应用session对象模拟用户登录

红太狼 2023-10-03 21:07 64阅读 0赞

1，创建封装用户信息类，新建一个名为User的类

public class User {
        
        private String username;
        private String password;
    
        public String getUsername() {
        
            return username;
        }
    
        public void setUsername(String username) {
        
            this.username = username;
        }
    
        public String getPassword() {
        
            return password;
        }
    
        public void setPassword(String password) {
        
            this.password = password;
        }
    }
    2，创建servlet名为IndexServlet的类，用于显示网页的首页
    
    ```java
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    import java.io.IOException;
    
    @WebServlet("/IndexServlet")
    public class IndexServlet extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
         response.setContentType("text/html;charset=utf-8");
         HttpSession session=request.getSession();
         User user=(User)session.getAttribute("user");
         if (user==null){
        
             response.getWriter().print("您还没有登录，请<a href='login.html'>登录</a>");
         }
         else {
        
             response.getWriter().print("您已登录，欢迎你，"+user.getUsername()+"!");
             response.getWriter().print("<a href='LogoutServlet'>退出</a>");
         }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request,response);
        }
    }

3，编写LoginServlet，该servlet用于显示用户登录成功后的界面

import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.io.PrintWriter;
    
    @WebServlet("/LoginServlet")
    public class LoginServlet extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            response.setContentType("text/html;charset=utf-8");
            String username=request.getParameter("username");
            String password=request.getParameter("password");
            PrintWriter out=response.getWriter();
            if ("gxs".equals(username)&&("123".equals(password))){
        
                User user=new User();
                user.setUsername(username);
                user.setPassword(password);
                request.getSession().setAttribute("user",user);
                response.sendRedirect("IndexServlet");
            }
            else {
        
                out.write("用户名或密码错误，登录失败");
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request,response);
        }
    }

4，编写LogoutServlet，该servlet用于显示用户注销功能

5，在web目录下创建一个名为login的HTML文件，该文件包含用户登录表单信息

<!doctype html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport"
              content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>Document</title>
    </head>
    <body>
    <form action="LoginServlet" method="post">
        用户名:<input name="username" type="text"/><br/>
        密码:<input name="password" type="text"/><br/>
        <input type="submit" value="提交"id="bt">
    </form>
    </body>
    </html>