在web项目中写一个过滤器实现用户不登陆，直接给链接，无法进入页面，而重定向到登陆界面的功能。

项目是用springMVC+spring+hibernate实现 （和这个没有多大关系）

第一步：

首先写一个登录权限过滤类--LoginFilter类实现Filter接口

1 package com.agen.util; 2  3 import java.io.IOException; 4  5 import javax.servlet.Filter; 6 import javax.servlet.FilterChain; 7 import javax.servlet.FilterConfig; 8 import javax.servlet.ServletException; 9 import javax.servlet.ServletRequest;10 import javax.servlet.ServletResponse;11 import javax.servlet.http.HttpServletRequest;12 import javax.servlet.http.HttpServletResponse;13 import javax.servlet.http.HttpSession;14 15 import org.springframework.util.Assert;16 import org.springframework.util.StringUtils;17 18 import com.agen.entity.User;19 20 /**21  * 首先写一个登录权限过滤类--LoginFilter类实现Filter接口22  * @author 申旭栋23  *下面这三个方法是必须要实现的24  */25 public class LoginFilter implements Filter {26 27     @Override28     public void init(FilterConfig filterConfig) throws ServletException {29         // TODO Auto-generated method stub30     }31 32     33     @Override34     public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {35         // 获得在下面代码中要用的request,response,session对象36         HttpServletRequest servletRequest = (HttpServletRequest) request;37         HttpServletResponse servletResponse = (HttpServletResponse) response;38         HttpSession session = servletRequest.getSession();39 40         // 获得用户请求的URI41         String path = servletRequest.getRequestURI();42         43         // 从session里取用户44         User user = (User) session.getAttribute("user");45 46         // 登陆页面无需过滤47         if("/biologyInfo/".equals(path) || "/biologyInfo/login/login1.htmls".equals(path)) {48             chain.doFilter(servletRequest, servletResponse);49             return;50         }51 52         // 判断如果没有取到用户信息,说明这个请求是没有登录就在请求     就跳转到登陆页面 53         if (user == null) {54             // 跳转到登陆页面55             servletResponse.sendRedirect("/biologyInfo/login/login1.htmls");56         } else {57             // 已经登陆,继续此次请求58             chain.doFilter(request, response);59         }60 61     }62 63     @Override64     public void destroy() {65         // TODO Auto-generated method stub66     }67 68 }

第二步：

在web.xml中配置一下filter

1 
       2     
      
        3         
       
        login
        4         
       
        com.agen.util.LoginFilter
        5     
       6  7     
      
        8         
       
        login
        9         
       
        *.htmls
       
       10     
      

这样这个过滤器就写成了。

说明：

1.在web.xml中配置的filter的 <url-pattern>参数中的值，意思就是拦截的请求路径，就是浏览器的地址栏中的URL，因为页面上不论是页面，还是js文件，还是css文件都是通过请求得到的。

 

 

2.而上面的web.xml中配置的 <url-pattern>*.htmls</url-pattern>表示拦截仅拦截.htmls结尾的URL，而将js或者css文件结尾的URL都放过。

3.而访问页面都是通过以下这样的请求去访问的页面，

http://192.168.16.104:8080/biologyInfo/login/geneinfo.htmls

http://192.168.16.104:8080/biologyInfo/login/welcome1.htmls

而这些都是先去找了后台的controller，从服务器才去的页面

贴出服务器端的代码：

1 package com.agen.controller;  2   3 import java.util.UUID;  4   5 import javax.annotation.Resource;  6 import javax.servlet.http.HttpServletRequest;  7 import javax.servlet.http.HttpSession;  8   9 import org.hibernate.Criteria; 10 import org.hibernate.Session; 11 import org.hibernate.SessionFactory; 12 import org.hibernate.criterion.Criterion; 13 import org.hibernate.criterion.Restrictions; 14 import org.springframework.beans.factory.annotation.Autowired; 15 import org.springframework.http.HttpRequest; 16 import org.springframework.stereotype.Controller; 17 import org.springframework.ui.Model; 18 import org.springframework.util.Assert; 19 import org.springframework.web.bind.annotation.RequestMapping; 20 import org.springframework.web.bind.annotation.ResponseBody; 21  22 import com.agen.entity.User; 23 import com.agen.service.AuthorityService; 24 import com.agen.service.RoleService; 25 import com.agen.service.UserSevice; 26 import com.fasterxml.jackson.annotation.JsonCreator.Mode; 27  28  29 @Controller() 30 @RequestMapping("login") 31 public class LoginController { 32      33     @Resource(name="userSevice") 34     private UserSevice userService; 35      36     @Resource(name="roleService") 37     private RoleService roleService; 38      39     @Resource(name="authorityService") 40     private AuthorityService authorityService; 41      42     @Autowired 43     private SessionFactory sessionFactory; 44      45     public Session getCurrentSession() { 46         // 需要开启事物，才能得到CurrentSession  getCurrentSession()是获取已有的 没有  就创建新的 47         return sessionFactory.getCurrentSession(); 48     } 49      50      51     @RequestMapping("/login1") 52     public String login(User user, Model model,HttpServletRequest request){ 53         if(user.getUserName()==null &&user.getPassword()==null){ 54             model.addAttribute("error", "0"); 55             return "../../../index"; 56         }else{ 57             Criteria criteria = getCurrentSession().createCriteria(User.class); 58             criteria.add(Restrictions.eq("userName", user.getUserName())); 59             User user2 = userService.uniqueResult(criteria); 60             if(user2 == null) { 61                 model.addAttribute("error", "1"); 62                 return "../../../index"; 63             } else if(!( user2.getPassword() .equals(user.getPassword()) )){ 64                 model.addAttribute("error", "2"); 65                 return "../../../index"; 66             } 67             Assert.notNull(user); 68             HttpSession session = request.getSession(); 69             session.setAttribute("user", user); 70             return "/index/index"; 71         } 72          73     } 74      75     @RequestMapping("/register") 76     @ResponseBody 77     public boolean register(User user){ 78         boolean flag = false; 79         user.setUserId(UUID.randomUUID().toString()); 80         Criteria criteria = getCurrentSession().createCriteria(User.class); 81         criteria.add(Restrictions.eq("userName", user.getUserName())); 82         User user2 = userService.uniqueResult(criteria); 83         if(user2 != null){ 84             flag = false; 85         }else{ 86             userService.save(user); 87             flag = true; 88         } 89         return flag; 90     } 91      92      93     /** 94      * 页面二级菜单 95      * @return 96      */ 97     @RequestMapping("/welcome1") 98         public String welcome(){ 99         100         return "/index/welcome";101     }102     @RequestMapping("/geneinfo")103     public String geneinfo(){        104     return "/geneinfo/geneinfoone";105     }106     107 }