public static String regin(List<User> userList) throws IOException{
		File mfile = new File("user.dat");	
		if(!mfile.exists()) return "޼¼";
		
		User user = null;
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream(mfile));		
		try{
			while((user=(User)ois.readObject())!=null){
				userList.add(user);
			}
		}catch(EOFException e){
			System.out.println("ļȡ");
		} catch (ClassNotFoundException e) {
			System.out.println("ʽ");
			e.printStackTrace();
		}
		ois.close();
		return "ѯ";
	}