shoppingcart.java

用java编写的一个简单的购书系统

package SCartClass;
import BookClass.BookDetail;
import CItemClass.ShoppingCartItem;
import java.util.*;
import java.lang.Math;

public class ShoppingCart
{
	private HashMap items=null;
	private int numberOfItems=0;
	
	public ShoppingCart()
	{
		items=new HashMap();
	}
	
	//把书放入购物车
	public synchronized void add(String BNum,BookDetail book)
	{
		if(items.containsKey(BNum)){
			ShoppingCartItem scitem=(ShoppingCartItem)items.get(BNum);
			scitem.incrementQuantity();
			System.out.println("in add,quantity is"+scitem.getQuantity());
		}else{
			ShoppingCartItem newItem=new ShoppingCartItem(book);
			items.put(BNum,newItem);
			System.out.println("in add,quantity is"+newItem.getQuantity());
		}
	}
	
	//从购物车中删除一本书
	public synchronized void remove(String BNum)
	{
		if(items.containsKey(BNum)){
			ShoppingCartItem scitem=(ShoppingCartItem)items.get(BNum);
			scitem.decrementQuantity();
			
			if(scitem.getQuantity()<=0){
				items.remove(BNum);
			}
			
			numberOfItems--;
		}
	}
	
	//列出购物车中所有物品列表
	public synchronized List getItems()
	{
		List results=new ArrayList();
		Iterator items=this.items.values().iterator();
		
		while(items.hasNext()){
			results.add(items.next());
		}
		
		return(results);
	}
	
	
	/*
	//
	protected void finalize()throws Throwable{
		items.clear();
	}
	*/
	
	
	//购物车物品数
	public synchronized int getNumberOfItems()
	{
		numberOfItems=0;
		/*==================================================
		List results=new ArrayList();
		Iterator items=this.items.values().iterator();
		while(items.hasNext()){
			results.add(items.next());
		}*/
		for(Iterator i=getItems().iterator();i.hasNext();){
			ShoppingCartItem item=(ShoppingCartItem)i.next();
			numberOfItems+=item.getQuantity();
			System.out.println("number of items is"+numberOfItems);
		}
		return numberOfItems;
	}
	
	//购物车物品总价格
	public synchronized double getTotal()
	{
		double amount=0.0;
			/*==================================================
		List results=new ArrayList();
		Iterator items=this.items.values().iterator();
		while(items.hasNext()){
			results.add(items.next());
		}*/
		
		for(Iterator i=getItems().iterator();i.hasNext();){
			ShoppingCartItem item=(ShoppingCartItem)i.next();
			BookDetail bookDetail=(BookDetail)item.getItem();
			amount+=(bookDetail.getBPrice()*item.getQuantity());
		}
		return roundOff(amount);
	}
	
	//------------------------------------以后代码出错可能与下面这段代码有关，原来x是double类型的
	private double roundOff(double x)
	{
		//double ran=x*100;
		double  val=Math.round(x*100);
		return (val/100.0);
	}
	
	//清空购物车
	public synchronized void clear()
	{
		System.out.println("Clearing cart.");
		items.clear();
		numberOfItems=0;
	}
	
	/*
	public static void main(String []args)
	{
		ShoppingCart sc=new ShoppingCart();
		BookDBAO bk=new BookDBAO("sss","www","wwwwww",12.0,"good",20)
		sc.add()
	}*/
}