Android停止服务问题

Question

我正在使用服务从JSON API下载一些数据。但是我试图阻止它的方式实际上并没有真正发挥作用，而且我不确定为什么。以下是MyService.class中的内容：

public class MyService extends Service{

Thread myThread;
Handler myHandler = new Handler();
public static boolean state = false;
PowerManager.WakeLock wl ;
PowerManager pm;
boolean wakeUpFlag = false;

public class LocalBinder extends Binder {
    public MyService getService() {
        return MyService.this;
    }
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

public Runnable myRunnableProgress = new Runnable() {
    public void run() { 
        state = false;
        stopSelf();
        if(wakeUpFlag){
            wl.release();
            System.out.println("Released the wakelock");
        }
    }
};

@Override
public void onCreate(){
    if (RPCCommunicator.chkNetworkStatus()) {

        myThread =  new Thread(new Runnable() {
            public void run() {
                    downloadGenres();
                    downloadCollections();
                    downloadTutorials();
                    downloadNotices();
                    myHandler.post(myRunnableProgress);
            }
        });
        myThread.start();
    }
}

@Override
public void onDestroy(){        
    super.onDestroy();

    Intent intent = new Intent("finish");
    this.sendBroadcast(intent);
}

@Override
public void onStart(Intent intent, int startid) {
    super.onStart(intent, startid);
    wakeUpFlag = false;
    pm = (PowerManager)getSystemService(Context.POWER_SERVICE);


    if(pm.isScreenOn()) {
        wakeUpFlag  = true;
        wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ON_AFTER_RELEASE,"boom");
        Log.e("","Screen off - wake lock acquired");
        wl.acquire();
    }
    else{
        Log.e("","Screen on - no need of wake lock");
    }
}

//Download genres
public void downloadGenres(){
    JsonGenre jsonGenres = new JsonGenre();
    jsonGenres.executeInsert(this); 
}

//Download collections
public void downloadCollections(){
    JsonCollection jsonColl = new JsonCollection();
    jsonColl.executeInsert(MyService.this); 
}

//Download tutorial
public void downloadTutorials(){
    JsonContent jsonContent = new JsonContent();
    jsonContent.executeInsert(this);
}

//Download Notices
public void downloadNotices(){
    JsonNews jsonNews = new JsonNews();
    jsonNews.executeInsert(this);
}

}

以下是我在我的活动（onClickListener）中启动服务的方式：

getApplicationContext().startService(new Intent(MyCollectionList.this,MyService.class));

有什么建议吗？