关于Android 添加系统级(java)服务和调用的编写实现说明

          关于Android 添加系统级(java)服务和调用的编写实现说明：本文当主要描述Android添加java 系统级服务的编写实现。一.添加java 系统级服务：      目前网站上介绍的比较多，但是没有很详细的步骤和流程。现总结如下：以 AlarmManagerService为例Java层服务顾名思义即为从 Java层提供的服务，它与 C++层的服务不同之处在于其服务进程的运行由系统（ ServiceManager）统一维护。在文件 frameworks /base /services /java /com /android /server /SystemServer.java 中我们可以看到以下代码：AlarmManagerService alarm = new AlarmManagerService (context );ServiceManager .addService (Context .ALARM_SERVICE , alarm );         这个操作在系统启动时完成，由 ServiceManager 负责创建服务进程并运行之。        在目录/frameworks/base/core/java中IAlarmManager.aidl文件.在目录frameworks/base/services/java/com/android/server中AlarmManagerService的aidl的实现类，在目录frameworks/base/services/java/com/android/server增加 service的实现文件.二.实验测试添加java 系统级服务步骤：      1.增加aidl文件在目录/frameworks/base/core/java/android/app下增加中IDvbService.aidl.package android.app;interface IDvbService {int countTest(in int testvalue);}2.在目录frameworks/base/services/java/com/android/server中增加DvbManagerService实现IDvbService.aidl类package com.android.server;import android.content.Context;import android.util.Slog;import android.app.IDvbService;class DvbManagerService extends IDvbService.Stub {     private static final String TAG = "DvbManagerService";    private static final boolean localLOGV = false;    private final Context mContext;        public DvbManagerService(Context context) {        super();        mContext = context;        Slog.w(TAG, "DvbManagerService");    }        public int countTest(int value){    return value*2;    }    }      3.在文件 frameworks /base /services /java /com /android /server /SystemServer.java 类中run（）方法中增加 Slog.i(TAG, "Alarm DvbManagerService");            DvbManagerService dvb = new DvbManagerService(context);//dvb            Slog.i(TAG, "Alarm DvbManagerService dvb ="+dvb);            ServiceManager.addService(Context.DVB_SERVICE, dvb); 4.在文件/frameworks/base/core/java/android/content/Context.java中增加public static final String DVB_SERVICE = "dvb";//dvb5.在文件/frameworks/base/core/java/android/app中增加DvbManager.javapackage android.app;import android.content.Context;import android.content.Intent;import android.os.RemoteException;import android.os.ServiceManager;public class DvbManager{//dvb    private final IDvbService mService;    /**     * package private on purpose     */    DvbManager(IDvbService service) {        mService = service;    }        public int count(int value) {        try {        return mService.countTest(value);        } catch (RemoteException ex) {        }        return -1;    }    }6.在文件/frameworks/base/core/java/android/app/ContextImpl.java中新增加属性    private static DvbManager sDvbManager;//dvb在getSystemService(String name)方中增加else if (DVB_SERVICE.equals(name)) {//dvb        return getDvbManager();    } 另外增加方法    private DvbManager getDvbManager() {//dvb    Log.e(TAG, "getDvbManager sSync = "+sSync);    Log.e(TAG, "getDvbManager sDvbManager = "+sDvbManager);        synchronized (sSync) {            if (sDvbManager == null) {                IBinder b = ServiceManager.getService(DVB_SERVICE);            Log.e(TAG, "getDvbManager IBinder = "+b);                IDvbService service = IDvbService.Stub.asInterface(b);            Log.e(TAG, "getDvbManager IDvbService = "+service);                sDvbManager = new DvbManager(service);            }        }        return sDvbManager;    }7.在/frameworks/base/Android.mk中LOCAL_SRC_FILES += \下增加core/java/android/app/IDvbService.aidl \8.在应用调用如下：导入import android.app.DvbManager; 用法     DvbManager dvb=(DvbManager)getSystemService(DVB_SERVICE);        int count = dvb.count(9);        Toast.makeText(        TVMainActivity.this,"dvb.count(9)  back = "+count,                Toast.LENGTH_SHORT).show();9.编译如下:（1）首先编译 frameworks. build/envsetup.sh choosecombo make -j4  framework编译后会生成framework.jar（2）然后编译frameworks/base/services/java的servicemake -j4  frameworks/base/services/java编译后会生成services.jar（3）编译应用因为服务是自定义的，所有必须在自定义的sdk中编译才能使用。