CartServlet参考代码 :
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String bookids[] = req.getParameterValues("bookId"); //id数组;
Map<Integer,Book> cart = (Map<Integer,Book>)req.getSession().getAttribute("cart");
//System.out.println(cart.size()); null对
/*
* Integer Book
* id book (count)
* 7 book （count=2）
* 8 book ( count=5)
*
* */
BookDao bd = new BookDaoImpl();
//如果购物车为null，则new出来一个HashMap对象
if(cart==null){
cart = new HashMap<Integer,Book>();//id以及book对象
req.getSession().setAttribute("cart", cart);
}
for(String bookid:bookids){
Book book = cart.get(Integer.parseInt(bookid));
if(book==null){
book = bd.findById(Integer.parseInt(bookid));//根据id获得书籍
book.setCount(1);//数量为1
}
else{
// 判断是否已经是最后一本书;数量大于获得数量,其他的不能再加数量了
if(book.getStock()>book.getCount()){
book.setCount(book.getCount()+1);
}
}
cart.put(Integer.parseInt(bookid), book);
//需要放入到数据库中,那么购物车表的字段是什么呢？
//图书id 书名 图片名 数量 合计价格
}
req.getSession().setAttribute("cart", cart);
resp.sendRedirect("cart.jsp");
}在该Servlet中利用了session进行存放值，就是开篇我们的方法之一，但是这种方法有什么问题呢？大家好好思考下！！！
下面是购物车代码参考：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'cart.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<link rel="stylesheet" href="css/style.css" type="text/css"></link>
<script type="text/javascript" src="js/jquery-1.7.2.min.js"></script>
<script type="text/javascript">
function jian(id){
if($("#count"+id).val()==1){
//采用淘宝模式，如果低于1，则不用提示，直接不可用;
$("#count"+id).prev().attribute("disabled","disabled");
return;
}
$.ajax({
url:'ChangeCartCountServlet',
type:'post',
dataType:'text',
data:{
bookid:id,
count:parseInt($("#count"+id).val())-1 // -1
},
success:function(data){
var price = $("#price"+id).html();
$("#count"+id).val(parseInt($("#count"+id).val())-1);
$("#sum"+id).val("￥"+price*$("#count"+id).val());
calcTotal();
}
});
}
function add(id){
$.ajax({
url:'ChangeCartCountServlet',
type:'post',
dataType:'text',
data:{
bookid:id,
count:parseInt($("#count"+id).val())+1
},
success:function(data){
if(data=="false"){
alert("库存不足!!!!");
}
else{
var price = $("#price"+id).html();
$("#count"+id).val(parseInt($("#count"+id).val())+1);
$("#sum"+id).val("￥"+price*$("#count"+id).val());
calcTotal();
}
}
});
}
function calcTotal(){
// input...
var counts = $("input[id^=count]").toArray();
var prices = $("div[id^=price]").toArray();
var total = 0;
for(var i=0;i<prices.length;i++){
total += prices[i].innerHTML*counts[i].value;
}
$("#total").val("￥"+total);
}
</script>
</head>
<body>
<div id="header" class="wrap">
<div id="banner"></div>
<div id="navbar">
<div class="userMenu">
<ul>
<li class="current"><font color="BLACK">欢迎您，<strong>andy</strong></font> </li>
<li><a href="index.html">首页</a></li>
<li><a href="orderlist.html">我的订单</a></li>
<li><a href="cart.html">购物车</a></li>
<li><a href="logout.jsp">注销</a></li>
</ul>
</div>
</div>
</div>
<div id="content" class="wrap">
<div class="list bookList">
<form method="post" name="shoping" action="BuyServlet">
<table>
<tr class="title">
<th class="view">图片预览</th>
<th>书名</th>
<th class="nums">数量</th>
<th class="price">价格</th>
<th class="nums">合计</th>
<th class="nums">操作</th>
</tr>
<c:set var="total" value="0"></c:set>
<c:forEach items="${cart}" var="book">
<tr>
<td class="thumb">
<img src="images/book/${book.value.image}" /></td>
<td class="title">${book.value.bookname}</td>
<td>
<img src="images/edit_jian.png" width="12" height="12"
οnclick="jian(${book.value.id})"/>
<input id="count${book.value.id}" readonly="readonly"
value="${book.value.count}" size="2"/>
<img src="images/edit_add.png" width="12" height="12"
οnclick="add(${book.value.id})"/>
</td>
<td>￥
<div id="price${book.value.id}" >${book.value.price}</div>
</td>
<td>
<input id="sum${book.value.id}"
value='<fmt:formatNumber
value="${book.value.count*book.value.price}"
type="currency"></fmt:formatNumber>'
/>
<c:set var="total"
value=
"${total+book.value.count*book.value.price}"></c:set>
<input type="hidden" name="items" value="10:2:31.6"/>
</td>
<td>
<a href="DeleteCartItemServlet?bookid=${book.value.id}">删除</a>
</td>
</tr>
</c:forEach>
<tr>
<td>
地址
</td>
<td colspan="5">
<input name="shipaddress">
</td>
</tr>
<tr>
<td>
电话
</td>
<td colspan="5">
<input name="contactphone">
</td>
</tr>
<tr><td colspan="5">
<div class="button">
<h4>总价：
<input id="total"
value='<fmt:formatNumber value="${total}" type="currency"></fmt:formatNumber>'
/>
元</h4>
<input type="hidden" id="hidden_total_price" name="hidden_total_price"/>
<input class="input-chart" type="submit" name="submit" value="" />
</div>
</td></tr>
</table>
</form>
</div>
</div>
</body>
<div id="footer" class="wrap">
网上书城 © 版权所有
</div>
</html>
</html>
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int bookid = Integer.parseInt(req.getParameter("bookid"));
Map<Integer,Book> cart = (Map<Integer,Book>)
req.getSession().getAttribute("cart");
// 根据key(bookid)删除
cart.remove(bookid);
req.getSession().setAttribute("cart", cart);
resp.sendRedirect("cart.jsp");
}