一個簡單的超市訂單管理系統（4）-使用者登出和許可權攔截

阿新 • • 發佈：2021-10-18

1.登出功能：移除session，返回登入頁面即可

　　（1）編寫移除登出功能的servlet

 1 package com.xiaoma.servlet.user;
 2 
 3 import com.xiaoma.util.Constants;
 4 
 5 import javax.servlet.ServletException;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 
 9 import java.io.IOException;
10 
11 public class LogoutServlet extends HttpServlet {
12     @Override
13     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
14         //移除session
15         req.getSession().removeAttribute(Constants.USER_SESSION);
 
16         //重定向到登入頁面
17         resp.sendRedirect(req.getContextPath()+"/login.jsp");
18     }
19 
20     @Override
21     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
22         doGet(req, resp);
23     }
24 }

　　（2）在web.xml中註冊我們的servlet，注意這裡的url-patten是走的前端的jsp/common/head.jsp下的退出走的那個url

　　（3）效果圖

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2. 登入許可權攔截

　　（1）在filter資料夾下建立一個SysFilter類檔案，用來進行登入攔截，所需的error.jsp頁面連結：https://pan.baidu.com/s/1UKtUbRBphFyIlk6RU9aR9g提取碼：5210

 1 package com.xiaoma.filter;
 2 
 3 import com.xiaoma.pojo.User;
 4 import com.xiaoma.util.Constants;
 5 
 6 import javax.servlet.*;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import java.io.IOException;
10 
11 
12 public class SysFilter implements Filter {
13 
14     @Override
15     public void init(FilterConfig filterConfig) throws ServletException {
16 
17     }
18 
19     @Override
20     public void doFilter(ServletRequest req, ServletResponse resp, FilterChain filterChain) throws IOException, ServletException {
21         //request用來獲取session，request用來重定向
22         HttpServletRequest request=(HttpServletRequest) req;
23         HttpServletResponse response=(HttpServletResponse) resp;
24 
25         //獲取session
26         User user=(User) request.getSession().getAttribute(Constants.USER_SESSION);
27 
28         //使用者session為空，就說明使用者已經登出了，或者未登入
29         if (user == null) {
30             response.sendRedirect(((HttpServletRequest) req).getContextPath()+"/error.jsp");
31         }else{
32             filterChain.doFilter(req,resp);
33         }
34     }
35 
36     @Override
37     public void destroy() {
38 
39     }
40 }

　　（2）在web.xml中註冊過濾器

1     <!--註冊許可權攔截過濾器-->
2     <filter>
3         <filter-name>SysFilter</filter-name>
4         <filter-class>com.xiaoma.filter.SysFilter</filter-class>
5     </filter>
6     <filter-mapping>
7         <filter-name>SysFilter</filter-name>
8         <url-pattern>/jsp/*</url-pattern>
9     </filter-mapping>