server/HelloService.java

[java] view plain copy

package com.android.server

import android.os.IHelloService

import android.os.IBinder

import android.content.Context

import android.util.Log

public class HelloService extends IHelloService.Stub

{

private static final String TAG="HelloService"

@Override

public String test_service(String input){

Log.i(TAG,"eva HelloService HelloService,test_service()) method")

return input

}

public HelloService()

{

super()

Log.i(TAG,"eva HelloService Constructor method")

}

}

3.编写服务管理器

/frameworks/base/core/java/android/os/TestServiceManager/frameworks/base/core/java/android/os/HelloManager.java

[java] view plain copy

package android.os

import android.os.IHelloService

import android.content.Context

import android.os.RemoteException

import android.util.Log

public class HelloManager

{

//Basic Member

android.os.IHelloService mService

private static final String TAG="HelloManager"

//Constructor

public HelloManager(Context ctx,android.os.IHelloService service)

{

mService=service

Log.i(TAG,"eva HelloManager Constructor method")

}

public String test_service(String input){

try{

Log.i(TAG,"eva HelloManager Constructor mService.test_service")

return mService.test_service(input)

}catch(RemoteException e)

{

return e.getMessage()

}

}

}

4.注册服务

/frameworks/base/core/java/android/app/SystemServiceRegistry.java

[java] view plain copy

import android.os.IHelloService

import android.os.HelloManager

registerService("HELLO_SERVICE",HelloManager.class,

new CachedServiceFetcher<HelloManager>(){

@Override

public HelloManager createService(ContextImpl ctx)

{

IBinder b = ServiceManager.getService("HELLO_SERVICE")

Log.i(TAG,"eva SystemServiceRegistry registerService method")

return new HelloManager(ctx,IHelloService.Stub.asInterface(b))

}})

5.启动服务

/frameworks/base/services/java/com/android/server/SystemServer.java

[java] view plain copy

import com.android.server.HelloService

ServiceManager.addService("HELLO_SERVICE", new HelloService())

6.将服务加入到源码中，编译备份

/external/sepolicy/service.te

[java] view plain copy

type hello_service, system_api_service, system_server_service, service_manager_type

7.给服务权限

/external/sepolicy/service_contexts

[java] view plain copy

HELLO_SERVICE u:object_r:hello_service:s0

8.Demo

MainActivity.java

[java] view plain copy

package com.example.testservicedemo

import android.app.Activity

import android.os.Bundle

import android.view.View

import android.view.View.OnClickListener

import android.widget.Button

import android.widget.EditText

import android.widget.TextView

import android.os.HelloManager

public class MainActivity extends Activity {

private EditText writeEdit

private Button readBtn

private TextView showInfo

private HelloManager mTestServiceManager

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState)

setContentView(R.layout.activity_main)

writeEdit = (EditText)findViewById(R.id.input)

readBtn = (Button)findViewById(R.id.read)

showInfo = (TextView)findViewById(R.id.showinfo)

mTestServiceManager = (HelloManager)getSystemService("HELLO_SERVICE")

readBtn.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

String inputString = writeEdit.getText().toString()

String result = mTestServiceManager.test_service(inputString)

showInfo.setText(result)

}

})

}

}

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