code: protected void monitorDir(String directory,IOFileFilter filter) throws Exception
  	{
  		FileAlterationObserver observer=new FileAlterationObserver(directory,filter);
  		observer.initialize();
  		observer.addListener(fileListener);
  		observers.add(observer);
  	}
docs: 监视目录
  @param directory
  @param filter
  @throws Exception