用jsp实现一个简单的购物车web应用系统。实现的添加购物商品，删除购物商品并且显示购物车信息。

1. 在自己建立的WEB工程中,建立包shopcart.dto,在相应的包中添加类Product.java ,ShopCart.java

 /*类Product */
package shopcart.dto;
import java.io.Serializable;
public class Product implements Serializable
{
    private String id;//产品标识 
    private String name;//产品名称 
    private String description;//产品描述 
    private double price;//产品价格 
    public Product()
    {
    }
    public Product(String id, String name, String description, double price)
    {
        this.id = id;
        this.name = name;
        this.description = description;
        this.price = price;
    }
    public void setId(String id)
    {
        this.id = id;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public void setDescription(String description)
    {
        this.description = description;
    }
    public void setPrice(double price)
    {
        this.price = price;
    }
    public String getId()
    {
        return id;
    }
    public String getName()
    {
        return name;
    }
    public String getDescription()
    {
        return description;
    }
    public double getPrice()
    {
        return price;
    }
}
/*类ShopCart */
package shopcart.dto;
import java.io.Serializable;
import java.util.*;
public class ShopCart implements Serializable
{
    public ShopCart()
    {
    }
    private List cart = null;
    /**
     * 添加一个产品到购物车
     * @param product Product
     */
    public void addProductToCart(Product product)
    {
        if (cart == null)
            cart = new ArrayList();
        Iterator it = cart.iterator();
        while (it.hasNext())
        {
            Product item = (Product) it.next();
            if (item.getId().equals(product.getId()))
            {
                return;
            }
        }
        cart.add(product);
    }
    /**
     * 从购物车中删除一产品
     * @param productId String 产品id
     */
    public void removeProductFromCart(String productId)
    {
        if (cart == null)
            return;
        Iterator it = cart.iterator();
        while (it.hasNext())
        {
            Product item = (Product) it.next();
            if (item.getId().equals(productId))
            {
                it.remove();
                return;
            }
        }
    }
    /**
     * 计算购物车中的商品价格
     * @return double 商品价格总数
     */
    public double getAllProductPrice()
    {
        if (cart == null)
            return 0;
        double totalPrice = 0;
        Iterator it = cart.iterator();
        while (it.hasNext())
        {
            Product item = (Product) it.next();
            totalPrice += item.getPrice();
        }
        return totalPrice;
    }
    /**
     * 返回购物车所有产品信息
     * @return List
     */
    public List getAllProductsFromCart()
    {
        return cart;
    }
}
 

2.在WebRoot目录下添加包shopCart 在里边添加ShowProductsJSP.jsp ShoppingJSP.jsp ShopCartJSP.jsp

ShowProductsJSP.jsp :::::::::

 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ page import="shopcart.dto.*"%>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://"
            + request.getServerName() + ":" + request.getServerPort()
            + path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <base href="<%=basePath%>">
        <title>My JSP 'ShowProductsJSP.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" type="text/css" href="styles.css">
    -->
    </head>
    <body bgcolor="#ffffff">
        <%
            Map products = new HashMap();
            products.put("001", new Product("001", "mp3播放器",
                    "效果很不错的mp3播放器，存储空间达1GB", 999.00));
            products.put("002", new Product("002", "数码相机", "象素500万，10倍光学变焦",
                    2500.00));
            products.put("003", new Product("003", "数码摄像机",
                    "120万象素，支持夜景拍摄，20倍光学变焦", 5999.00));
            products.put("004", new Product("004", "迷你mp4",
                    "市面所能见到的最好的mp4播放器，国产", 1999.99));
            products.put("005", new Product("005", "多功能手机",
                    "集mp3播放、100万象素数码相机，手机功能于一体", 2199.99));
            ServletContext context = getServletContext();
        context.setAttribute("products", products);
        %>
        <H1>
            产品显示
        </H1>
        <a href="/helloApp/shopCart/ShowCartJSP.jsp">查看购物车</a>
        <form name="productForm" action="/helloApp/shopCart/ShoppingJSP.jsp" method="POST">
            <input type="hidden" name="action" value="purchase">
            <table border="1" cellspacing="0">
                <tr bgcolor="#CCCCCC">
                <tr bgcolor="#CCCCCC">
                    <td>
                        序号
                    </td>
                    <td>
                        产品名称
                    </td>
                    <td>
                        产品描述
                    </td>
                    <td>
                        产品价格（￥）
                    </td>
                    <td>
                        添加到购物车
                    </td>
                </tr>
                <%
                    Set productIdSet = products.keySet();
                    Iterator it = productIdSet.iterator();
                    int number = 1;
            
