一个小型的购物商店

				/*				 * Cart.java				 *				 * Created on 2006年9月14日, 下午2:11				 *				 * To change this template, choose Tools | Template Manager				 * and open the template in the editor.				 */								package com.shopping.model;				import java.util.*;								/**				 *				 * @author 曹昊				 */				public class Cart {				    				    private Map items = new HashMap();				    private double cost = 0.0;//总价格				    				    public Cart(){}				    				    public void addItem(Item item){				        items.put(item.getProduct().getId()+"",item);				    }				    				    public void modifyNumberByProductId(String productId, int number){				        Item item = (Item)items.get(productId);				        item.setNumber(number);				        item.incrementCost();				    }				    				    public void deleteItemByProductId(String productId){				        items.remove(productId);				    }				    				    public void deleteItemsByProductId(String[] productId){				        for(int i = 0; i< productId.length; i++){				            items.remove(productId[i]);				        }				    }				    				    public double getCost(){				        cost = 0.0;				        Iterator it = items.values().iterator();				        while(it.hasNext()){				            Item item = (Item)it.next();				            cost += item.getCost();				        }				        return cost;				    }				    				    public void setCost(double cost){				        this.cost = cost;				    }				    				    public void clear(){				        if(items != null){				            items.clear();				        }				        setCost(0.0);				    }				    				    public Map getItems(){				        return this.items;				    }				    				    public boolean isEmpty(){				        return items.size() == 0;				    }				    				}