JavaWeb_实现用户页面跳转

最新推荐文章于 2025-05-22 10:38:33 发布

Y1_King

最新推荐文章于 2025-05-22 10:38:33 发布

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文章标签： java intellij-idea

本文链接：https://blog.youkuaiyun.com/king_xbstudy/article/details/124251301

本文展示了如何使用JavaWeb实现用户登录页面、登录处理Servlet、成功及失败页面，并通过过滤器进行权限检查。当用户输入正确用户名（如'admin'）时，系统重定向至成功页面，否则跳转到错误页面。同时，还实现了注销功能，注销后用户将被引导回登录界面。

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JavaWeb_实现用户页面跳转

1.登录界面(Login.jsp)

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>登录</h1>
<form action="/servlet/login" method="post">
    <input type="text" name="username">
    <input type="submit">
</form>
</body>
</html>

2.登录请求(LoginServlet)

package com.king.servlet;

import com.king.util.Constant;

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

    public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取前端请求的参数
        String username = req.getParameter("username");
        if (username.equals("admin")){
            //登录成功
            req.getSession().setAttribute(Constant.USER_SESSION,req.getSession().getId());
            resp.sendRedirect("/sys/success.jsp");
        }else {
            //登录失败
            resp.sendRedirect("/error.jsp");
        }
    }

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

3.成功页面（success.jsp）

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%--<%--%>
<%--    Object userSession = request.getSession().getAttribute("USER_SESSION");--%>
<%--    if (userSession==null){--%>
<%--        response.sendRedirect("/Login.jsp");--%>
<%--    }--%>
<%--%>--%>
<h1>主页</h1>
<p><a href="/servlet/logout">注销</a></p>
</body>
</html>

4.失败页面（error.jsp）

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>错误</h1>
<h3>没有权限，用户名错误</h3>
<a href="/Login.jsp">返回登录页面</a>
</body>
</html>

5.过滤器（SysFilter）

package com.king.filter;

import com.king.util.Constant;

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

public class SysFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        if (request.getSession().getAttribute(Constant.USER_SESSION)==null){
            response.sendRedirect("/error.jsp");
        }

        chain.doFilter(request,response);
    }

    public void destroy() {

    }
}

6.权限请求（LogoutServlet）

package com.king.servlet;

import com.king.util.Constant;

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

public class LogoutServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Object user_session = req.getSession().getAttribute(Constant.USER_SESSION);
        if (user_session!=null){
            req.getSession().removeAttribute(Constant.USER_SESSION);
            resp.sendRedirect("/Login.jsp");
        }
    }

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

7.重置常量——USER_SESSION

package com.king.util;

public class Constant {
    public final static String USER_SESSION = "USER_SESSION";
}

8.配置servlet和filter

 <servlet>
            <servlet-name>LoginServlet</servlet-name>
            <servlet-class>com.king.servlet.LoginServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>LoginServlet</servlet-name>
            <url-pattern>/servlet/login</url-pattern>
        </servlet-mapping>

        <servlet>
            <servlet-name>Logoutervlet</servlet-name>
            <servlet-class>com.king.servlet.LogoutServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Logoutervlet</servlet-name>
            <url-pattern>/servlet/logout</url-pattern>
        </servlet-mapping>

        <filter>
            <filter-name>SysFilter</filter-name>
            <filter-class>com.king.filter.SysFilter</filter-class>
        </filter>
        <filter-mapping>
            <filter-name>SysFilter</filter-name>
            <url-pattern>/sys/*</url-pattern>
        </filter-mapping>