public void driver(UserDataService userData) {
   UserPO user1 = new UserPO("100000001", UserType.DELIVERY, "Feifei", 1, "0011001", "abc123");
   UserPO user2 = new UserPO("000000001", UserType.ADMINISTRATOR, "Shiny", 5, "", "admin");
   if (userData.add(user1).equals(ResultMessage.SUCCEED)) {
     System.out.println("add succeed");
   }
   if (userData.add(user2).equals(ResultMessage.SUCCEED)) {
     System.out.println("add succeed");
   }
   if (userData.add(user1).equals(ResultMessage.EXITED)) {
     System.out.println("add failed,car exited");
   }
   UserPO get = userData.find("100000001");
   if (get != null)
     System.out.println("find:name=" + get.getUserName() + ",password="******"100000002");
   if (get == null) System.out.println("find failed,not found");
   user1.setUserId("100000002");
   if (userData.modify(user1).equals(ResultMessage.SUCCEED)) System.out.println("modify succeed");
   if (userData.delete("100000002").equals(ResultMessage.SUCCEED))
     System.out.println("delete succeed");
   if (userData.delete("100000002").equals(ResultMessage.NOTFOUND))
     System.out.println("delete failed,not found");
 }