Cookie学习总结-显示上一次访问时间

最新推荐文章于 2025-12-02 15:55:42 发布

转载最新推荐文章于 2025-12-02 15:55:42 发布 · 152 阅读

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CC 4.0 BY-SA版权

原文链接：https://my.oschina.net/u/2411130/blog/477352

文章标签：

#java

本文介绍了一个简单的Servlet示例，通过使用Java Servlet中的Cookie来记录用户的最后访问时间，并在每次访问时更新这个时间。通过CookieDemoServlet和index.jsp页面展示如何读取和设置Cookie。

CookieDemoServlet.java

package blank.servlet;

import java.io.IOException;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CookieDemoServlet extends HttpServlet {


    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //定义cookie对象
        Cookie cookie = null;
        //请求request中
        Cookie cookies[] = request.getCookies();
        //遍历cookies信息
        if(cookies!=null){
            for(Cookie ck:cookies){
                 //获取每个cookie中的信息
                System.out.println(ck.getName()); //cookie的名称
                System.out.println(ck.getValue()); //对应的value值
                System.out.println(ck.getPath()); //有效目录
                System.out.println(ck.getMaxAge());//在浏览器上 cookie有效时间
                System.out.println(ck.getDomain());//有效的域

                String name = ck.getName();
                //判断cookie是否存在
                if("lasttimes".equals(name)){
                    cookie=ck;
                }
            }
        }

        //添加一个cookie
        if(cookie==null){
            //创建一个cookie对象 name value值
            cookie=new Cookie("lasttimes", System.currentTimeMillis()+"");
            System.out.println("====create==cookie=====");
        }
        request.setAttribute("lasttimes", new Date(Long.valueOf(cookie.getValue())));
        //重新改变值
        cookie.setValue(System.currentTimeMillis()+"");
        //添加到响应中
        response.addCookie(cookie);

        request.getRequestDispatcher("/index.jsp").forward(request, response);
    }





    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doGet(request, response);
    }

}

index.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">
<!-- <link rel="stylesheet" type="text/css" href="styles.css"> -->

</head>

<body>
    <div>上次访问的时间：${lasttimes}</div>
    <div>
        <a href="./ck.do">第一次访问</a>
    </div>
</body>
</html>

转载于:https://my.oschina.net/u/2411130/blog/477352