Filter实现权限拦截
- 用户登录之后才能进入主页！用户注销后就不能进入主页了！
1.用户登录之后，向Sesison中放入用户的数据
2.进入主页的时候要判断用户是否已经登录;要求:在过滤器中实现!
包结构
代码演示
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="/servlet/login" method="post">
<input type="text" name="username" id=""> <br>
<input type="submit" value="登录">
</form>
</body>
</html>
LoingServlet
//为了简洁，导入的包省去了
public class LoginServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String username = req.getParameter("username");
if("admin".equals(username)){
//登录成功 进入成功页面并且把相关信息保存到session
req.getSession().setAttribute("USER_SESSION",req.getSession().getId());
resp.sendRedirect("/sys/success.jsp");
}else{
//登录失败
resp.sendRedirect("/error.jsp");
}
}
}
success.jsp和error.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%--<%--%>
<%-- //为了不让用户直接注销后地址栏输入成功页面的地址进入 第一种解决 第二种解决过滤器--%>
<%-- 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>
<%--error.jsp页面--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登录失败</h1>
<a href="/login.jsp">返回登录页面</a>
</body>
</html>
LogoutServlet
package com.tian.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 doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Object user_session = req.getSession().getAttribute("USER_SESSION");
if(user_session!=null){
req.getSession().removeAttribute("USER_SESSION");
resp.sendRedirect("/login.jsp");
}else{
resp.sendRedirect("/login.jsp");
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
}
为了不让用户直接注销后地址栏输入成功页面的地址进入,添加过滤器SysFilter
SysFilter
package com.tian.servlet;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SysFilter implements Filter {
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain filterChain) throws IOException, ServletException {
// ServletRequest HttpServletRequest
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
Object user_session = request.getSession().getAttribute("USER_SESSION");
if(user_session==null){
response.sendRedirect("/error.jsp");
}
filterChain.doFilter(request,response);
}
}
web.xml配置
<?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>LoginServlet</servlet-name>
<servlet-class>com.tian.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/servlet/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>com.tian.servlet.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/servlet/logout</url-pattern>
</servlet-mapping>
<filter>
<filter-name>SysFilter</filter-name>
<filter-class>com.tian.servlet.SysFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>SysFilter</filter-name>
<url-pattern>/sys/*</url-pattern>
</filter-mapping>
</web-app>