九.工厂方法模式

工厂方法模式：

       定义一个用于创建对象的接口，让子类决定实例化哪一个类

 

       把选择放到了客户端。

 

       与简单工厂的区别：克服简单工厂违背开放——封闭原则的缺点

              简单工厂的最大优点在工厂中包含必要的逻辑判断，根据客户端的传入条件动态选择实例化的类，对客户端来说去除了与具体产品的依赖。

 

实体和具体方法：

   class Operation

    {

       string num1 = string.Empty;

       string num2 = string.Empty;

 

       public string Num1

       {

           get { return num1; }

           set { num1 = value; }

       }

 

       public string Num2

       {

           get { return num2; }

           set { num2 = value; }

       }

 

       public virtual  string GetResult()

       {

           string result=string.Empty;

           return GetResult();

       }

    }

   class AddOperation : Operation

    {

       public override string GetResult()

       {

           string result;

           result = (Convert.ToDouble(Num1) + Convert.ToDouble(Num2)).ToString();

           return result;

       }

    }

   class SubOperation : Operation

    {

       public override string GetResult()

       {

           string result;

           result = (Convert.ToDouble(Num1) -Convert.ToDouble(Num2)).ToString();

           return result;

       }

}

 

工厂方法：

           interface IFactory

    {

       Operation CreateOperation();

    }

   class AddFactory : IFactory

    {

       public Operation CreateOperation()

       {

           return new AddOperation();

       }

    }

   class SubFactory : IFactory

    {

       public Operation CreateOperation()

       {

           return new SubOperation();

       }

}

调用工厂方法：

                   IFactoryoperFactory = new AddFactory();

           Operation oper = operFactory.CreateOperation();

           oper.Num1 = "2";

           oper.Num2 = "1";

           Console.WriteLine(oper.GetResult());

           Console.ReadKey();