javaweb实现购物车功能

本文介绍: Jav aWeb 实现购物车功能(javaweb练手小项目)欢迎阅读

本篇 文章讲的是如何 使用 javaweb相关知识 模拟 购物车 功能

(web练手小项目)

使用到的相关知识(部分知识点在文章中简单涉及到):

html cs javascript jsp servlet ajax jQue ry Mysql MyBa tis(持久层框架，用来连接数据库，这里可以使用 jdbc进行数据库的连接) 功能使用MVC设计模式，以及三层架构思想

注: 本篇使用Ses s ion对购物车进行存储,具体参考下文Wel comeServ let.java

功能实现效果:

购物车为空状态

功能大致目录结构:

前端界面代码:

(1) sh op car.jsp(购物车界面)

&lt;%@ page import="edu.pdsu.shop.pojo.CarGoods" %&gt;
&lt;%@ page import="java.util.List" %&gt;
&lt;%@ page contentType="text/html;charset=UTF-8" language="java" %&gt;
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>shop car</title>
    <link rel="stylesheet" href="css/shoplist.css" type="text/css">
    <script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-3.6.1.min.js"></script>
</head>
<style type="text/css">
    th, td {
        border-bottom: 1px solid green;
    }
    th {
        background-color: #4CAF50;
        color: white;
    }
    table{
        text-align: center;
    }
</style>
<body style="background-color: #ffffe0" background="img/11.webp">
<h1 style="color: white;margin-left: 600px;margin-top: 50px">购物车</h1>
<table border="1px" cellspacing="0" style="border-color: #d7ffff ; margin-top: 5px ; margin-left: 340px">
    <script type="text/javascript">
        function judgeDelete(carGoodsName) {
            if (confirm("是否删除" + carGoodsName)) {
                window.location.href = "${pageContext.request.contextPath}/deleteCarGoods?carGoodsName=" + carGoodsName
            } else {
                alert("取消删除成功")
            }
        }
    </script>

    <c:if test="${empty carGoodsList}">
        <%--<h1 style="margin-left: 580px;margin-top: 170px">购物车为空</h1>--%>
        <div style="margin-left: 500px;margin-top: 56px">
            <img src="img/carnull.jpg" width="300px" height="200px">
        </div>
    </c:if>

    <c:if test="${not empty carGoodsList}">
        <tr>
            <th>商品名称</th>
            <th>商品描述</th>
            <th>价格</th>
            <th>购买数量</th>
            <th>操作</th>
        </tr>
    </c:if>
    <c:if test="${not empty carGoodsList}">

        <c:forEach items="${carGoodsList}" var="CarGoods">
            <tr>
                <td>${CarGoods.carGoodsName}</td>
                <td>${CarGoods.carGoodsDes}</td>
                <td>${CarGoods.carGoodsPrice}</td>
                <td>${CarGoods.buyCount}</td>
                <td>
                    <input id="deleteCarGoods" type="button" style="text-decoration: none"
                           onclick="judgeDelete('${CarGoods.carGoodsName}')" value="删除"/>
                </td>
            </tr>

        </c:forEach>
    </c:if>
</table>

<c:if test="${not empty carGoodsList}">
    <h3 style="margin-left: 340px;color: white">目前您购物车的总价格为:${money}元人民币</h3>
</c:if>

<br>
<br>
<br>
<input class="backshowlist" type="button" value="返回商品显示页"
       onclick="window.location.href='${pageContext.request.contextPath}/showlist'">
</body>
</html>

(2) sh op list.jsp(商品页)

<%@ page contentType="text/html;charset=utf-8" language="java" isELIgnored="false" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<head>
    <title>myshop</title>
    <link rel="stylesheet" href="css/shoplist.css" type="text/css">
    <script type="text/javascript" src="js/jquery-3.6.1.min.js"></script>
</head>
<style type="text/css">
    th, td {
        border-bottom: 1px solid green;
    }
    th {
        background-color: #4CAF50;
        color: white;
    }
    table{
        text-align: center;
    }
</style>

<body style="background-color: #ffffe0" background="img/11.webp">
<h2 style="color: skyblue">:)</h2>

<script type="text/javascript">
    $(function () {
        $("#showbtn").click(function () {
            $.ajax({
                type: "GET",
                url: "${pageContext.request.contextPath}/judgecar",
                async: true,
                success: function (j) {
                    if (j == "购物车为空") {
                        alert("购物车为空")
                    } else {
                        window.location.href = "${pageContext.request.contextPath}/shopcar.jsp"
                    }
                }
            })
        })
    })
</script>
<h1 style="color: white;margin-left: 600px">商品页</h1>
<button id="showbtn" class="showcarbtn">查看购物车</button>
<form action="${pageContext.request.contextPath}/beforeCar" method="post" id="form_">
    <table  cellspacing="0" style="  margin-top: 5px ; margin-left: 270px ;border-color: #8bff73">
        <tr>
            <th>序号</th>
            <th>商品名称</th>
            <th>商品描述</th>
            <th>商品价格(元)</th>
            <th>库存数量</th>
            <th>添至购物车</th>
        </tr>

