会话技术_概述和快速入门

会话技术_概述

概念：一次会话中包含多次请求和响应

• • 一次会话：浏览器第一次给服务器资源发送请求 会话建立 直到一方断开为止

功能：在一次会话的范围内的多次请求间 共享数据

方式：

1. 客户端会话技术：Cookie
2. 服务器端会话技术：Session

会话技术_快速入门

会话技术：Cookie

Cookie概念：客户端会话技术 将数据保存到客户端

快速入门：

• 使用步骤
  • 创建Cookie对象 绑定数据
    • new Cookie(String name,String value)
  • 发送Cookie对象
    • responese.addCookie(Cookie cookie)
  • 获取Cookie 拿到数据
    • Cookie[] request.getCookies()

java代码

CookieDemo01类

package com.bai.Cookie;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/CookieDemo01")
public class CookieDemo01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie cookie = new Cookie("msg", "hello");
        //发送Cookie
        resp.addCookie(cookie);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

CookieDemo02类

package com.bai.Cookie;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/CookieDemo02")
public class CookieDemo02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建Cookie对象
        Cookie[] cookies = req.getCookies();
       if (cookies!=null){
           for (Cookie cookie : cookies) {
               String name = cookie.getName();
               String value = cookie.getValue();
               System.out.println(name+":"+value);
           }
       }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

运行结果

Cookie_原理分析

图解

实现原理：基于响应头set-cookie和请求头cookie实现