简单工厂模式实例

运算类

public class operation
    {
        private double a = 0;
        private double b = 0;

        public double A
        {
            get { return a; }
            set { a = value; }
        }
        public double B
        {
            get { return b; }
            set { b = value; }
        }
        public virtual double GetResult()
        {
            double rst = 0;
            return rst;
        }
    }

加减乘除类

public class Jia : operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = A + B;
            return result;
        }
    }
    public class Jian : operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = A - B;
            return result;
        }
    }
    public class Cheng : operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = A * B;
            return result;
        }
    }
    public class Chu : operation
    {
        public override double GetResult()
        {
            double result = 0;
            if(B==0)
                throw new Exception("除数不能为0");
            result = A / B;
            return result;
        }
    }

工厂类

public class OperationFactory
    {
        public static operation CreateOperation(string operation)
        {
            operation result = null;
            switch (operation)
            {
                case "+": result = new Jia(); break;
                case "-": result = new Jian(); break;
                case "*": result = new Cheng(); break;
                case "/": result = new Chu(); break;
                default:
                    break;
            }
            return result;
        }
    }

控制台请求

            Console.Write("请输入第一个数");
            double a =Convert.ToDouble(Console.ReadLine());
            Console.Write("请输入第二个数");
            double b =Convert.ToDouble(Console.ReadLine());
            Console.Write("请输入运算符");
            string opr = Console.ReadLine();
            operation opr2 = OperationFactory.CreateOperation(opr);
            opr2.A = a;
            opr2.B = b;
            double result = opr2.GetResult();
            Console.WriteLine(result);
            Console.ReadLine();