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Complete web login process through filter

2022-07-06 10:19:00 【Artificial intelligence cockroach】

Complete web login process through filter

frame
- Only users who get tickets can log in successfully , Tickets will be confiscated upon cancellation
Filter
- effect ：
- Guide pack
Specific code

frame

Only users who get tickets can log in successfully , Tickets will be confiscated upon cancellation

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Filter

effect ：

Deal with Chinese code
validate logon ….
Add to server and servlet Between , Used to filter requests and responses ;
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Guide pack

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Specific code

The login page index.jsp

<html>
<body>
<h2> The login page </h2>
<div style="text-align:center">
    <%--${pageContext.request.contextPath} Represents the current project web route --%>
    <%--method="post" Set request method --%>
    <form action="${pageContext.request.contextPath}/login" method="post">
        <%@ page pageEncoding="utf-8"%>
         user name ：<input type="text" name="username"> <br>
         password ：<input type="password" name="password"><br>

        <input type="submit">
    </form>
</div>

</body>
</html>

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title> error </title>
</head>
<body>
<h2> The user name does not exist or the password is wrong ！</h2>
<a href="/s1/index.jsp"> Return to login page </a>

</body>
</html>

success.jsp

success.jsp Put it in web/sys/
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<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title> A page </title>
</head>
<body>
<h1> Home page </h1>

<h2  Login successful  style="text-align:center"></h2>
<%-- Set button --%>
<a href="../logout"> Cancellation account </a>
</body>
</html>

Sign in Servlet Login

package com.tl.login;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** * @author tl *  Realize page login function ： Only by entering the correct password can you login successfully and get tickets , *  Otherwise, redirect to error.jsp page  */
public class Login extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    

        String username=req.getParameter("username");
        String password=req.getParameter("password");
        if(username.equals("admin")&&password.equals("123456")){
    
            req.getSession().setAttribute(Constant.name,req.getSession().getId());
            resp.sendRedirect("/s1/sys/success.jsp");
        }
        else {
    
            resp.sendRedirect("/s1/error.jsp");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
        doGet(req, resp);
    }
}

filter LoginFilter

package com.tl.login;


import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** * @author tl *  filter   Filter requests that don't get tickets , Respond to them on the login page  */
public class LoginFilter implements Filter {
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
        HttpServletRequest req=(HttpServletRequest) request;
        HttpServletResponse resp=(HttpServletResponse) response;

        if(req.getSession().getAttribute(Constant.name)==null){
    
            resp.sendRedirect("/s1/index.jsp");
        }
        // Current 
        chain.doFilter(request,response);
    }

    @Override
    public void destroy() {
    

    }
}

Cancellation Logout

package com.tl.login;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** * @author tl *  After the login page, you can log out   Call this class when logging out  *  Confiscate the user's ticket  */
public class Logout extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
        if(req.getSession().getAttribute(Constant.name)!=null){
    
        // Confiscate tickets 
            req.getSession().removeAttribute(Constant.name);
            resp.sendRedirect("/s1/index.jsp");
        }
        else{
    
            resp.sendRedirect("/s1/index.jsp");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
        doGet(req, resp);
    }
}

Constant class Constant

package com.tl.login;

/** * @author tl *  Define constants here  */
public class Constant {
    
    static String name="USER_NAME";

}

register web.xml

Filter through filter /s1/sys/* Web page request and response

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0" metadata-complete="true">

    <servlet>
        <servlet-name>Login</servlet-name>
        <servlet-class>com.tl.login.Login</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Login</servlet-name>
        <url-pattern>/login</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>Logout</servlet-name>
        <servlet-class>com.tl.login.Logout</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Logout</servlet-name>
        <url-pattern>/logout</url-pattern>
    </servlet-mapping>


    <filter>
        <filter-name>LoginFilter</filter-name>
        <filter-class>com.tl.login.LoginFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>LoginFilter</filter-name>
        <url-pattern>/sys/*</url-pattern>
    </filter-mapping>

</web-app>