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【設計模式】【策略模式 打折算法】
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public interface DiscountStrategy
{
//定義一個用於計算打折價的方法
double getDiscount(double originPrice);
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
//實現DiscountStrategy接口，實現對VIP打折的算法
public class VipDiscount
implements DiscountStrategy
{
//重寫getDiscount()方法，提供VIP打折算法
public double getDiscount(double originPrice)
{
System.out.println("使用VIP折扣...");
return originPrice * 0.5;
}
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class OldDiscount
implements DiscountStrategy
{
//重寫getDiscount()方法，提供舊書打折算法
public double getDiscount(double originPrice)
{
System.out.println("使用舊書折扣...");
return originPrice * 0.7;
}
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class DiscountContext
{
//組合一個DiscountStrategy對象
private DiscountStrategy strategy;
//構造器，傳入一個DiscountStrategy對象
public DiscountContext(DiscountStrategy strategy)
{
this.strategy = strategy;
}
//根據實際所使用的DiscountStrategy對象得到折扣價
public double getDiscountPrice(double price)
{
//如果strategy為null，係統自動選擇OldDiscount類
if (strategy == null)
{
strategy = new OldDiscount();
}
return this.strategy.getDiscount(price);
}
//提供切換算法的方法
public void changeDiscount(DiscountStrategy strategy)
{
this.strategy = strategy;
}
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class StrategyTest
{
public static void main(String[] args)
{
//客戶端沒有選擇打折策略類
DiscountContext dc = new DiscountContext(null);
double price1 = 79;
//使用默認的打折策略
System.out.println("79元的書默認打折後的價格是："
+ dc.getDiscountPrice(price1));
//客戶端選擇合適的VIP打折策略
dc.changeDiscount(new VipDiscount());
double price2 = 89;
//使用VIP打折得到打折價格
System.out.println("89元的書對VIP用戶的價格是："
+ dc.getDiscountPrice(price2));
}
}
最後更新：2017-04-04 07:03:38