MiNotes/src/zhushi/micode/notes/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.
 */

package net.micode.notes.gtask.remote;

import android.app.Activity;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;

/**
 * Google Tasks同步服务类
 * 负责管理与Google Tasks的同步操作,包括启动同步、取消同步等功能
 */
public class GTaskSyncService extends Service {
    /** Intent中同步动作的键名 */
    public final static String ACTION_STRING_NAME = "sync_action_type";

    /** 开始同步的动作值 */
    public final static int ACTION_START_SYNC = 0;

    /** 取消同步的动作值 */
    public final static int ACTION_CANCEL_SYNC = 1;

    /** 无效动作值 */
    public final static int ACTION_INVALID = 2;

    /** 广播Action名称 */
    public final static String GTASK_SERVICE_BROADCAST_NAME = "net.micode.notes.gtask.remote.gtask_sync_service";

    /** 广播Extra:是否正在同步 */
    public final static String GTASK_SERVICE_BROADCAST_IS_SYNCING = "isSyncing";

    /** 广播Extra:同步进度信息 */
    public final static String GTASK_SERVICE_BROADCAST_PROGRESS_MSG = "progressMsg";

    /** 异步同步任务实例 */
    private static GTaskASyncTask mSyncTask = null;

    /** 同步进度信息 */
    private static String mSyncProgress = "";

    /**
     * 启动同步操作
     * 如果当前没有正在进行的同步任务,则创建新的异步任务并执行
     */
    private void startSync() {
        if (mSyncTask == null) {
            mSyncTask = new GTaskASyncTask(this, new GTaskASyncTask.OnCompleteListener() {
                public void onComplete() {
                    mSyncTask = null;
                    sendBroadcast("");
                    stopSelf();
                }
            });
            sendBroadcast("");
            mSyncTask.execute();
        }
    }

    /**
     * 取消当前的同步操作
     */
    private void cancelSync() {
        if (mSyncTask != null) {
            mSyncTask.cancelSync();
        }
    }

    /**
     * Service创建时的回调
     * 初始化同步任务为空
     */
    @Override
    public void onCreate() {
        mSyncTask = null;
    }

    /**
     * Service启动时的回调
     * 处理同步相关的Intent请求
     * @param intent 启动服务的Intent
     * @param flags 启动标志
     * @param startId 启动ID
     * @return 粘性服务的标志
     */
    @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);
    }

    /**
     * 系统内存不足时的回调
     * 取消当前的同步任务
     */
    @Override
    public void onLowMemory() {
        if (mSyncTask != null) {
            mSyncTask.cancelSync();
        }
    }

    /**
     * 绑定Service时的回调
     * 本服务不支持绑定,返回null
     */
    public IBinder onBind(Intent intent) {
        return null;
    }

    /**
     * 发送同步状态广播
     * @param msg 同步进度信息
     */
    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
     * @param activity 当前Activity上下文
     */
    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
     * @param context 应用程序上下文
     */
    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:判断是否正在同步
     * @return 是否有正在进行的同步任务
     */
    public static boolean isSyncing() {
        return mSyncTask != null;
    }

    /**
     * 静态方法:获取当前同步进度信息
     * @return 同步进度信息字符串
     */
    public static String getProgressString() {
        return mSyncProgress;
    }
}