關於Android 添加系統級(java)服務和調用的編寫實現說明

          關於Android 添加系統級(java)服務和調用的編寫實現說明：本文當主要描述Android添加java 系統級服務的編寫實現。一.添加java 系統級服務：      目前網站上介紹的比較多，但是沒有很詳細的步驟和流程。現總結如下：以 AlarmManagerService為例Java層服務顧名思義即為從 Java層提供的服務，它與 C++層的服務不同之處在於其服務進程的運行由系統（ ServiceManager）統一維護。在檔案 frameworks /base /services /java /com /android /server /SystemServer.java 中我們可以看到以下代碼：AlarmManagerService alarm = new AlarmManagerService (context );ServiceManager .addService (Context .ALARM_SERVICE , alarm );         這個操作在系統啟動時完成，由 ServiceManager 負責建立服務進程並運行之。        在目錄/frameworks/base/core/java中IAlarmManager.aidl檔案.在目錄frameworks/base/services/java/com/android/server中AlarmManagerService的aidl的實作類別，在目錄frameworks/base/services/java/com/android/server增加 service的實現檔案.二.實驗測試添加java 系統級服務步驟：      1.增加aidl檔案在目錄/frameworks/base/core/java/android/app下增加中IDvbService.aidl.package android.app;interface IDvbService {int countTest(in int testvalue);}2.在目錄frameworks/base/services/java/com/android/server中增加DvbManagerService實現IDvbService.aidl類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.在檔案 frameworks /base /services /java /com /android /server /SystemServer.java 類中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.在檔案/frameworks/base/core/java/android/content/Context.java中增加public static final String DVB_SERVICE = "dvb";//dvb5.在檔案/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.在檔案/frameworks/base/core/java/android/app/ContextImpl.java中新增加屬性    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.在應用調用如下：匯入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.編譯如下:（1）首先編譯 frameworks. build/envsetup.sh choosecombo make -j4  framework編譯後會產生framework.jar（2）然後編譯frameworks/base/services/java的servicemake -j4  frameworks/base/services/java編譯後會產生services.jar（3）編譯應用因為服務是自訂的，所有必須在自訂的sdk中編譯才能使用。