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渚漪Day21——JavaWeb 11【Filter实现权限拦截】 Filter实现权限拦截

分类: IT文章 • 2023-11-26 22:40:13

页面

  • 登录页面 login.jsp
  • 登录成功页面 /sys/success.jsp
  • 登录失败页面 error.jsp

功能

输入用户名正确则登录成功进入 /sys/success.jsp

否则进入 error.jsp

利用session判断是否处于登录状态，有登录权限

若不处于则即便输入/sys/success.jsp 过滤器拦截跳转error.jsp

代码

JSP

login.jsp

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

</body>
</html>

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>主页</title>
</head>
<body>
    <h1>成功进入主页</h1>

    <p><a href="/servlet/logout">注销</a></p>
</body>
</html>

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>error</title>
</head>
<body>
    <h1>登录失败</h1>
    <p><a href="/servlet/logout">返回首页</a></p>
</body>
</html>

Servlet

login.java

package servlet;

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 login extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String username = req.getParameter("username");
        System.out.println(username);
        req.getSession().setAttribute("user_session",req.getSession().getId());
        if(username.equals("admin")){
            resp.sendRedirect("/sys/success.jsp");
        }
        else{
            resp.sendRedirect("/error.jsp");
        }

    }

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

logout.java

package servlet;

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 logout extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Object user_session = req.getSession().getAttribute("user_session");

        if(user_session!=null){
           // System.out.println(user_session);
            req.getSession().removeAttribute("user_session");
        }
        resp.sendRedirect("/login.jsp");
    }

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

Filter

sysFiter.java

package Filter;

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 {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) servletRequest;
        HttpServletResponse resp = (HttpServletResponse) servletResponse;

        if(req.getSession().getAttribute("user_session")==null)
        {
            resp.sendRedirect("/error.jsp");
        }


        filterChain.doFilter(servletRequest, servletResponse);

    }

    @Override
    public void destroy() {

    }
}

XML

<?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">
    <servlet>
        <servlet-name>login</servlet-name>
        <servlet-class>servlet.login</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>login</servlet-name>
        <url-pattern>/servlet/login</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>logout</servlet-name>
        <servlet-class>servlet.logout</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>logout</servlet-name>
        <url-pattern>/servlet/logout</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>SysFilter</filter-name>
        <filter-class>Filter.SysFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>SysFilter</filter-name>
        <url-pattern>/sys/*</url-pattern>
    </filter-mapping>
</web-app>

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