小编给大家分享一下javaweb设计中filter粗粒度权限控制的示例分析,希望大家阅读完这篇文章之后都有所收获,下面让我们一起去探讨吧!
1 说明
我们给出三个页面:index.jsp、user.jsp、admin.jsp。
index.jsp:谁都可以访问,没有限制;
user.jsp:只有登录用户才能访问;
admin.jsp:只有管理员才能访问。
2 分析
设计User类:username、password、grade,其中grade表示用户等级,1表示普通用户,2表示管理员用户。
当用户登录成功后,把user保存到session中。
创建LoginFilter,它有两种过滤方式:
如果访问的是user.jsp,查看session中是否存在user;
如果访问的是admin.jsp,查看session中是否存在user,并且user的grade等于2。
3 代码
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.cug.web.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>UserFilter</filter-name> <filter-class>com.cug.filter.UserFilter</filter-class> </filter> <filter-mapping> <filter-name>UserFilter</filter-name> <url-pattern>/user/*</url-pattern> </filter-mapping> <filter> <filter-name>AdminFilter</filter-name> <filter-class>com.cug.filter.AdminFilter</filter-class> </filter> <filter-mapping> <filter-name>AdminFilter</filter-name> <url-pattern>/admin/*</url-pattern> </filter-mapping> </web-app>
LoginServlet.java
package com.cug.web.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.cug.domain.User; import com.cug.web.service.UserService; public class LoginServlet extends HttpServlet{ @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); resp.setContentType("text/html;charset=utf-8"); String username = req.getParameter("username"); String password = req.getParameter("password"); User user = UserService.login(username, password); if(user == null){ req.setAttribute("msg", "用户名或者密码错误"); req.getRequestDispatcher("/login.jsp").forward(req, resp); } else{ req.getSession().setAttribute("user", user); req.getRequestDispatcher("index.jsp").forward(req,resp); } } }
UserService
package com.cug.web.service; import java.util.HashMap; import java.util.Map; import com.cug.domain.User; public class UserService { private static Map<String, User> users = new HashMap<String, User>(); static{ users.put("zhu", new User("zhu", "123", 2)); users.put("xiao", new User("xiao", "123", 1)); } public static User login(String username, String password){ User user = users.get(username); if(user == null) return null; if(!user.getPassword().equals(password)) return null; return user; } }
AdminFilter
package com.cug.filter; 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 com.cug.domain.User; public class AdminFilter implements Filter{ @Override public void destroy() { } @Override public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { req.setCharacterEncoding("utf-8"); resp.setContentType("text/html;charset=utf-8"); HttpServletRequest request = (HttpServletRequest)req; User user = (User)request.getSession().getAttribute("user"); if(user == null){ resp.getWriter().print("用户还没有登陆"); request.getRequestDispatcher("/login.jsp").forward(req, resp); } if(user.getGrade() < 2){ resp.getWriter().print("您的等级不够"); return; } chain.doFilter(req, resp); } @Override public void init(FilterConfig arg0) throws ServletException { } }
UserFilter
package com.cug.filter; 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 com.cug.domain.User; public class UserFilter implements Filter{ @Override public void destroy() { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); HttpServletRequest httpReq = (HttpServletRequest)request; User user = (User)httpReq.getSession().getAttribute("user"); if(user == null){ request.getRequestDispatcher("/login.jsp").forward(request, response); } chain.doFilter(request, response); } @Override public void init(FilterConfig filterConfig) throws ServletException { } }
User
package com.cug.domain; public class User { private String username; private String password; private int grade; public User() { super(); } public User(String username, String password, int grade) { super(); this.username = username; this.password = password; this.grade = grade; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getGrade() { return grade; } public void setGrade(int grade) { this.grade = grade; } @Override public String toString() { return "User [username=" + username + ", password=" + password + ", grade=" + grade + "]"; } }
html
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <title>My JSP 'admin.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > --> </head> <body> <h2>admin.jsp</h2> <h4>${user.username }</h4> <a href="<c:url value='/index.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >首页</a><br/> <a href="<c:url value='/user/user.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >用户页</a><br/> <a href="<c:url value='/admin/admin.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >系统管理员</a><br/> </body> </html>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <title>My JSP 'user.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > --> </head> <body> <h2>user.jsp</h2> <h4>${user.username }</h4> <a href="<c:url value='/index.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >首页</a><br> <a href="<c:url value='/user/user.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >用户登陆界面</a><br> <a href="<c:url value='/admin/admin.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >管理员登陆界面</a><br> </body> </html>
用户登录
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <title>My JSP 'login.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > --> </head> <body> ${msg } <form action="<c:url value='/LoginServlet'/>" method="post"> 用户名:<input type="text" name="username"/><br/> 密码:<input type="password" name="password"/><br/> <input type="submit" value="登陆"/> </form> </body> </html>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > --> </head> <body> <h2>index.jsp</h2> <h4>${user.username }</h4> <a href="<c:url value='/index.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >首页</a><br> <a href="<c:url value='/user/user.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >用户登陆界面</a><br> <a href="<c:url value='/admin/admin.jsp'/>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >管理员登陆界面</a><br> </body> </html>
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