浅浅一谈 设计模式

看软件设计资料，走到设计模式这里，一头雾水。遂翻书学习，这里简单记录一下，为以后复习用

1，简单工厂

  简单工厂  写一个计算 加减乘除的运算

 class Program
    {
        static void Main(string[] args)
        {
            SampleFactory factory = new SampleFactory();
            OperationClass operationclass = factory.CreateOpreation('/');
            //找到要操作的类了
            //对类进行初始化
            operationclass.FirstNum = 1;
            operationclass.SecondeNum = 3;

            //调用函数 进行计算
         double result=   operationclass.GetResult();
           
           Console.Write(result.ToString());
           Console.Read();
        }
    }

    /// <summary>
    /// 运算类
    /// </summary>
    class OperationClass
    {
        private double firstNum;

        public double FirstNum
        {
            get { return firstNum; }
            set { firstNum = value; }
        }
        private double secondeNum;

        public double SecondeNum
        {
            get { return secondeNum; }
            set { secondeNum = value; }
        }

        private double result;
        public virtual double GetResult()
        {
            result = 0;
            return result;
        }

    }


    class Add :OperationClass
    {
        public override double GetResult()
        {
            return FirstNum + SecondeNum;
        }
    }

    class Sub : OperationClass
    {
        public override double GetResult()
        {
            return FirstNum - SecondeNum;
        }
    }

    class Chu : OperationClass
    {
        public override double GetResult()
        {
            return FirstNum / SecondeNum;
        }
    }
    /// <summary>
    /// 简单工厂
    /// </summary>
    class SampleFactory
    {
        public OperationClass CreateOpreation(char c)
        {
            OperationClass operationclass;//运算类  基类
            switch (c)
            {
                case '+':
                    operationclass = new Add();
                    break;
                    case '-':
                    operationclass=new Sub();
                    break;
                    case '/':
                    operationclass = new Chu    ();
                    break;
                default:
                    operationclass =null;
                    break;
            }
            return operationclass;
        }
    }

在功能变动时

优点：客户端不用改代码

缺点：当需要增加新的运算类的时候，不仅需新加运算类，还要修改工厂类，违反了开闭原则。

2.工厂方法模式