filter实现登录拦截


LogoutServlet:

package com.kakafa.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 LogoutServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Object user_session = req.getSession().getAttribute("USER_SESSION");
        if (user_session.equals(null)){
            req.getSession().removeAttribute("USER_SESSION");
            resp.sendRedirect("/j/index.jsp");
        }else{
            resp.sendRedirect("/j/index.jsp");
        }
    }

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

LoginServlet:

package com.kakafa.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 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")){
            req.getSession().setAttribute("USER_SESSION",req.getSession().getId());
            resp.sendRedirect("/j/sys/success.jsp");
        }else{
            resp.sendRedirect("/j/error.jsp");
        }
    }

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

登陆页面index.jsp:

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

</form>
</body>
</html>

登录成功页面success.jsp：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>主页</title>
</head>
<body>
<h1>主页:登录成功！</h1>

<p><a href="/j/servlet/logout" >注销</p>


</body>
</html>

登陆失败页面error.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>错误页面</title>
</head>
<body>
<h1>登陆失败</h1>

<p><a href="/j/index.jsp" >返回到初始页面</p>
</body>
</html>

SysFilter

package com.kakafa.filter;

import javax.servlet.*;
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 {


        //假如session是空的，说明没有登录，则直接转到error页面
        //ServletRequest HttpServletRequest 是父子关系，为了获取到session强制转换一下
        HttpServletRequest request1=(HttpServletRequest) servletRequest;
        HttpServletResponse response1=(HttpServletResponse) servletResponse;

        Object user_session = request1.getSession().getAttribute("USER_SESSION");
        if (user_session==null){
            response1.sendRedirect("/j/error.jsp");
        }else{
            filterChain.doFilter(request1,response1);
        }


    }

    @Override
    public void destroy() {

    }
}

web.xml:

 <servlet>
        <servlet-name>login</servlet-name>
        <servlet-class>com.kakafa.servlet.LoginServlet</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>com.kakafa.servlet.LogoutServlet</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>com.kakafa.filter.SysFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>sysFilter</filter-name>
        <url-pattern>/sys/*</url-pattern>
    </filter-mapping>

posted @ 2021-11-23 17:22  卡卡发  阅读(108)  评论(0)    收藏  举报