创建型-工厂方法factory method

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

namespace 工厂方法_计算器
{

/// <summary>
/// 运算类
/// </summary>
class Operation
{
private double _numberA = 0;
private double _numberB = 0;

public double NumberA
{
get { return _numberA; }
set { _numberA = value; }
}

public double NumberB
{
get { return _numberB; }
set { _numberB = value; }
}

/// <summary>
/// 得到运算结果
/// </summary>
/// <returns></returns>
public virtual double GetResult()
{
double result = 0;
return result;
}
}

/// <summary>
/// 加法类
/// </summary>
class OperationAdd : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA + NumberB;
return result;
}
}

/// <summary>
/// 减法类
/// </summary>
class OperationSub : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA - NumberB;
return result;
}
}
/// <summary>
/// 乘法类
/// </summary>
class OperationMul : Operation
{
public override double GetResult()
{
double result = 0;
result = NumberA * NumberB;
return result;
}
}
/// <summary>
/// 除法类
/// </summary>
class OperationDiv : Operation
{
public override double GetResult()
{
double result = 0;
if (NumberB == 0)
throw new Exception("除数不能为0。");
result = NumberA / NumberB;
return result;
}
}

/// <summary>
/// 工厂方法
/// </summary>
interface IFactory
{
Operation CreateOperation();
}

/// <summary>
/// 专门负责生产“+”的工厂
/// </summary>
class AddFactory : IFactory
{
public Operation CreateOperation()
{
return new OperationAdd();
}
}

/// <summary>
/// 专门负责生产“-”的工厂
/// </summary>
class SubFactory : IFactory
{
public Operation CreateOperation()
{
return new OperationSub();
}
}

/// <summary>
/// 专门负责生产“*”的工厂
/// </summary>
class MulFactory : IFactory
{
public Operation CreateOperation()
{
return new OperationMul();
}
}

/// <summary>
/// 专门负责生产“/”的工厂
/// </summary>
class DivFactory : IFactory
{
public Operation CreateOperation()
{
return new OperationDiv();
}
}

}

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

namespace 工厂方法_计算器
{
class Program
{
static void Main(string[] args)
{
IFactory operFactory = new AddFactory();
Operation oper = operFactory.CreateOperation();
oper.NumberA = 1;
oper.NumberB = 2;
double result=oper.GetResult();

Console.WriteLine(result);

Console.Read();
}
}
}