[javaweb]javaweb中的cookie和session区别与各自实现

cookie，session

会话：用户打开一个浏览器，点击了很多按钮，访问多个web资源，关闭浏览器，这个过程可以称为会话。

客户端 服务端

• 1.服务端给客户端一个信件，客户端下次访问服务器的时候带上信件就可以了；cookie
• 2.服务器登记你来过，下次来的时候我来匹配你；session

保存客户端信息的两种方式：

• cookie
  • 客户端技术：请求和响应
• session
  • 服务器端技术，保存客户端信息，把信息或者数据放在session中

package com.javaweb.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

/**
 * @author panglili
 * @create 2022-07-19-19:39
 */
public class Cookie extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");

        PrintWriter writer = resp.getWriter();

        javax.servlet.http.Cookie[] cookies = req.getCookies();

        if(cookies!=null){
            writer.write("time:");
            for(int i=0;i<cookies.length;i++){
                javax.servlet.http.Cookie cookie=cookies[i];
                if(cookie.getName().equals("lastLoginTime")){
                    long lastLoginTime=Long.parseLong(cookie.getValue());
                    Date date = new Date(lastLoginTime);
                    System.out.println("*******");
                    writer.write(date.getDate());
                    writer.write(date.toLocaleString());
                }
                System.out.println("$$$$$$$$");
            }

        }else{
            writer.write("first inter");
        }

           javax.servlet.http.Cookie cookie1;
        cookie1 = new javax.servlet.http.Cookie("lastLoginTime", System.currentTimeMillis()+"");

        //cookie1.setMaxAge(24*60*60);
        resp.addCookie(cookie1);
    }


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


}

session实现：

• 服务器给每个用户创建一个session对象。
• 一个session独占一个浏览器，只要浏览器没关，session就可以存在

package com.javaweb.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * @author panglili
 * @create 2022-07-19-20:32
 */
public class Session extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //解决乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        //得到session
        HttpSession session = req.getSession();

        //给session存值,可以通过其他session获取
        session.setAttribute("name","heihe");

        //获取session的id
        String id = session.getId();

        //判断是不是第一次创建
        if(session.isNew()){
            resp.getWriter().write("session创建成功"+id);
        }else{
            resp.getWriter().write("session已经存在"+id);
        }

    }



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



}

<servlet>
    <servlet-name>session</servlet-name>
    <servlet-class>com.javaweb.servlet.Session</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>session</servlet-name>
    <url-pattern>/session</url-pattern>
</servlet-mapping>
<!--session失效时间-->
<session-config>
    <session-timeout>15</session-timeout>
</session-config>