【Tomcat】JSP使用Session、Cookie实现购物车

购物界面shop.jsp

初始页面
在这里插入图片描述
添加商品后，在session中设置属性，重定向回到shop.jsp，然后根据session的内容显示结果
Cookie设置setMaxAge可以延长session的寿命
清空购物车就是清除session

<%@ page import="javax.jms.Session" %>
<%@ page import="java.util.*" %>
<%@ page import="java.net.URLDecoder" %><%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/8/12
  Time: 10:37
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>购物</title>
    <style>
        #big{
            margin-left: 200px;
        }
        .pro img,.pro2 img{
            width: 200px;
            height: 200px;
            display: block;
            margin: 20px;
        }
        a{
            border: 2px solid black;
            border-radius: 5px;
            font-weight: bold;
            font-size: 16px;
            color: black;
        }
        a:link{
            text-decoration: none;
        }
        a:visited{
            color: black;
        }
        a:hover{
            color: green;
        }
        a:active{
            text-decoration: underline;
        }
        .pro a{
            margin-left: 20px;
            background-color: pink;
        }
        .pro2 a{
            margin-right: 20px;
            background-color: greenyellow;
        }
        .pro,.pro2{
            float: left;
            text-align: center;
        }
        .rec{
            position: relative;
            top: 20px;
            padding: 20px;
            width: 80%;
            height: 400px;
            border: solid 2px gray;
            clear: both;
        }
        span{
            font-family: "Adobe 黑体 Std R";
            font-weight: bold;
        }
        #empty{
            background-color: red;
        }
    </style>
</head>
<body>
<div id="big">
<div class="pro" name="book"><img src="img/book01.jpg">
    <span>书</span><a href="addpro?id=1">加入购物车</a></div>
<div class="pro"><img src="img/cloth01.jpg">
    <span>衣服</span><a href="addpro?id=2">加入购物车</a></div>
<div class="pro" name="mod"><img src="img/mod01.jpg">
    <span>口红</span><a href="addpro?id=3">加入购物车</a></div>
<div class="rec">
    <span>我的购物车</span>
    <a href="addpro?id=del" id="empty">清空购物车</a><br>
    <%
        String[] strs={"书","衣服","口红"};
        HttpSession session1 = request.getSession();
        Enumeration<String> names = session1.getAttributeNames();
        while (names.hasMoreElements()){
            String n=names.nextElement();
            Object attribute = session1.getAttribute(n);
            if(n.equals("1")){
                %>
    <div class="pro2" name="book"><img src="img/book01.jpg">
        <a href="addpro?id=1">数量+1</a><span><%=strs[0]+"有"+session1.getAttribute(n)+"件"%></span></div>
                <%
            }else if(n.equals("2")){
                %>
    <div class="pro2" name="book"><img src="img/cloth01.jpg">
        <a href="addpro?id=2">数量+1</a><span><%=strs[1]+"有"+session1.getAttribute(n)+"件"%></span></div>
    <%
            }else if(n.equals("3")){
    %>
    <div class="pro2" name="book"><img src="img/mod01.jpg">
        <a href="addpro?id=3">数量+1</a><span><%=strs[2]+"有"+session1.getAttribute(n)+"件"%></span></div>
    <%
            }
            System.out.println(n+"有"+attribute+"件");
        }
        System.out.println("-----------");
    %>
</div>
</div>
</body>
</html>

Servlet

package com.blb.cookie.shop;

import jdk.nashorn.internal.ir.CallNode;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Enumeration;

@WebServlet("/addpro")
public class AddProServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String proid = request.getParameter("id");
        //获取session
        HttpSession session = request.getSession();
        if ("del".equals(proid)) {
            session.invalidate();
        } else {

            String sid = session.getId();
            Cookie cookie1 = new Cookie("JSESSIONID", sid);
            cookie1.setMaxAge(60 * 60);
            response.addCookie(cookie1);
            Enumeration<String> names = session.getAttributeNames();
            Boolean hava = false;
            if (!names.hasMoreElements()) {
                session.setAttribute(proid, 1);
            }
            while (names.hasMoreElements()) {
                String n = names.nextElement();
//                System.out.println("name:" + n);
                if (n.equals(proid)) {
                    hava = true;
                    Object attribute = session.getAttribute(n);
//                    System.out.println("atrr：" + attribute);
                    int a = (Integer) attribute;
                    int b = a + 1;
//                    System.out.println("attr++:" + b);
                    session.removeAttribute(n);
                    session.setAttribute(n, b);
                }
            }
            if (!hava) {
                session.setAttribute(proid, 1);
            }
          /*  System.out.println(proid);
            System.out.println(session);
            System.out.println("addpro*******");*/
        }
        response.sendRedirect("shop.jsp");
    }
}