        <c:forEach items="${goodss}" var="goods" varStatus="goodStatus">
            <tr>
                <td>${goodStatus.count}</td>
                <td>${goods.goodsName}</td>
                <td>${goods.goodsDes}</td>
                <td>${goods.goodsPrice}</td>
                <td>${goods.goodsCount}</td>
                <td>
                    <input type="checkbox" name="buy" value="${goods.goodsName}" style="margin-left: 30px">
                </td>
            </tr>
        </c:forEach>
    </table>
    <br>

    <input type="button" value="确定" id="btn" class="ensure">
    &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
    <input type="reset" value="重置" class="reset">

</form>

<script type="text/javascript">
    $(function () {
        $("#btn").click(function () {
            var flag = false;
            var $checkbox = $(":checkbox");
            /*for (var i = 0; i < $checkbox.length; i++) {
                if($checkbox[i].checked){
                    flag = true;
                }
            }*/
            //使用jQuery循环jQuery对象，其实jQuery对象就是一个dom数组
            /*$checkbox.each(function (i , n) {
                if(n.checked){
                    flag = true
                }
            })*/
            $.each($checkbox,function (i,n) {
                if(n.checked){
                    flag = true;
                }
            })
            if (flag == false) {
                alert("未选择商品")
            } else {
                var $formElement = $("#form_")[0];
                $formElement.submit();
            }
        })
    })
</script>
</body>
</html>

后端servlet 代码:

欢迎页(WelcomeServlet.java)

欢迎页介绍：当把购物车初始化在ShopServlet.java或者其他servlet中刷新浏览器页面 session中的购物车状态会出现异常,因此我的想法是在欢迎页中创建购物车对象并存储到Session中

写此欢迎页代码前需要在web.xml 配置文件中配置一下代码

配置后会默认以/welcome为项目默认路径进行访问(需要注意<welcome-file>这里不需要 /</welcome-file>)

<!--配置欢迎页-->
    <welcome-file-list>
        <welcome-file>welcome</welcome-file>
    </welcome-file-list>

WelcomeServlet.java

package edu.pdsu.shop.servlet;

import edu.pdsu.shop.pojo.CarGoods;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * 使用Session mybatis jsp servlet EL JSTL  AJAX JQuery模拟购物车功能的实现
 * 欢迎页(欢迎页中创建购物车对象存储到session中)
 */
@WebServlet("/welcome")
public class WelComeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        //将购物车写到这里是为了防止进入到shoplist中用户刷新，购物车置空的情况
        //当下面的这段构建购物车的代码写到showlist->对应的servlet中，如果刷新页面，那么showlist->servlet会在次执行，重新创建List集合，购物车会置空
        List<CarGoods> carGoodsList = new ArrayList<>();
        //将购物车所有的实体商品存入Session中,
        HttpSession session = request.getSession();
        session.setAttribute("carGoodsList",carGoodsList);
        //重定向
        response.sendRedirect(request.getContextPath() + "/showlist");
    }
}

ShopServlet.java(负责获取所有商品的数据并传到前端进行数据展示)

package edu.pdsu.shop.servlet;

import edu.pdsu.shop.pojo.CarGoods;
import edu.pdsu.shop.pojo.goods;
import edu.pdsu.shop.service.ShopService;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

/**
 * 展示商品页servlet
 */
@WebServlet("/showlist")
public class ShopServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        //创建service对象
        ShopService service = new ShopService();
        //调用服务
        List<goods> goodss = service.showShopListService();
        //转发
        request.setAttribute("goodss",goodss);
        request.getRequestDispatcher("/shoplist.jsp").forward(request,response);
    }
}

BeforeCarServlet.java(在跳转到购物车界面前需要进行的操作 , 同时将数据传入前端进行展示)

package edu.pdsu.shop.servlet;

import edu.pdsu.shop.exception.UpdateErrorException;
import edu.pdsu.shop.pojo.CarGoods;
import edu.pdsu.shop.pojo.goods;
import edu.pdsu.shop.service.ShopService;
import edu.pdsu.shop.util.SqlSessionUtil;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import org.apache.ibatis.session.SqlSession;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * 在展示购物车(shopcar.jsp)之前需要进行判断
 *      如果购物车中包含某类商品，则此类商品购买数量加一
 *      否则购物车中新增此商品的记录
 */
@WebServlet("/beforeCar")
public class BeforeCarServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();

        //创建service方法
        ShopService service = new ShopService();
        //拿到前端传来的数据
        String[] buys = request.getParameterValues("buy");
        //获取购物车信息
        HttpSession session = request.getSession();
        List<CarGoods> carGoodsList = (List<CarGoods>) session.getAttribute("carGoodsList");
        if (buys != null ) {
            boolean flag = false;
            for (String buy : buys) {
                if (carGoodsList.isEmpty()) {
                    goods goods = service.selectByGoodsNameService(buy);
                    CarGoods carGoods2 = new CarGoods();
                    carGoods2.setCarGoodsName(goods.getGoodsName());
                    carGoods2.setCarGoodsDes(goods.getGoodsDes());
                    carGoods2.setBuyCount(1);
                    try {
                        //更新商品库存服务
                        service.updateGoodsCountservice(buy);
                        //设置购物车中商品的价格
                        carGoods2.setCarGoodsPrice(goods.getGoodsPrice());
                        carGoodsList.add(carGoods2);


