You can use username registration to analyze three actions to obtain data, and three actions.
1. Inject attributes
Directly inject attributes:
1 public String userName; 2 3 4 public String getUserName () {5 return userName; 6} 7 8 9 public void setUserName (String userName) {10 this. userName = userName; 11} 12 13 14 @ Override15 public String execute () throws Exception {16 // TODO Auto-generated method stub17 18 User user = new User (); 19 user. setUserName (userName); // here you need to receive and use username. 20 UserDAO dao = new UserDAO (); 21 HttpServletResponse response = ServletActionContext. getResponse (); 22 PrintWriter out = response. getWriter (); 23 if (dao. checkExists (user) 24 {25 out. print ("1"); 26} 27 else28 {29 out. print ("0"); 30} 31 return null; 32}
2. Domain Model this is a common method
This is not repeated here,
3. ModelDriven
The third method is not commonly used. You only need to understand it;
The process is divided into four steps:
(1) Implement the ModelDriven <User> interface for action
(2) Add Abstract METHODS
(3) Define and initialize a model
User user = new User ();
(4) generate setter and getter
1 public class CheckUserAction extends ActionSupport implements ModelDriven<User>{ 2 private User user = new User(); 3 public User getUser() { 4 return user; 5 } 6 7 public void setUser(User user) { 8 this.user = user; 9 }10 11 @Override12 public String execute() throws Exception {13 // TODO Auto-generated method stub14 15 16 UserDAO dao = new UserDAO();17 HttpServletResponse response= ServletActionContext.getResponse();18 PrintWriter out = response.getWriter();19 if(dao.checkExists(user))20 {21 out.print("1");22 }23 else24 {25 out.print("0");26 }27 return null;28 }29 30 @Override31 public User getModel() {32 // TODO Auto-generated method stub33 return user;34 }35
Note: you do not need to change the front-end and jsp code when using methods 1 and 3, because the userName attribute is directly called.
Method 2: Change username in jquery to user. username.