策略模式(Strategy Pattern):定义一系列算法类,将每一个算法封装起来,并让它们可以相互替换,策略模式让算法独立于使用它的客户而变化,也称为政策模式(Policy)。
模式角色与结构:
示例代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text; namespace CSharp.DesignPattern.StrategyPattern
{
class Program
{
static void Main(string[] args)
{
MovieTicket mt = new MovieTicket();
double originalPrice = 60.0;
double currentPrice; mt.Price = originalPrice; IDiscount discount = new StudentDiscount(); // 也可以用配置文件和反射创建新的对象
mt.Discount = discount; // 注入折扣对象 currentPrice = mt.GetCurrentPrice();
Console.Write("student price: " + currentPrice.ToString());
}
} // 环境类
class MovieTicket
{
public double GetCurrentPrice()
{
return _discount.calculate(this._price);
} public double Price
{
get { return _price; }
set { _price = value; }
} public IDiscount Discount
{
set { _discount = value; }
} private double _price;
private IDiscount _discount; // 维持一个对抽象策略类的引用
} // 抽象策略类
interface IDiscount
{
double calculate(double price);
} // 具体策略类
class StudentDiscount : IDiscount
{
public double calculate(double price)
{
return price * 0.8;
}
} // 具体策略类
class ChildrenDiscount : IDiscount
{
public double calculate(double price)
{
return price - ;
}
} // 具体策略类
class VIPDiscount : IDiscount
{
public double calculate(double price)
{
return price * 0.5;
}
}
}