简单工厂模式（设计模式入门）

1     public abstract class Operation
2     {
3         public double NumA { set; get; }
4         public double NumB { set; get; }
5         public virtual double GetResult()
6         {
7             return 0;
8         }
9     }

 1     public class OperationAdd : Operation
 2     {
 3         public override double GetResult()
 4         {
 5             double res = 0;
 6             res = base.NumA + base.NumB;
 7             return res;
 8         }
 9     }
10 
11     public class OperationSub : Operation
12     {
13         public override double GetResult()
14         {
15             double res = 0;
16             res = base.NumA - base.NumB;
17             return res;
18         }
19     }

 1     public class OperationFactory
 2     {
 3         public Operation CreateOperation(string op)
 4         {
 5             Operation res = null;
 6             switch (op)
 7             {
 8                 case "+":
 9                     res = new OperationAdd();
10                     break;
11                 case "-":
12                     res = new OperationSub();
13                     break;
14             }
15             return res;
16         }
17     }

 1     /// <summary>
 2     /// 简单工厂模式 - 将实例的选择放在了工厂类中
 3     /// </summary>
 4     public class DoSimpleFactory : DesignPattern
 5     {
 6         public override void ExeFun()
 7         {
 8             Console.WriteLine("请输入运算符:+、-、*、/");
 9             Operation ot = new OperationFactory().CreateOperation(Console.ReadLine());
10             ot.NumA = 2;
11             ot.NumB = 4;
12             double res = ot.GetResult();
13             Console.Write(string.Format("计算结果为:{0}", res));
14         }
15     }