Servlet login function implementation

Servlet login function implementation

(1) create a dynamic Login page

// Log on to the package com. lc; import javax. servlet. http. *; import java. io. *; public class Login extends HttpServlet {public void doGet (HttpServletRequest req, HttpServletResponse res) {// business logic try {// solves Chinese garbled res. setContentType ("text/html; charset = gbk"); PrintWriter pw = res. getWriter (); // return to the logon interface pw. println (""); Pw. println (""); Pw. println (" User Logon "); pw. println (" "); pw. println (""); Pw. println ("");} Catch (Exception ex) {ex. printStackTrace () ;}} public void doPost (HttpServletRequest req, HttpServletResponse res) {this. doGet (req, res );}}

(2) create a servlet that accepts Login

// Log on to the package com. lc; import javax. servlet. http. *; import java. io. *; public class Logincl extends HttpServlet {public void doGet (HttpServletRequest req, HttpServletResponse res) {// business logic try {// solve Chinese garbled characters // accept username and password String u = req. getParameter ("username"); String p = req. getParameter ("passwd"); // verify if (u. equals ("lc") & p. equals ("123") {// jump to Welcomeres. sendRedirect ("welcome"); // The servlet url is redirected here} else {// illegal // redirect res. sendRedirect ("login"); // jump to the servlet url} catch (Exception ex) {ex. printStackTrace () ;}} public void doPost (HttpServletRequest req, HttpServletResponse res) {this. doGet (req, res );}}

(3) successful login to the welcome page to jump

// Log on to the package com. tsinghua; import javax. servlet. http. *; import java. io. *; public class Welcome extends HttpServlet {public void doGet (HttpServletRequest req, HttpServletResponse res) {// business logic try {// solves Chinese garbled res. setContentType ("text/html; charset = gbk"); PrintWriter pw = res. getWriter (); pw. println ("hello welcome! ");} Catch (Exception ex) {ex. printStackTrace () ;}} public void doPost (HttpServletRequest req, HttpServletResponse res) {this. doGet (req, res );}}

(4) Compiling the configuration file web. xml

 
   
  
   Welcome to Tomcat
    
  
        Welcome to Tomcat  
    
    
      
   
    Login
       
   
    com.lc.Login
     
     
      
   
    Login
       
   
    /login
     
    
      
   
    Logincl
       
   
    com.lc.Logincl
     
     
      
   
    Logincl
       
   
    /logincl
     
    
      
   
    Welcome
       
   
    com.lc.Welcome
     
     
      
   
    Welcome
       
   
    /welcome
     
  
  
 

(5) running result: