C#学习笔记-工厂模式

题目：计算器

解析：工厂方法（Factory Method)，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。

定义运算类：

 class Operation
     {
         private double _numberA = ;
         private double _numberB = ;

         public double NumberA
         {
             get
             {
                 return _numberA;
             }

             set
             {
                 _numberA = value;
             }
         }

         public double NumberB
         {
             get
             {
                 return _numberB;
             }

             set
             {
                 _numberB = value;
             }
         }

         public virtual double GetResult()
         {
             double result = ;
             return result;
         }
     }

继承于运算类的具体运算的实现：

 class OperationAdd : Operation
     {
         public override double GetResult()
         {
             double result = ;
             result = NumberA + NumberB;
             return result;
         }
     }

     class OperationSub : Operation
     {
         public override double GetResult()
         {
             double result = ;
             result = NumberA - NumberB;
             return result;
         }
     }

     class OperationMul : Operation
     {
         public override double GetResult()
         {
             double result = ;
             result = NumberA * NumberB;
             return result;
         }
     }

     class OperationDiv : Operation
     {
         public override double GetResult()
         {
             double result = ;
             if (NumberB == )
                 throw new Exception("除数不能为0");
             result = NumberA / NumberB;
             return result;
         }
     }

工厂方法，接口：

 interface IFactory
     {
         Operation CreateOperation();
     }

工厂方法，分别子类：

 class AddOperation : IFactory
     {
         public Operation CreateOperation()
         {
             return new OperationAdd();
         }
     }

     class SubOperation : IFactory
     {
         public Operation CreateOperation()
         {
             return new OperationSub();
         }
     }

     class MulOperation : IFactory
     {
         public Operation CreateOperation()
         {
             return new OperationMul();
         }
     }

     class DivOperation:IFactory
     {
         public Operation CreateOperation()
         {
             return new OperationDiv();
         }
     }

主函数：

 static void Main(string[] args)
         {
             //工厂模式自己内部确定了改实例化哪个类，所以要发生变动，只需要在最外面这个地方变动即可
             IFactory operFactory = new AddOperation();

             Operation oper = operFactory.CreateOperation();
             oper.NumberA = ;
             oper.NumberB = ;
             double result = oper.GetResult();

             Console.WriteLine(result);

             Console.Read();
         }

注：文中所有代码及知识点均来自于《大话设计模式》,本人属于边学边看边敲代码边总结的阶段。