Cookie进行自动登录

落日映苍穹つ 2022-06-08 13:42 220阅读 0赞

main.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% 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%>"> <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">  </head> <body> <%String username=request.getParameter("username"); if(username!=null &&!username.trim().equals("")){ Cookie userCookie=new Cookie("username",username); userCookie.setMaxAge(30); response.addCookie(userCookie); }else{ Cookie[] cookies=request.getCookies(); if(cookies!=null && cookies.length>0){ for(Cookie c:cookies){ if(c.getName().equals("username")){ username= c.getValue(); } } } } if(username !=null && !username.trim().equals("")){ System.out.print(1); out.print("hello:"+username); }else{ response.sendRedirect("login.jsp"); } %> </body> </html>

测试：

如果不输入用户名的话,main.jsp里的逻辑判断会使页面重定向到登录页面：

![Center][]

输入用户名，进入main.jsp：

![Center 1][]

![Center 2][]

此时查看login.jsp页面的cookie

![Center 3][]

再次重新在login.jsp登录，但是不输入内容，查看main.jsp中从login.jsp传过来的请求头：![Center 4][]

![Center 5][]

因为该cookie被设置为有效期30秒，所以30秒后，再重新登录的话，如果不输入内容，无法进入main.jsp.

[Center]: /images/20220608/f767cf32415b4bb2a33989a4ed01ee87.png
[Center 1]: /images/20220608/ac0daf0e41684d93997e29e26c803c6f.png
[Center 2]: /images/20220608/1ac0c4d8890d4149800c9bc5565dc22b.png
[Center 3]: /images/20220608/05e19ef7ec2b43f39668a77539b73b08.png
[Center 4]: /images/20220608/17fe3b7cb15d4196984d3f50ba3b6998.png
[Center 5]: /images/20220608/2f786ab68a2a4d4fae58d67666b89b8c.png