using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 简单工厂{    class Program    {        static void Main(string[] args)        {           Calculation Fu =  Realization.CreateInstance("+");           Fu.Num1 = 1;           Fu.Num2 = 2;           Console.WriteLine(Fu.CalculationMethod());        }    }    /// 
    /// 计算器抽象类    /// 
    public abstract class Calculation    {        public int Num1 { get; set; }        public int Num2 { get; set; }        //抽象计算方法        public abstract int CalculationMethod();    }    /// 
    /// 加法类abstractCalculation    /// 
    public class JiaFa : Calculation {        public override int CalculationMethod()        {            return Num1 +Num2 ;        }    }    /// 
    /// 减法类abstractCalculation    /// 
    public class JianFa : Calculation    {        public override int CalculationMethod()        {            return Num1 - Num2;        }    }    /// 
    /// 实现类（实现加减乘除）    /// 
    public class Realization    {        public static Calculation CreateInstance(string operate)        {            switch (operate)            {                case "+":                    return new JiaFa();                case "-":                    return new JianFa();                default:                    throw new Exception("无效操作");            }        }    }}