Cookie

Cookie: 客户端会话技术, 将数据保存在客户端, 以后每次请求都携带Cookie进行访问

Cookie的基本使用之发送

package com.itheima.web;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/aServlet")
public class AServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //发送cookie

        //1.创建cookie对象
         Cookie cookie = new Cookie("username", "zs");
         //2.发送cookie
        response.addCookie(cookie);
    }

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

Cookie的基本使用之获取

package com.itheima.web;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/bServlet")
public class BServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //从浏览器获取cookie

        //1.获取cookie数组
        Cookie[] cookies = request.getCookies();
        //遍历数组
        for (Cookie cookie : cookies) {
            //获取数据
            String name = cookie.getName();
            if ("username".equals(name)) {
                String value = cookie.getValue();
                System.out.println(name + ":" + value);
                break;
            }
        }
    }

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

Cookie细节:存活时间

        //1.创建cookie对象
         Cookie cookie = new Cookie("username", "zs");

         //cookie存活时间
        cookie.setMaxAge(7 * 24 * 60 *60);//设置为一个星期

         //2.发送cookie
        response.addCookie(cookie);

//setMaxAge()里单位是秒 负数代表存在内存里, 正数代表存在硬盘里, 0代表销毁

Cookie细节:存储中文

//发送Cookie时编码
        String value = "张三";
        //URL编码
        value = URLEncoder.encode(value, "UTF-8");

//接收Cookie时解码
String value = cookie.getValue();
value = URLDecoder.decode(value, "UTF-8");

Session

基本使用

//存数据
package com.itheima.web.session;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/demo1")
public class ASessionServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //存储到session中
        //1.获取session对象
        HttpSession session = request.getSession();
        //2.存储数据
        session.setAttribute("username", "zs");
    }

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

//取数据
package com.itheima.web.session;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/demo2")
public class BSessionServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //从session中读取数据
        //得到session
        HttpSession session = request.getSession();
        //从session1中取数据
        Object username = session.getAttribute("username");
        System.out.println(username);

    }

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

Session使用细节

  <session-config>
    <session-timeout>30</session-timeout>
  </session-config>