<a href="AddCart?id=${b.id}"><button class="btn btn-default">加入购物车<span class="glyphicon glyphicon-shopping-cart"></span></button></a>
商品详情页选中“加入购物车”后跳到AddCart
public class AddCart extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String id=request.getParameter("id");
ProductService ps=new ProductService();
Book b=ps.findBookById(id);
HttpSession session=request.getSession();
//从session中获取购物车对象
Map<Book,Integer> cart=(Map<Book,Integer>)session.getAttribute("cart");
//如果购物车为空，说明没有商品存储在购物车中，创建除购物车
if(cart==null) {
cart=new HashMap<Book,Integer>() ;
}
//向购物车添加商品数量信息
Integer count=cart.put(b, 1);
//如果商品数量不为空，则商品数量+1，否则添加新的商品信息
if(count!=null) {
cart.put(b, count+1);
}
session.setAttribute("cart", cart);
request.getRequestDispatcher("cart.jsp").forward(request, response);;
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
以map集合存储Book对象还有购买数量，并且新建购物车，存进session中
<script type="text/javascript">
function changeNum(id,num,totalCount){
num = parseInt(num);
totalCount =parseInt(totalCount);
if(num<1){
if(confirm("是否确认要删除此商品？")){
num = 0;
}else{
num=1;
}
}
if(num>totalCount){
alert("购买数量不能大于库存数量！");
num=totalCount;
}
location.href="${pageContext.request.contextPath}/ChangeNumServlet?id="+id+"&num="+num;
}
</script>
<table cellpadding="1" style="width: 80%; height: auto;border:1px #8B0000 solid;text-align:center;margin-left:150px;">
<tr>
<td width="10%"> 序号</td>
<td width="30%"> 商品名称</td>
<td width="10%">价格</td>
<td width="20%"> 数量</td>
<td width="10%">库存</td>
<td width="10%">小计</td>
<td width="10%">取消</td>
</tr>
</table>
<!-- 循环输出商品信息 -->
<c:set var="total" value="0"/>
<c:forEach items="${cart}" var="entry" varStatus="vs">
<table width="80%" border="0" cellspacing="0" style="margin-left:150px;text-align:center">
<tr>
<td width="10%">${vs.count}</td>
<td width="30%">${entry.key.name}</td>
<td width="10%">${entry.key.price }</td>
<td width="20%">
<!-- 减少商品数量 -->
、 <input type="button" value='-' style="width:20px" onclick="changeNum('${entry.key.id}','${entry.value-1 }','${entry.key.pnum }')">
<!-- 商品数量显示 -->
<input name="text" type="text" value="${entry.value}" style="width:40px;text-align:center">
<!-- 添加商品数量 -->
<input type="button" value='+' style="width:20px" onclick="changeNum('${entry.key.id}','${entry.value+1 }','${entry.key.pnum }')">
</td>
<td width="10%">${entry.key.pnum}</td>
<td width="10%">${entry.key.price*entry.value}</td>
<td width="10%">
<!-- 删除商品 -->
、 <a href="ChangeNumServlet?id=${entry.key.id}&num=0" style="color: #FF0000; font-weight: bold">X</a>
</td>
</tr>
</table>
<c:set value="${total+ entry.key.price*entry.value}" var="total"/>
</c:forEach>
<br>
<!-- 合计信息 -->
<table style="margin-left:1000px">
<tr>
<td><font style="color: #FF6600; font-weight: bold">合计： ${total}元</font>
</td>
</tr>
</table>
<br>
<br>
<br>
<div style="padding-left:690px;">
<a href="index.jsp"><button class="btn btn-info">继续购物</button></a>
<a href="order.jsp"><button class="btn btn-default">立即买单</button></a>
</div>
public class ChangeNumServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String id = request.getParameter("id");
int num = Integer.parseInt(request.getParameter("num"));
HttpSession session = request.getSession();
Map<Book, Integer> cart = (Map<Book, Integer>) session.getAttribute("cart");
ProductService ps=new ProductService();
Book b=ps.findBookById(id);
//如果商品数据为0，就删除对象
if(num==0) {
cart.clear();
}else {
cart.clear();
cart.put(b, num);
}
request.getRequestDispatcher("cart.jsp").forward(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}通过id找到对应的book对象后，从session中取出集合，要先清空集合再重新存键值（书和购买数量进去），不清空就会导致一会的cart页面出现多行从购物车里遍历取出来的数据