设计模式之—简单工厂模式<Simple Factory Pattern >

简单工厂模式结构图：

简单工厂模式以简单的加减乘除运算为例：

运算符类（Operation）：

namespace CalcTest.Simple_Factory_patterns
{
    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;
        }
    }
}

加法类（Add）：继承于运算符类（Operation）

 namespace CalcTest.Simple_Factory_patterns
 {
     class Add :Operation
     {
         public override double GetResult()
         {
             return NumberA + NumberB;
         }
     }
 }

减法类（Subtraction）：继承于运算符类（Operation）

 namespace CalcTest.Simple_Factory_patterns
 {
     class Subtraction : Operation
     {
         public override double GetResult()
         {
             return NumberA - NumberB;
         }
     }
 }

乘法类（Multiplacation）：继承于运算符类（Operation）

 namespace CalcTest.Simple_Factory_patterns
 {
     class Multiplication : Operation
     {
         public override double GetResult()
         {
             return NumberA * NumberB;
         }
     }
 }

除法类（Division）：继承于运算符类（Operation）

 namespace CalcTest.Simple_Factory_patterns
 {
     class Division : Operation
     {
         public override double GetResult()
         {
             if (NumberB == )
             {
                 throw new Exception("除数不能为0");
             }
             return NumberA / NumberB;
         }
     }
 }

运算符工厂类（OperationFactory）：实例合适的对象，通过多态返回父类的方式实现计算结果

 namespace CalcTest.Simple_Factory_patterns
 {
     class OperationFactory
     {
         public static Operation createOperation(string operate)
         {
             Operation oper = null;
             switch (operate)
             {
                 case "+":
                     oper = new Add();
                     break;
                 case "-":
                     oper = new Subtraction();
                     break;
                 case "*":
                     oper = new Multiplication();
                     break;
                 case "/":
                     oper = new Division();
                     break;
             }
             return oper;
         }
     }
 }

测试类（Main）：

 namespace CalcTest.Simple_Factory_patterns
 {
     class TestMain
     {
         public static void Main(string[] args)
         {
             Operation oper = null;
             //先输入操作符利用简单工厂模式创建类
             Console.Write("请输入操作符：(+、-、*、/)");
             string operate = Console.ReadLine();
             oper = OperationFactory.createOperation(operate);

             Console.Write("请输入数字A：");
             oper.NumberA = Convert.ToDouble(Console.ReadLine());

             Console.Write("请输入数字B：");
             oper.NumberB = Convert.ToDouble(Console.ReadLine());
             double result = oper.GetResult();
             Console.WriteLine("结果为：" + result);
             Console.ReadLine();
         }
     }
 }

简单工厂模式操作结束！