                    } catch (UpdateErrorException e) {
                        out.print(e.getMessage());
                    }
                } else {
                    for (int i = 0; i < carGoodsList.size(); i++) {
                        if (carGoodsList.get(i).getCarGoodsName().equals(buy)) {
                            //购物车中有用户想要购买的商品,将购物车中的商品数量加1
                            carGoodsList.get(i).setBuyCount(carGoodsList.get(i).getBuyCount() + 1);
                            //更新商品的库存
                            try {
                                service.updateGoodsCountservice(buy);
                            } catch (UpdateErrorException e) {
                                e.printStackTrace();
                            }
                            flag = true;
                        }
                    }
                    if (flag == false) {
                        //购物车中没有此商品，将购物车中加入此商品
                        goods goods = service.selectByGoodsNameService(buy);
                        CarGoods carGoods = new CarGoods();
                        carGoods.setCarGoodsName(goods.getGoodsName());
                        carGoods.setCarGoodsDes(goods.getGoodsDes());
                        carGoods.setBuyCount(1);
                        try {
                            //更新数据库中的数据信息
                            service.updateGoodsCountservice(buy);

                            carGoods.setCarGoodsPrice(goods.getGoodsPrice());
                            carGoodsList.add(carGoods);
                        } catch (UpdateErrorException e) {
                            e.printStackTrace();
                        }


                    }
                    //重新设置flag的值为false
                    flag = false;

                }
            }
            //更新购物车的信息
            double money = 0;
            for (int i = 0; i < carGoodsList.size(); i++) {
                double carGoodsPrice = carGoodsList.get(i).getCarGoodsPrice();
                int buyCount = carGoodsList.get(i).getBuyCount();
                money += carGoodsPrice * buyCount;
            }
            HttpSession session1 = request.getSession();
            session1.setAttribute("money", money);
            request.setAttribute("carGoodsList", carGoodsList);
            //转发到购物车界面
            request.getRequestDispatcher("/shopcar.jsp").forward(request, response);

        } else {
            //更新购物车的信息
            request.setAttribute("carGoodsList", carGoodsList);
            //转发到购物车界面
            request.getRequestDispatcher("/shopcar.jsp").forward(request, response);
        }

    }
}

CarServlet.java(购物车删除功能实现)

package edu.pdsu.shop.servlet;

import edu.pdsu.shop.exception.UpdateErrorException;
import edu.pdsu.shop.pojo.CarGoods;
import edu.pdsu.shop.pojo.goods;
import edu.pdsu.shop.service.ShopService;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

/**
 * 购物车小程序
 *      购物车删除功能的实现
 */
@WebServlet("/deleteCarGoods")
public class CarServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        ShopService service = new ShopService();
        //获取前端传来的参数
        String carGoodsName = request.getParameter("carGoodsName");

        //获取session存储域中的购物车List
        HttpSession session = request.getSession();
        List<CarGoods> carGoodsList = (List<CarGoods>) session.getAttribute("carGoodsList");
        //遍历CarGoods集合

        Iterator it = carGoodsList.iterator();
        while(it.hasNext()){
            CarGoods carGoods = (CarGoods) it.next();
            if(carGoods.getCarGoodsName().equals(carGoodsName)){
                //在集合中找到要删除的商品,删除商品
                it.remove();
                //删除后还需要更新数据库中的商品库存数量
                int buyCount = carGoods.getBuyCount();
                goods good = service.selectByGoodsNameService(carGoodsName);
                good.setGoodsCount(good.getGoodsCount() + buyCount);
                try {
                    service.AddGoodsCountService(good);
                } catch (UpdateErrorException e) {
                    e.printStackTrace();
                }
                break;
            }
        }
        //更新购物车的信息
        //删除购物车中的商品的时候，商品的总价格是需要改变的
        double money = 0;
        for (int i = 0; i < carGoodsList.size(); i++) {
            double carGoodsPrice = carGoodsList.get(i).getCarGoodsPrice();
            int buyCount = carGoodsList.get(i).getBuyCount();
            money += carGoodsPrice * buyCount;
        }


        request.setAttribute("money",money);
        request.getRequestDispatcher("/shopcar.jsp").forward(request,response);


    }
}

JudgeCarServlet.java(此处主要用于AJAX异步请求判断购物车状态,具体实现可以参考shoplist.jsp)

package edu.pdsu.shop.servlet;

import edu.pdsu.shop.pojo.CarGoods;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

/**
 * 使用Ajax请求判断购物车是否为空
 *      如果为空想前端响应为空的信息（“购物车为空”）
 */
@WebServlet("/judgecar")
public class JudgeCarServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        HttpSession session = request.getSession();
        List<CarGoods> carGoodsList = (List<CarGoods>)session.getAttribute("carGoodsList");
        if(carGoodsList.isEmpty()){
            out.print("购物车为空");
        }
    }
}