<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> ?<head> ?<meta http-equiv="content-type" content="text/html; charset=UTF-8"> ?</head> ?<body> ???<form action="/day19/welcome.jsp" method="post"> ???????<table border="1" align="center"> ???????????<caption><br>用户登录</caption> ???????????<tr> ???????????????<th>用户名</th> ???????????????<td><input type="text" name="username"/></td> ???????????</tr> ???????????<tr> ???????????????<th>密码</th> ???????????????<td><input type="password" name="password"/></td> ???????????</tr> ???????????<tr> ???????????????<th>角色</th> ???????????????<td> ???????????????????<select name="role"> ???????????????????????<option value="普通用户">普通用户</option> ???????????????????????<option value="管理员">管理员</option> ???????????????????</select> ???????????????</td> ???????????</tr> ???????????<tr> ???????????????<td colspan="2" align="center"> ???????????????????<input type="submit" value="提交"/> ???????????????</td> ???????????</tr> ???????</table> ???</form> ?</body></html>fiter处理
import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//对敏感目录进行认证[课堂练习1]public class FilterDemo7 implements Filter { ???public void init(FilterConfig filterConfig) throws ServletException { ???} ???public void doFilter(ServletRequest req, ServletResponse res,FilterChain chain) throws IOException, ServletException { ???????HttpServletRequest request = (HttpServletRequest) req; ???????HttpServletResponse response = (HttpServletResponse) res; ???????//设置请求体编码方式 ???????request.setCharacterEncoding("UTF-8"); ???????//取得用户请求参数 ???????String username = request.getParameter("username"); ???????String password = request.getParameter("password"); ???????String role = request.getParameter("role"); ???????//判段 ???????if(username!=null && password!=null && role!=null && username.trim().length()>0 && password.trim().length()>0 && role.trim().length()>0){ ???????????if("普通用户".equals(role)){ ???????????????request.setAttribute("message","欢迎普通用户<font color=‘blue‘>"+username+"</font>登录"); ???????????????request.setAttribute("flag","user"); ???????????}else if("管理员".equals(role)){ ???????????????request.setAttribute("message","欢迎管理员<font color=‘red‘>"+username+"</font>登录"); ????????????????request.setAttribute("flag","admin"); ???????????} ???????????chain.doFilter(request,response); ???????} ???} ???public void destroy() { ???}}结果显示
<%@ page language="java" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> ?<body> ???${message}<br/> ???<c:choose> ???????<c:when test="${requestScope.flag==‘admin‘}"> ???????????<a href="#">下载</a> ???????</c:when> ???????<c:otherwise> ???????????下载 ???????</c:otherwise> ???</c:choose> ?</body></html>web.xml
<filter> ???<filter-name>FilterDemo7</filter-name> ???<filter-class>cn.itcast.web.filter.FilterDemo7</filter-class> ?</filter> ?<filter-mapping> ???<filter-name>FilterDemo7</filter-name> ???<url-pattern>/welcome.jsp</url-pattern> ?</filter-mapping>Filter--对目录实现URL级别的角色认证---学习笔记
原文地址：http://blog.51cto.com/357712148/2105129