购物车的数据结构问题

[xjpcj]

小弟想做个购物网，可是在购物车的结构设计上碰到了麻烦。望各位大侠相助！
public class ShopCart {
private HashMap<String, Product> hashMap;\\\\\\\\\\\\商品编号，商品类的hashMap

public HashMap<String, Product> getHashMap() {
return hashMap;
}

public void setHashMap(HashMap<String, Product> hashMap) {
this.hashMap = hashMap;
}

@SuppressWarnings("unchecked")
public ShopCart(){
hashMap = new HashMap();
}\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\其他代码省略。

在购物网中 ，用户如果要购买的商品数量大于1以上，那使用hashMap并没有办法表示，如果在Product类中增加一个数量的属性那缺陷就太大了，最好是有什么数据结构能直接表示的？小弟觉得在ShopCart里面弄个内部类比较好。不知道做过购物网的朋友是怎么设计它的？

[xjpcj]

二楼的朋友意见挺好，四楼的朋友OrderLine类是不是包含了商品类和数量的属性？

[lcj_up]

是的。。。。

[money8899]

google

[ouwarmth]

之前做过，但我用的数据结构是：HashMap <int, int>。第一个int类型储存的是商品的Id号，唯一的；第二个int类型可以用来储存对应商品的数量。这样就可以实现楼主想要的结果了。

[tuyan123]

package com.shopping.impl;

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import com.shopping.cart.Cart;
import com.shopping.pojo.ProductItemVO;
import com.shopping.pojo.ProductVO;
//购物车
public class CartImpl implements Cart {
	
	private Map<String, ProductItemVO> cart = Collections.synchronizedMap(new HashMap<String, ProductItemVO>());	

	public void addItem(ProductVO product) {
		
		String key = product.getPpid();
		ProductItemVO item = cart.get(key);
		if (item == null){
			item = new ProductItemVO();
			item.setProduct(product);
			item.setQuantity(1);
			cart.put(key, item);
		}else{
			item.incrementQuantity();
		}
	}
	
	public void incrementQuantity(String key){
		ProductItemVO item = cart.get(key);
		item.incrementQuantity();
	}
	
	public void setQuantity(String key, int quantity){
		ProductItemVO item = cart.get(key);
		item.setQuantity(quantity);
	}

	public void clear() {
		cart.clear();
	}

	public void removeItem(String index) {
		cart.remove(index);
	}
	
	public double getTotalMoney(){
		double totalMoney = 0.0;
		for (Iterator<ProductItemVO> iter = cart.values().iterator(); iter.hasNext(); ){
			ProductItemVO item = iter.next();
			totalMoney = totalMoney + item.getTotalPrice();
		}
		return totalMoney;
	}
	
	public Map<String, ProductItemVO> getCart() {
		return cart;
	}

	public int getAmount() {
		// TODO Auto-generated method stub
		int amount = 0;
		for (Iterator<ProductItemVO> iter = cart.values().iterator(); iter.hasNext(); ){
			
			ProductItemVO item = iter.next();
			
			amount = amount + item.getQuantity();
		}
		
		return amount;
	}

	public boolean hasItem(String key) {
		// TODO Auto-generated method stub
		return cart.containsKey(key);
	}
}


//商品枚举
package com.shopping.pojo;

import java.io.Serializable;

public class ProductItemVO implements Serializable{
	
	/**
	 * 此商品枚举中的商品
	 */
	private ProductVO product;
	
	/**
	 * 此商品枚举中的相应商品的数量
	 */
	private int quantity;
	
	public ProductVO getProduct() {
		return product;
	}
	public void setProduct(ProductVO product) {
		this.product = product;
	}
	public int getQuantity() {
		return quantity;
	}
	public void setQuantity(int quantity) {
		this.quantity = quantity;
	}
	/**
	 * 商品数量的增加
	 */
	public void incrementQuantity(){
		quantity++;
	}
	/**
	 * 商品价格
	 * @return
	 */
	public double getTotalPrice() {
		if (product != null) {
			return product.getPrice() * quantity;
		}else {
			return 0;
		}
	}
}

[lcj_up]

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class ShopCart {

private Map items = new HashMap();


public void add(OrderLine line) {
Integer product_id = line.getProduct().getId();
OrderLine orderLine = (OrderLine) items.get(product_id);
if (orderLine == null) {
items.put(product_id, line);
} else {
orderLine.setAmount(orderLine.getAmount() + line.getAmount());
items.put(product_id, orderLine);
}
}



public void remove(OrderLine line) {
Integer product_id = line.getProduct().getId();
items.remove(product_id);
}

public void remove(Integer id) {
items.remove(id);
}


public void modify(OrderLine line) {
Integer product_id = line.getProduct().getId();
items.put(product_id, line);
}

public double getTotal() {
double total = 0;
Set set = items.keySet();
Iterator it = set.iterator();
while (it.hasNext()) {
Integer id = (Integer) it.next();
OrderLine line = (OrderLine) items.get(id);
total += line.getProduct().getBasePrice() * line.getAmount();
}
return total;
}


public int getCount() {
int count = 0;
Set set = items.keySet();
Iterator it = set.iterator();
while (it.hasNext()) {
Integer id = (Integer) it.next();
OrderLine line = (OrderLine) items.get(id);
count += line.getAmount();
}
return count;
}


public int getSize() {
return items.size();
}


public Order getOrder() {
Order order = new Order();
Set set = new HashSet();
Collection list = items.values();
set.addAll(list);
order.setOrderlines(set);
return order;
}


public void clearCart() {
items.clear();
}

public Map getItems() {
return items;
}

public void setItems(Map items) {
this.items = items;
}

}