策略模式

策略模式跟简单工厂模式大致相同，不同的是策略模式中的上下文类会包含策略父类。

代码1：策略抽象部分

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 策略模式
{

    /// <summary>
    /// 现金收取父类
    /// </summary>
    abstract class BaseCash
    {
        //抽象方法：收取现金，参数为原价，返回为当前价
        public abstract double acceptCash(double money);
    }

    /// <summary>
    /// 打折
    /// </summary>
    class RebateCash : BaseCash
    {
        private double moneyRebate = 1d;

        //初始化时，必需要输入折扣率,如八折，就是0.8
        public RebateCash(string moneyRebate)
        {
            this.moneyRebate = double.Parse(moneyRebate);
        }

        public override double acceptCash(double money)
        {
            return money * moneyRebate;
        }
    }

    /// <summary>
    /// 正常收费
    /// </summary>
    class NormalCash : BaseCash
    {
        public override double acceptCash(double money)
        {
            return money;
        }
    }

    //返利收费，继承CashSuper
    class ReturnCash : BaseCash
    {
        private double moneyCondition = 0.0d;
        private double moneyReturn = 0.0d;
        //初始化时必须要输入返利条件和返利值，比如满300返100，则moneyCondition为300，moneyReturn为100
        public ReturnCash(string moneyCondition, string moneyReturn)
        {
            this.moneyCondition = double.Parse(moneyCondition);
            this.moneyReturn = double.Parse(moneyReturn);
        }

        public override double acceptCash(double money)
        {
            double result = money;
            //若大于返利条件，则需要减去返利值
            if (money >= moneyCondition)
                result = money - Math.Floor(money / moneyCondition) * moneyReturn;

            return result;
        }
    }

    
}

代码2：策略容器部分

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 策略模式
{
    //现金收取工厂
    class CashContext
    {
        BaseCash cs = null;

        //根据条件返回相应的对象
        public CashContext(string type)
        {
            switch (type)
            {
                case "正常收费":
                    NormalCash cs0 = new NormalCash();
                    cs = cs0;
                    break;
                case "满300返100":
                    ReturnCash cr1 = new ReturnCash("300", "100");
                    cs = cr1;
                    break;
                case "打8折":
                    RebateCash cr2 = new RebateCash("0.8");
                    cs = cr2;
                    break;
            }
        }

        public double GetResult(double money)
        {
            return cs.acceptCash(money);
        }
    }
}