                    while (it.hasNext()) {
                        String id = (String) it.next();
                        Product product = (Product) products.get(id);
                        %><tr>
                    <td>
                        <%=number++ %></td>
                    <td>
                        <%=product.getName()%>
                    </td>
                    <td><%=product.getDescription() %>
                    </td>
                    <td>
                        <%=product.getPrice() %></td>
                    <td>
                        <input type="checkbox" name="productId"
                            value="<%=product.getId() %>">
                    </td>
                </tr>
                    <% }%>
            </table>
            <p>
                <input type="reset" value="全部取消" />
                <input type="submit" value="确定" />
            </p>
        </form>
    </body>
</html>
 

ShoppingJSP.jsp::::::::::

 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ page import="shopcart.dto.*"%>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://"
            + request.getServerName() + ":" + request.getServerPort()
            + path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <base href="<%=basePath%>">
        <title>My JSP 'shopping.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" type="text/css" href="styles.css">
    -->
    </head>
    <body bgcolor="#ffffff">
        <%
            try{
            response.setContentType("text/html; charset=GBK");
            HttpSession mysession = request.getSession();
            ServletContext context = getServletContext();
            ShopCart cart = (ShopCart) mysession.getAttribute("shopCart");
            String action = request.getParameter("action");
            if ("remove".equals(action)) {
                String removeId = request.getParameter("removeId");
                cart.removeProductFromCart(removeId);
            } else if(action.equals("purchase")){
                String[] productIds = request.getParameterValues("productId");
                Map products = (Map) context.getAttribute("products");
                if (cart == null) {
                    cart = new ShopCart();
                    mysession.setAttribute("shopCart", cart);
                }
                if (productIds == null) {
                    productIds = new String[0];
                }
                for (int i = 0; i < productIds.length; i++) {
                    Product product = (Product) products.get(productIds[i]);
                    cart.addProductToCart(product);
                }
            }
            }catch(NullPointerException e)
            {e.printStackTrace();}
        %>
        <jsp:forward page="/shopCart/ShowCartJSP.jsp"></jsp:forward>
    </body>
</html>
 

ShopCartJSP.jsp:::::::::

 <%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ page import="shopcart.dto.*" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'ShowCartJSP.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" type="text/css" href="styles.css">
    -->
  </head>
  
  <body><% 
  HttpSession mysession = request.getSession();
        ShopCart cart = (ShopCart) mysession.getAttribute("shopCart");
    List products = null;
            if (cart == null
                    || (products = cart.getAllProductsFromCart()) == null) {
        %>
        
        <h1>
            你目前没有购买任何产品
        </h1>
        
        <p>
            <a href="/shopCart/ShowProductsJSP.jsp">返回产品显示页</a>
        </p>
        <%
            } else {
                Iterator iterator = products.iterator();
        %>
        
        <h1>
            你目前购买的产品为：
        </h1>
        
        <table border="1" cellspace="0">
            <tr bgcolor="#CCCCCC">
                <td>
                    产品名称
                </td>
                <td>
                    产品描述
                </td>
                <td>
                    价格
                </td>
                <td>
                    操作
                </td>
            </tr>
            <%
                while (iterator.hasNext()) {
                        Product productItem = (Product) iterator.next();
            %>
            <tr>
                <td>
                    <%=productItem.getName()%>
                </td>
                <td><%=productItem.getDescription()%>
                </td>
                <td>
                    <%=productItem.getPrice()%></td>
                <td>
                    <a
                        href="/helloApp/shopCart/ShoppingJSP.jsp?action=remove&removeId=<%=productItem.getId()%>">删除</a>
                </td>
            </tr>
            <%
                }
            %>
        </table>
        <p>
            目前您购物车的总价格为：<%=cart.getAllProductPrice()%>
            元人民币。
        </p>
        <p>
            </br>
            <a href="/helloApp/shopCart/ShowProductsJSP.jsp">返回产品显示页</a>
        </p>
        <%
            }
        %>
  </body>
</html>
 