重定向循环【过滤器Filter】
重定向循环【过滤器Filter】
1,问题如下:
2、打印一下请求的资源,发现:
3、分析原因:
问题出现在过滤器上,【web.xml 文件的配置上,我们配置是过滤所有资源: /*】,过滤器是把所有请求都过滤,第一次在浏览器输入 /login.jsp的请求,也被过滤器过滤了,导致它的用户没有存储到session中。
4、解决:过滤器过滤之前需要进行判断,当判断为login.jsp 或者 loginServlet 的请求资源时,就不进行过滤,放行。
// System.out.println("当前正在过滤的资源:" + req.getRequestURI()); //排除 掉过滤login.jsp 和 loginServlet的 情况 String requestUri = req.getRequestURI(); if(!("/login.jsp".equals(requestUri) || "/login".equals(requestUri))) { //过滤没有登录的情况 Object user = req.getSession().getAttribute("USER_IN_SESSION"); if(user == null) { //没有登录 resp.sendRedirect("/login.jsp"); return; } }
❀ 最后,本例子的全部代码,包括配置文件如下:
❀ 登录过滤器 CheckLoginFilter
package com.shan.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 检查登录的过滤器 * @author Huangyujun * */ public class CheckLoginFilter implements Filter{ @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { //类型转换 HttpServletRequest req = (HttpServletRequest)request; HttpServletResponse resp = (HttpServletResponse)response; // System.out.println("当前正在过滤的资源:" + req.getRequestURI()); //排除 掉过滤login.jsp 和 loginServlet的 情况 String requestUri = req.getRequestURI(); if(!("/login.jsp".equals(requestUri) || "/login".equals(requestUri))) { //过滤没有登录的情况 Object user = req.getSession().getAttribute("USER_IN_SESSION"); if(user == null) { //没有登录 resp.sendRedirect("/login.jsp"); return; } } //放行 chain.doFilter(req, resp); } }
❀ 处理登录请求 LoginServlet
package com.shan.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 登录的servlet * @author Huangyujun * */ @WebServlet("/login") public class LoginServlet extends HttpServlet{ @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //接收 处理 跳转 String name = req.getParameter("username"); String password = req.getParameter("password"); System.out.println(name +"_" + password); //登录完就把用户的账号设置到session中去 req.getSession().setAttribute("USER_IN_SESSION", name); resp.sendRedirect("/welcome.jsp"); } }
❀ 登录界面的jsp login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"%> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <form action="/login" method="post"> 账号:<input type="text" name="username" required/><br/> 密码:<input type="password" name="password"/><br/> <input type="submit" value="提交"/> </form> </body> </html>
❀ 欢迎、function1、function2、function3界面的jsp welcom.jsp、function1.jsp、function2.jsp、function3.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"%> <hr/> <a href="/function1.jsp">功能1</a> <a href="/function2.jsp">功能2</a> <a href="/function3.jsp">功能3</a>
<%@ page language="java" contentType="text/html; charset=UTF-8"%> <hr/> 功能1
<%@ page language="java" contentType="text/html; charset=UTF-8"%> <hr/> 功能3
<%@ page language="java" contentType="text/html; charset=UTF-8"%> <hr/> 功能2
❀web.xml 配置文件
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0"> <display-name>filter-listener</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>CheckLoginFilter</filter-name> <filter-class>com.shan.filter.CheckLoginFilter</filter-class> </filter> <filter-mapping> <filter-name>CheckLoginFilter</filter-name> <!-- 对哪些资源做出过滤 --> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
✿ 优化一下:
<filter> <filter-name>CheckLoginFilter</filter-name> <filter-class>com.shan.filter.CheckLoginFilter</filter-class> <!-- 通过初始化参数,在初始化参数存放不用过滤的请求资源--> <!-- 但是当uncheckuris.xml的不用过滤的请求资源过多,也不完美的解决 --> <!-- 通过规定不需要过滤的资源全部放到 /system 下【合理设计,优化】 --> <!-- <init-param> <param-name>unCheckUris</param-name> <param-value>uncheckuris.xml</param-value> </init-param> --> <init-param> <param-name>unCheckUris</param-name> <param-value>/system/*</param-value> </init-param> </filter> <filter-mapping> <filter-name>CheckLoginFilter</filter-name> <!-- 对哪些资源做出过滤 --> <url-pattern>/*</url-pattern> </filter-mapping>
本文来自博客园,作者:一乐乐,转载请注明原文链接:https://www.cnblogs.com/shan333/p/15656663.html