java/zz_code/gtask/remote/GTaskSyncService.java

/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//sync (同步)任务：主线程上排队执行的任务
//async (异步)任务：不进入主线程，而进入任务队列的任务
//gtask:远程任务系统

/*Service是在一段不定的时间运行在后台，不和用户交互的应用组件
        * 主要方法：
        * private void startSync()  启动一个同步工作
        * private void cancelSync() 取消同步
        * public void onCreate()
        * public int onStartCommand(Intent intent, int flags, int startId)  service生命周期的组成部分，相当于重启service（比如在被暂停之后），而不是创建一个新的service
        * public void onLowMemory()  在没有内存的情况下如果存在service则结束掉这的service
        * public IBinder onBind()
        * public void sendBroadcast(String msg)   发送同步的相关通知
        * public static void startSync(Activity activity)
        * public static void cancelSync(Context context)
        * public static boolean isSyncing()  判读是否在进行同步
        * public static String getProgressString()  获取当前进度的信息
*/

package net.micode.notes.gtask.remote;

//引入工具类
import android.app.Activity;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;

//GTask同步服务类，继承自Android的Service类
public class GTaskSyncService extends Service {
    //final修饰的变量表示常量，static表示静态变量，表示这个变量是类变量，而不是实例变量,所有的实例共享这个变量
    //定义一个字符串常量，表示同步操作的类型
    public final static String ACTION_STRING_NAME = "sync_action_type";
    //标识启动同步任务的操作
    public final static int ACTION_START_SYNC = 0;
    //标识取消同步任务的操作
    public final static int ACTION_CANCEL_SYNC = 1;
    //标识无效的操作
    public final static int ACTION_INVALID = 2;
    //定义一个字符串常量，表示同步服务的广播名称
    public final static String GTASK_SERVICE_BROADCAST_NAME = "net.micode.notes.gtask.remote.gtask_sync_service";
    //定义一个字符串常量，表示是否正在同步的广播名称
    public final static String GTASK_SERVICE_BROADCAST_IS_SYNCING = "isSyncing";
    //定义一个字符串常量，表示同步进度的广播名称
    public final static String GTASK_SERVICE_BROAD  CAST_PROGRESS_MSG = "progressMsg";
    //定义一个GTaskASyncTask对象
    private static GTaskASyncTask mSyncTask = null;
    //定义一个字符串变量，表示同步进度
    private static String mSyncProgress = "";

    //定义方法：启动同步任务
    private void startSync() {
        if (mSyncTask == null) {
            mSyncTask = new GTaskASyncTask(this, new GTaskASyncTask.OnCompleteListener() {
                public void onComplete() {
                    mSyncTask = null;
                    sendBroadcast("");
                    stopSelf();
                }
            });
            sendBroadcast("");
            mSyncTask.execute();
        }
    }

    //定义方法：取消同步任务
    private void cancelSync() {
        if (mSyncTask != null) {
            mSyncTask.cancelSync();
        }
    }

    //重写方法：创建服务
    @Override
    public void onCreate() {
        mSyncTask = null;
    }

    //重写方法：Service 启动时的回调方法
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Bundle bundle = intent.getExtras();
        if (bundle != null && bundle.containsKey(ACTION_STRING_NAME)) {
            switch (bundle.getInt(ACTION_STRING_NAME, ACTION_INVALID)) {
                case ACTION_START_SYNC:
                    startSync();
                    break;
                case ACTION_CANCEL_SYNC:
                    cancelSync();
                    break;
                default:
                    break;
            }
            return START_STICKY;
        }
        return super.onStartCommand(intent, flags, startId);
    }

    //重写方法：在没有内存的情况下如果存在service则结束掉这的service
    @Override
    public void onLowMemory() {
        if (mSyncTask != null) {
            mSyncTask.cancelSync();
        }
    }

    //Service 绑定时调用的方法
    public IBinder onBind(Intent intent) {
        return null;
    }

    //定义方法：广播同步的相关通知
    public void sendBroadcast(String msg) {
        mSyncProgress = msg;
        Intent intent = new Intent(GTASK_SERVICE_BROADCAST_NAME);
        intent.putExtra(GTASK_SERVICE_BROADCAST_IS_SYNCING, mSyncTask != null);
        intent.putExtra(GTASK_SERVICE_BROADCAST_PROGRESS_MSG, msg);
        sendBroadcast(intent);
    }

    //静态方法：启动同步任务
    public static void startSync(Activity activity) {
        GTaskManager.getInstance().setActivityContext(activity);
        Intent intent = new Intent(activity, GTaskSyncService.class);
        intent.putExtra(GTaskSyncService.ACTION_STRING_NAME, GTaskSyncService.ACTION_START_SYNC);
        activity.startService(intent);
    }

    //静态方法：取消同步任务
    public static void cancelSync(Context context) {
        Intent intent = new Intent(context, GTaskSyncService.class);
        intent.putExtra(GTaskSyncService.ACTION_STRING_NAME, GTaskSyncService.ACTION_CANCEL_SYNC);
        context.startService(intent);
    }

    //静态方法：判读是否在进行同步
    public static boolean isSyncing() {
        return mSyncTask != null;
    }

    //静态方法：获取当前进度的信息
    public static String getProgressString() {
        return mSyncProgress;
    }
}