1、抽象操作类Operation，及其具体实现类AddOperation、SubOperation

/// <summary>

/// 抽象操作类

/// </summary>

public abstract class Operation

{

    public int numberA;

    public int numberB;

    public abstract int GetResult();

}

/// <summary>

/// 加法操作

/// </summary>

public class AddOperation : Operation

{

    public override int GetResult()

    {

       return (this.numberA + this.numberB);

    }

}

/// <summary>

/// 减法操作

/// </summary>

public class SubOperation : Operation

{

    public override int GetResult()

    {

        return (this.numberA - this.numberB);

    }

}

2、抽象工厂类Factory及其具体工厂类AddFactory、SubFactory

public abstract class Factory

{

    public abstract Operation CreateOperation();

}

public class AddFactory : Factory

{

    public override Operation CreateOperation()

    {

        return new AddOperation();

    }

}

public class SubFactory:Factory

{

    public override Operation CreateOperation()

    {

        return new SubOperation();

    }

}

3、客户端代码

static void Main(string[] args)

{

    Console.WriteLine("使用工厂方法进行计算");

    Factory factory1 = new AddFactory();

    Operation operation1= factory1.CreateOperation();

    operation1.numberA = 10;

    operation1.numberB = 20;

    Console.WriteLine("{0}+{1}={2}", operation1.numberA, operation1.numberB, operation1.GetResult());

    Factory factory2 = new SubFactory();

    Operation operation2 = factory2.CreateOperation();

    operation2.numberA = 10;

    operation2.numberB = 20;

    Console.WriteLine("{0}+{1}={2}", operation2.numberA, operation2.numberB, operation2.GetResult());

    Console.Read();

}