这个demo的功能很简单,就是输出一句log.这篇文章只是讲了下添加系统服务的具体操作,没有讲原理,后面不出意外的话应该会写一篇文章专门讲这个,希望不会鸽.
首先说明添加系统服务一共分为两步: 1.自定义系统服务(HelloService), 2. 注册系统服务.
1. 自定义系统服务HelloService
文件位置：frameworks/base/core/java/android/app
- 添加 HelloServiceManager.java
- 添加 IHelloServiceManager.aidl (可以不加,主要是为了生成3)
- 添加 IHelloServiceManager.java( aidl + 2 自动生成)
- 添加 HelloService.java（文件位置frameworks/base/services/core/java/com/android/server/）
HelloServiceManager.java
package android.app;
import android.os.RemoteException;
import android.annotation.SystemService;
import android.content.Context;
@SystemService(Context.HELLO_SERVICE)
public final class HelloServiceManager{
private final IHelloServiceManager mService;
private Context mContext;
/**
* @hide to prevent subclassing from outside of the framework
*/
HelloServiceManager(Context context,IHelloServiceManager service){
mContext = context;
mService = service;
}
public void printHello(){
try{
mService.printHello();
}catch (RemoteException ex){
}
}
IHelloServiceManager.aidl (这个可以利用AS自动生成IHelloServiceManager.java,然后直接添加java文件就行,不用再添加aidl)
package android.app;
/**
* System private API for talking with the helloworld service.
* {@hide}
*/
interface IHelloServiceManager{
void printHello();
}
HelloService.java(注意该文件添加位置与前两个不同).
package com.android.server;
import android.app.IHelloWorldManager;
import android.content.Context;
import android.os.RemoteException;
import android.util.Slog;
import android.content.Context;
import com.android.server.SystemService;
public class HelloService extends IHelloServiceManager.Stub {
private final static String LOG_TAG = "HelloService";
private final Object mLock = new Object();
private final Context mContext;
HelloService(Context context) {
mContext = context;
}
@Override
public void printHello() throws RemoteException {
Slog.i(LOG_TAG,"Hello,World!");
}
}
一个自定义的service就完成了.
2. 注册Service
修改：
frameworks/base/core/java/android/app/SystemServiceRegistry.java
frameworks/base/core/java/android/content/Context.java
frameworks/base/services/java/com/android/server/SystemServer.java
SystemServiceRegistry.java //以下代码放在static块即可
registerService(Context.HELLO_SERVICE, HelloServiceManager.class,
new CachedServiceFetcher<HelloServiceManager>() {
@Override
public HelloServiceManager createService(ContextImpl ctx) throws ServiceNotFoundException {
IBinder binder;
if (true){//ctx.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.O) {
binder = ServiceManager.getServiceOrThrow(Context.HELLO_SERVICE);
} else {
binder = ServiceManager.getService(Context.HELLO_SERVICE);
}
return new HelloServiceManager(ctx,IHelloServiceManager.Stub.asInterface(binder));
}});
Context.java(仿照其他service添加)
主要有两处,一处定义HELLO_SERVICE, 另一处StringDef块里.
ACCOUNT_SERVICE,
ACTIVITY_SERVICE,
ALARM_SERVICE,
+ HELLO_SERVICE,
NOTIFICATION_SERVICE,
ACCESSIBILITY_SERVICE,
CAPTIONING_SERVICE,
...
public static final String HELLO_SERVICE = "hello";
SystemServer.java
在startBootstrapServices()函数中添加,启动最早,也可以在startCoreServices()或者startOtherServices()中添加.
private static final String HELLO_SERVICE = "com.android.server.HelloService";
...
//startBootstrapServices()函数中添加
if(true){
HelloService helloservice = null;
try{
traceBeginAndSlog("HelloService");
helloservice = new HelloService(mSystemContext);
ServiceManager.addService(Context.HELLO_SERVICE,helloservice);
}catch(Throwable e){
Slog.e(TAG, "Starting HelloService failed!!! ", e);
}
traceEnd();
}
以上就是添加系统服务的全部代码.
3 编译源码 及 验证
编译只需要两个命令.(在source build/envsetup.sh 以及 lunch 后) 首先make update-api 然后再make即可.
写一个app然后调用
HelloService hs = (HelloService) getSystemService(Context.HELLO_SERVICE);
hs.printhello();
如果不出意外的话AS会报错,因为SDK里面没有HelloService 和 Context.HELLO_SERVICE这写东西. 但其实系统是有的,只是编译器不知道罢了, 所以骗过AS就好, 把上面的两行代码用反射实验就好.
最后 点个赞吧. 关注下就更好了. 谢谢!
参考文章
android添加service
