public void start(){
		if(databaseSourceDriver==null){
			databaseSourceDriver = DatabaseSourceDriverFactory.getDatabaseSourceDriver(userName,passWd);
		}
		String filename = null;
		this.scanPlanList = databaseSource.getScanPlanList();
		if(scanPlanList!=null){
			for(Iterator<ScanPlan> it = scanPlanList.iterator();it.hasNext();){
				ScanPlan scanPlan = it.next();
				System.out.println("plan"+scanPlan.getId()+" "+scanPlan.getWebSite());
				filename = "D:\\WebScan\\"+scanPlan.getId()+".xml";
				DataChecker check = new DataChecker(scanPlan,filename);
				check.addObserver(this);
				Thread thread = new Thread(check);
				//thread.start();
				this.pool.execute(thread);
				logger.log(Level.INFO,"add thread to the threadpool");
				//System.out.println(filename+" "+scanPlan.getId()+" "+scanPlan.getWebSite()+" "+scanPlan.getDateTime());
			}
		}
		shutdown();
	}