简单工厂实现

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());
}
}

/// <summary>
/// 计算器抽象类
/// </summary>
public abstract class Calculation
{
public int Num1 { get; set; }
public int Num2 { get; set; }
//抽象计算方法
public abstract int CalculationMethod();
}

/// <summary>
/// 加法类abstractCalculation
/// </summary>
public class JiaFa : Calculation {

public override int CalculationMethod()
{
return Num1 +Num2 ;
}
}

/// <summary>
/// 减法类abstractCalculation
/// </summary>
public class JianFa : Calculation
{

public override int CalculationMethod()
{
return Num1 - Num2;
}
}

/// <summary>
/// 实现类（实现加减乘除）
/// </summary>
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");
}
}
}
}