package?homework6;

import?java.util.ArrayList;

class?PricingStrategyFactory{
	private?static?PricingStrategyFactory?instance;
	private?PricingStrategyFactory??（）?{}
	public?static?synchronized?PricingStrategyFactory?getInstance（）?{
		if（instance?==?null）?{
			instance?=?new?PricingStrategyFactory?（）;
		}?
		return?instance;?
	}
????public?IPricingStrategy?getPricingStrategy（int?bookType）{
????	IPricingStrategy?ips?=?null;
????	switch（bookType）?{
????	case?0:?ips?=?new?NoDiscountStrategy（）;break;
????	case?1:?ips?=?new?FlatRateStrategy（1）;break;
????	case?2:?ips?=?new?PercentageStrategy（3）;break;
????	case?3:?ips?=?new?PercentageStrategy（7）;break;
????	}
????	return?ips;
????}
}

class?ProductSpecification{
	public?String?isbn;
	public?String?title;
????public?double?price;
????public?int?type;
????public?ProductSpecification（String?s1String?s2double?dint?t）{
????	isbn=s1;?title=s2;?price=d;?type=t;
????}
????public?double?getPrice（）{
????	return?price;
????}
????public?String?toString（）{
????	return?String.format（“isbn:%-20stitle:%-20sprice:%-20stype:%-20s“?isbntitlepricetype）;
????}
}


class?SaleLineItem?{
????private?int?copies;
????private?ProductSpecification?pSpec;
????private?IPricingStrategy?strategy;
????public?SaleLineItem（int?cProductSpecification?p）{
????	copies=c;
????	pSpec=p;
????	PricingStrategyFactory?psf?=?PricingStrategyFactory.getInstance（）;
????	strategy?=?psf.getPricingStrategy（pSpec.type）;
????}
????public?void?setCopies（int?c）{copies=c;}
????public?int?getCopies（）{return?copies;}
????public?String?gettitle（）{return?pSpec.title;}
????public?String?getIsbn（）{return?pSpec.isbn;}
????public?double?getPrice（）{return?pSpec.price;}
????public?double?getSubTotal（）{return?strategy.getSubTotal（this）;}
}

interface?IPricingStrategy{
	public?int?getStrategyType（）;
	public?String?getData（）;
	public?double?getSubTotal（SaleLineItem?item）;
}

class?NoDiscountStrategy?implements?IPricingStrategy{
	public?int?strategyType=0;
	public?String?getData（）{return?“0“;}
	public?int?getStrategyType（）{return?strategyType;}
????public?double?getSubTotal（SaleLineItem?item）{
????	return?item.getPrice（）*item.getCopies（）;
???