简单工厂模式

开始看设计模式了,刚开始打算快速看完,然后再回过头来实现,但是走着发现这样不太好.

因为好多后边的模式应用到了前边的模式.前面的一知半解的话,导致后边的也知道一点.

就是什么也没有留下.

其次就是C#不太熟悉,需要实践一下.这样对看懂后来的模式会有很大的帮助.

下面说说简单工厂模式:

什么是简单工厂模式:

简单工厂模式的实质是由一个工厂类根据传入的参数，动态决定应该创建哪一个产品类（这些产品类继承自一个父类或接口）的实例.通俗的讲,也就是我这个公司能生产很多产品,但是具体在何种情况下生产何种产品是不知道的.必需由客户提供一个参数,也就是客户要我生产那个我就生产那个.生产的过程就是一个实例化类的过程.

简单工厂模式UML图

工厂代码:(C#),描述根据参数选择实例那种算法.

  1: public class OperatonFactory
  2:     {
  3:         public static Operation createOperate(String Operate)
  4:         {
  5:             Operation oper = null;
  6:             switch (Operate)
  7:             {
  8:                 case "+":
  9:                     oper = new OperatonAdd();
 10:                     break;
 11:                 case "-":
 12:                     oper = new OperationSub();
 13:                     break;
 14:                 case "*":
 15:                     oper = new OperationMul();
 16:                     break;
 17:                 case "/":
 18:                     oper = new OperationDiv();
 19:                     break;
 20:             }
 21:             return oper;
 22:         }
 23:     }

这样在客户端.就可以利用传过来的参数,实例化对象.

  1: Operation oper;
  2: Console.WriteLine("选择符号+-*/");
  3: oper = OperatonFactory.createOperate(Console .ReadLine ());//根据输入参数选择实例化对象

其中要实例化的类由一个抽象类和几个具体实现类组成.这样加强了代码的复用.减少了耦合.避免了添加功能时要给出原来功能的算法.体现了封装.

  1: public class Operation
  2:     {
  3:         private double _numberA = 0;
  4:         private double _numberB = 0;
  5: 
  6:         public double NumberA
  7:         {
  8:             get { return _numberA; }
  9:             set { _numberA = value; }
 10:         }
 11: 
 12:         public double NumberB
 13:         {
 14:             get { return _numberB; }
 15:             set { _numberB = value; }
 16: 
 17:         }
 18: 
 19:         public virtual double GetResult()
 20:         {
 21:             double result = 0;
 22:             return result;
 23: 
 24:         }
 25:     }
 26: 
 27:     class OperatonAdd : Operation
 28:     {
 29:         public override double GetResult()
 30:         {
 31:             double result = 0;
 32:             result = NumberA + NumberB;
 33:             return result;
 34:         }
 35:     }
 36: 
 37:     class OperationSub : Operation
 38:     {
 39:         public override double GetResult()
 40:         {
 41:             double result = 0;
 42:             result = NumberA - NumberB;
 43:             return result;
 44:         }
 45:     }
 46: 
 47:     class OperationMul : Operation
 48:     {
 49:         public override double GetResult()
 50:         {
 51:             double result = 0;
 52:             result = NumberA * NumberB;
 53:             return result;
 54:         }
 55:     }
 56: 
 57:     class OperationDiv : Operation
 58:     {
 59:         public override double GetResult()
 60:         {
 61:             double result = 0;
 62:             if (NumberB == 0)
 63:                 throw new Exception("除数不能为零");
 64: 
 65:             result = NumberA / NumberB;
 66:             return result;
 67: 
 68:         }
 69:     }