AddCountInCartServlet | 易学教程

package cn.itcast.estore.web.servlet;

import java.io.IOException;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.estore.domain.Product;

public class AddCountInCartServlet extends HttpServlet {

   @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       // 1.获取参数id，商品数量count
       String id = request.getParameter("id");
       String count = request.getParameter("count");
       int countInt = Integer.parseInt(count);
       // 2.获取购物车
       Map<Product, Integer> cart = (Map<Product, Integer>) request
               .getSession().getAttribute("cart");
       // 3.遍历购物车cart，判断购物车中是否有该商品
       if (cart != null) {
           for (Product p : cart.keySet()) {
               if (p.getId().equals(id)) {
                   // 4.count++ 判断是否超出库存
                   if (countInt >= p.getNum()) {
                       countInt = p.getNum();
                       request.setAttribute("add.message", "已达到库存最大值！");
                   } else {
                       countInt++;
                   }
                   // 5.将商品添加到购物车，添加到session
                   cart.put(p, countInt);
               }
           }
           // 6.将cart添加到session
           request.getSession().setAttribute("cart", cart);
           request.getRequestDispatcher("/showCart.jsp").forward(request,
                   response);
           return;
       }

}

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

}

showCart.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
   pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>购物车信息</title>
<script type="text/javascript">
   //商品id，数量，库存
   function changeCount(id, count, num) {
       //将count转换为数值型，num本身就是数字
       count = parseInt(count);
       //边界控制
       if (count > num) {
           count = num;
           alert("最大购物数量：" + num);
       } else if (count == 0) {
           count = 0
           var flag = window.confirm("确定要删除该商品吗？");
           if (flag) {
               count = 0;
           } else {
               count = 1;
           }
       }
       location.href = "${pageContext.request.contextPath}/updateCountInCart?id="
               + id + "&count=" + count;
   };

       }
   };
   //通过阻止事件的默认行为来实现控制删除
   function preventDel(e) {
       var flag = window.confirm("确定要删除商品吗"); //确定是返回ture,否返回false;
       alert(flag);
       if (!flag) {
           //不删除,阻止链接的默认行为执行。
           //阻止事件的默认行为
           //该方法是阻止事件的默认行为
           if (e && e.preventDefault) {
               //e对象存在   e.preventDefault方法存在---firfox浏览器
               e.preventDefault();
           } else {
               //不支持e对象    或者preventDefault方法不存在----IE浏览器
               window.event.returnValue = false;
           }
       }
   }
   function preventRemove(id) {
       var flag = window.confirm("是否要删除商品");
       if (flag) {
           //确定返回ture 删除商品
           location.href = "${pageContext.request.contextPath }/removeProductFromCrat?id="
                   + id;
       }
   };
</script>
</head>
<body>
   <c:if test="${empty cart }">
购物车里没有商品
</c:if>
   <c:if test="${not empty cart }">
       <br>
       <br>
       <br>
       <table border='1' align='center' width="65%">
           <caption>购物车</caption>
           <tr>
               <td>图片</td>
               <td>商品名称</td>
               <td>商品数量</td>
               <td>操作</td>
           </tr>
           <c:set var="totalMoney" value="0" />
           <c:forEach items="${cart }" var="mp">
               <tr>
                   <td><img
                       src="${pageContext.request.contextPath }${mp.key.imgurl}" alt="图片"
                       align="left" height="50" width="50" /></td>
                   <td>${mp.key.pname }</td>
                   <td>${mp.value }<span>${requestScope["add.message"]}</span>
                   </td>

                   <td><input type="button" value="-"
                       οnclick="changeCount('${mp.key.id}','${mp.value-1}')"> <input
                       type="button" value="+"
                       οnclick="changeCount('${mp.key.id}','${mp.value+1}','${mp.key.num}')">
                         可购买数量:${mp.key.num} <input type="text"
                       value="${mp.value}" size="7" style="text-align:center"
                       οnblur="changeCount('${mp.key.id}',this.value,'${mp.key.num}')"
                       οnkeydοwn="numberText(event)">
                   </td>
                   <td><a
                       href="${pageContext.request.contextPath }/removeProductFromCrat?id=${mp.key.id }"
                       οnclick="preventDel(event);">删除</a> <a href="#"
                       οnclick="preventRemove('${mp.key.id }');">删除</a> <a href="#"
                       οnclick="preventRemove('${mp.key.id }');return false;">删除</a> <a
                       href="" οnclick="preventRemove('${mp.key.id }');return false;">删除</a>

               </tr>
               <c:set var="totalMoney"
                   value=" ${totalMoney + mp.key.price * mp.value}" />
           </c:forEach>
           <tr>
               <td colspan="2" align="center">总价：</td>
               <td>${totalMoney }</td>
           </tr>
           <tr>
               <td><a href="${pageContext.request.contextPath }/order.jsp">结算</a>
               </td>
           </tr>
       </table>
   </c:if>
</body>
</html>

来源：CSDN

作者：live801

链接：https://blog.csdn.net/live801/article/details/103951415

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