cookie - 提示上一次访问该网页的时间

 1 package cn.itcast.web.servlet;
 2 
 3 import javax.servlet.ServletException;
 4 import javax.servlet.annotation.WebServlet;
 5 import javax.servlet.http.Cookie;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import java.io.IOException;
10 import java.net.URLDecoder;
11 import java.net.URLEncoder;
12 import java.text.SimpleDateFormat;
13 import java.util.Date;
14 
15 @WebServlet("/cookieServlet")
16 public class CookieServlet extends HttpServlet {
17     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
18         // 获取PrintWriter流之前设置响应的消息体的数据格式以及编码
19         response.setHeader("content-type", "text/html;charset=utf-8");
20 
21         // 1.获取所有Cookie
22         Cookie[] cookies = request.getCookies();
23         boolean flag = false;   // 没有叫做lastTime名称的cookie
24 
25         // 2.遍历cookie数组
26         if (cookies != null) {
27             for (Cookie cookie : cookies) {
28                 if (cookie.getName().equals("lastTime")) {  // 不是第一次访问
29                     flag = true;
30 
31                     String value = cookie.getValue();
32                     value = URLDecoder.decode(value, "utf-8");  // URL解码
33                     response.getWriter().write("欢迎回来，您上次的访问时间是" + value);
34 
35                     // 将cookie的value值改为此次登录的时间，重新发送cookie
36                     Date date = new Date();
37                     SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
38                     String str_date = sdf.format(date);
39                     str_date = URLEncoder.encode(str_date, "utf-8");    // URL编码，因为str_date中包含空格，如果不进行URL编码将会报错
40                     cookie.setValue(str_date);
41                     cookie.setMaxAge(30 * 24 *60 *60);　// 设置cookie的存活时间
42                     response.addCookie(cookie);
43                     break;
44                 }
45             }
46         }
47 
48         if (cookies == null || flag == false){  // 第一次访问
49             response.getWriter().write("<h1>您好，欢迎您首次访问<h1>");
50 
51             Date date = new Date();
52             SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
53             String str_date = sdf.format(date);
54             str_date = URLEncoder.encode(str_date, "utf-8");
55             Cookie cookie = new Cookie("lastTime", str_date);
56             cookie.setMaxAge(30 * 24 *60 *60);
57             response.addCookie(cookie);
58         }
59 
60 
61     }
62 
63     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
64         this.doPost(request, response);
65     }
66 }