public  static UserInfo checkLogin(int jkNum,String pwd){
		UserInfo user=userDB.get(jkNum);
		if(null!=user&&user.getPwd().equals(pwd)){
			LogTools.INFO(UserDao.class, "½ɹ jkNum:"+jkNum);
			return user;
		}
		 LogTools.ERROR(UserDao.class, "½ʧ jkNum:"+jkNum);
		return null;
	}