Spring MVC Learning Notes 8--implement simple user management (4) User Login

Spring MVC Learning notes 8--implement simple user management (4) User Login

Check and delete, login

1. login.jsp, written on the outside, and with the web-inf of the same level of directory, such as: LS webcontent; >> Meta-inf Web-inf login.jsp

The form:<form> contains two parameters, action (target) & Method (Methods). The <input> label, type (text,password,submit), name, two parameters are used.

<form action = "User/login" method = "POST" >
   username:<input type= "text" name= "username"/><br/>< C2/>password:<input type= "password" name= "password"/><br/> <input type=
   "Submit"/>
</ Form>

2. Usercontroller.java

login.jsp clicks "Submit", will visit the login method in Usercontroller: public String Login () {}
· Specify criteria for entering method
· Specify parameters to enter method
· Exception handling 1: User name does not exist, exception handling 2: Incorrect password
· Save user to session ". 】

·

The @RequestMapping (value = "/login", method = Requestmethod.post)//requestmapping is the public String login that specifies how to enter this approach
	( String Username, string password, HttpSession session) {	//pass 2 arguments in, 1st:username 2nd:password
// The 3rd parameter is the
		if (!users.containskey (username)) {	//exception handling 1 specified session injection. If not, the username does not exist
			//Create an exception handler. Java, see next "3." A class "
			throw new Userexception (" Username does not exist! ") is required to handle the exception;
			User u = users.get (username);	Gets username
		if (!u.getpassword (). Equals (password))	{//if is not equal, stating that the password is incorrect:
			throw new Userexception (" Password does not match! ");
		}
		Save user to session:
		Session.setattribute ("Loginuser", u);
		return "Redirect:/user/users";	Login success, jump to User/users
	}

3. Need a class to handle the exception

·  Create a new class:
Name:UserException.class
Superclass:java.lang.RuntimExcption
·  Add Default Version ID: Code: Private static final long serialversionuid = 1L;

· Create a constructors constructor from superclass: Right key-resources-generate constructors from superclass

 

   Package Edu.bit.model;
        public class Userexception extends RuntimeException {public
        userexception () {
	        super ();
		TODO auto-generated constructor stub
	} public

	userexception (String arg0, Throwable arg1, Boolean arg2, Boolean ARG3) {
		super (arg0, Arg1, arg2, arg3);
		TODO auto-generated constructor stub
	} public

	userexception (String arg0, Throwable arg1) {
		super (arg0, ARG1);
		TODO auto-generated constructor stub
	} public

	userexception (String arg0) {
		super (arg0);
		TODO auto-generated constructor stub
	} public

	userexception (Throwable arg0) {
		super (arg0);
		TODO auto-generated constructor stub
	}

========== so far, the basic completion of a login operation, but if the user name does not exist or the password is incorrect, will return 500 error, and press Userexception ("error Prompt") Prompts the error ========

Test Link: http://localhost:8080/myhello/login.jsp
500 error Page Screenshot:

Implement simple user Management (4.2) User Login--Display local exception information Part Two: Display local exception information instead of 500 error page

1. Write a method to pass the userexception in.
2. Mapping method: @ExceptionHandler (), the value in brackets is Userexception.class
3. To enter the Userexception method: (userexception UE, HttpServletRequest req)
-----//1. Pass the userexception in;
-----//2. Can not use model to pass the value, because not requestmapping, with httpseverletrequest req
4. The exception object is deposited into the Httpseverletrequest req e parameter: Req.setattribute ("E", UE);
5. Return view Error:return error;

----Implementation Code-----
Usercontroller.java Add:

	
	 * * Display local exception information: Only can handle the exception in this controller
	 * Write a method, handlerexception, send userexception into the * * *
	@ExceptionHandler ( Value={userexception.class})	///Exceptionhandler to be mapped, the value to be processed is an array
							//To process an object so written, can handle multiple objects. Public
	String handlerexception (userexception UE, HttpServletRequest req) {	
				//1. Pass userexception in;
				2. Can not use model to pass the value, because is not requestmapping, with httpseverletrequest req
		//The exception object UE deposit in:
		req.setattribute ("E", UE);	Req "E" parameter, is set for uexception return
		"error";
	}

/web-inf/error.jsp code: ${e.message} FETCH message information:

<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
    pageencoding=" UTF-8 "%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "Http://www.w3.org/TR/html4/loose.dtd" >