20.策略者模式(Stragety Pattern)

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

namespace ConsoleApplication3
{
    /// <summary>
    /// 策略模式是针对一组算法，将每个算法封装到具有公共接口的独立的类中，
    /// 从而使它们可以相互替换。策略模式使得算法可以在不影响到客户端的情况下发生变化。
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            // 个人所得税方式
            InterestOperation operation = new InterestOperation(new PersonalTaxStrategy());
            Console.WriteLine("个人支付的税为：{0}", operation.GetTax(5000.00));

            // 企业所得税
            operation = new InterestOperation(new EnterpriseTaxStrategy());
            Console.WriteLine("企业支付的税为：{0}", operation.GetTax(50000.00));
            Console.Read();
        }
    }

    // 所得税计算策略
    public interface ITaxStragety
    {
        double CalculateTax(double income);
    }


    // 个人所得税
    public class PersonalTaxStrategy : ITaxStragety
    {
        public double CalculateTax(double income)
        {
            return income * 0.12;
        }
    }

    // 企业所得税
    public class EnterpriseTaxStrategy : ITaxStragety
    {
        public double CalculateTax(double income)
        {
            return (income - 3500) > 0 ? (income - 3500) * 0.045 : 0.0;
        }
    }

    /// <summary>
    /// 选择方法
    /// </summary>
    public class InterestOperation
    {
        private ITaxStragety m_strategy;
        public InterestOperation(ITaxStragety strategy)
        {
            this.m_strategy = strategy;
        }

        public double GetTax(double income)
        {
            return m_strategy.CalculateTax(income);
        }
    }
}