Cookie&Session具体实现

Cookie与Session详解

最新推荐文章于 2024-12-06 16:11:20 发布

原创最新推荐文章于 2024-12-06 16:11:20 发布 · 246 阅读

0 ·

CC 4.0 BY-SA版权

cookie&session 专栏收录该内容

2 篇文章

订阅专栏

本文深入讲解了Cookie和Session的工作原理及应用，包括Cookie的创建、读取、删除，以及如何利用Cookie记录访问时间，同时详细介绍了Session的创建与访问过程。

Cookie

1，发送cookie

package com.oarage;

import javax.servlet.http.Cookie;
import java.io.IOException;

/**
 * 发送cookie
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class SendCookie extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
        //创建cookie对象
        Cookie cookie=new Cookie("goods","phone") ;

        //为cookie创建持久化时间---cookie信息在硬盘中保存的时间
        cookie.setMaxAge(60*10);//10分钟---时间设置为0代表删除cookie

        //设置cookie的携带路径，提高传输速度
        //如果不设置携带路径，那么该cookie信息会在访问产生该cookie的web资源所在的路径都携带cookie信息
        cookie.setPath("/cookie/NewServlet");//当访问NewServlet时才携带这个cookie
        cookie.setPath("/cookie");//当访问cookie下的所有资源都会携带这个cookie
        cookie.setPath("/");//在访问目前服务器下的资源都会携带这个cookie

        //将cookie存储的堆发送到客户端----头
        response.addCookie(cookie);
    }
}

2获得cookie

package com.oarage;

import javax.servlet.http.Cookie;
import java.io.IOException;

/**
 * 获得cookie
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class GetCookie extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
     //获取客户端携带的cookie的数据，一般情况下cookies有很多，用数组来获取
        Cookie[] cookies=request.getCookies();
        // Cookie cookie=new Cookie("goods","phone") ;
        //通过cookie的name来获得想要的cookie
        for(Cookie cookie:cookies){
            //获得cookie的名称
            String cookieName=cookie.getName();
            if(cookieName.equals("goods")){
                //获得该cookie的值
                String cookieValue=cookie.getValue();
                System.out.println(cookieValue);
            }
        }
    }
}

3删除cookie

package com.oarage;

import javax.servlet.http.Cookie;
import java.io.IOException;

/**
 * 删除cookie
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class RemoveCookie extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
      //删除客户端保存的goods-phone的cookie信息（key必须一样，vulue必须一样，就可删除key为goods的）
        Cookie cookie=new Cookie("goods","phone") ;
        //路径必须保持一致
        cookie.setPath("/cookie/NewServlet");
        //设置时间为0
        cookie.setMaxAge(0);
        response.addCookie(cookie);
    }
}

4获取上次访问的时间

package com.oarage;

import javax.servlet.http.Cookie;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 上次访问的时间
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class LastTimeCookie extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
       //获取当前时间
        Date date=new Date();
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        String currentTime=sdf.format(date);

        //第一次访问cookie
        //创建Cookie，记录当期访问时间，在cookie中不能直接放newDate（），因为在这里只能放字符串
        Cookie cookie=new Cookie("lastAccesTime",currentTime);
        //100个十分钟
        cookie.setMaxAge(60*10*100);
        response.addCookie(cookie);

        //第二次  获得客户端上次携带cookie的时间
        String lastAccesTime=null;
        Cookie[] cookies=request.getCookies();
        if(cookies!=null) {
            for (Cookie cookie1 : cookies) {
               if("lastAccesTime".equals(cookie1.getName())){
                   lastAccesTime=cookie1.getValue();
               }

            }
        }
       //在这里判断是否是第一次访问
        response.setContentType("text/html;charset=utf-8");
        if(lastAccesTime==null){
            response.getWriter().write("第一次fnagwen");
        }else{
            response.getWriter().write("上次访问时间是"+lastAccesTime);
        }
    }
}

Sesion

1创建session

package com.oarage;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * 创建cookie
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class Session extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
        //创建属于该客户端（会话）的私有的Session区域
        /**
         *  request.getSession()会内部判断该客户端是否在服务器端已经存在session
         *  如果该客户端在此服务器不存在session，那么就会创建一个新的session对象
         *  如果已经存在session，获得已经存在的session返回
         *  实质就是通过JSESSIONID判断
         */
        HttpSession session=request.getSession();

        //在此处session对象肯定不为空，所以不用判断为空（key,value）
        session.setAttribute("goods","phone");
        String id=session.getId();//该Session对象的编号Id

        //手动创建一个存储JSESSIONID的cookie，为cookie设置持久化时间
        //因位如果不手动设置的话，其中存放JSESSIONID的cookie会随着关闭客户端导致JSESSIONID也会丢失
        Cookie cookie=new Cookie("JSESSIONID",id);
        //指本项目下的所有资源
        cookie.setPath("/cookie/");
        cookie.setMaxAge(60*10);
        response.addCookie(cookie);

        response.getWriter().write("JSESSIONID是"+id);
    }
}

2访问session

package com.oarage;

import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * 创建cookie
 */
@javax.servlet.annotation.WebServlet(name = "NewServlet")
public class Session2 extends javax.servlet.http.HttpServlet {
    protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {


    }

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {

       //从session中获得存储的数据
        HttpSession session=request.getSession();
        //因为是用一个客户端的session，所以可以直接在此处获取goods
        String  attribute= (String) session.getAttribute("goods");
        response.getWriter().write(attribute+"");

    }
}