简单工厂

简单工厂的意图在于：抽象出了公共部分，独立出每一个方法继承自父类，降低每一个方法之间的耦合度，并且防止了新增or修改方法类带来的代码错误，

前端只需要传入的运算规则即可得到结果

抽象实体

public class Operation
    {
        public double numberA { get; set; }
        public double numberB { get; set; }
        public virtual double GetResult() {
            double result = 0;
            return result;
        }
        
    }

独立的方法实现

public class OperationAdd:Operation
    {
        public override double GetResult()
        {
            double result=0d;
            result = numberA + numberB;
            return result;
        }
    }

    public class OperationSub : Operation
    {
        public override double GetResult()
        {
            double result = 0d;
            result = numberA - numberB;
            return result;
        }
    }

工厂构造器

public class OperationFactory
    {
        public static Operation createOperation(string operat) {
            Operation oper = null;
            switch (operat)
            {
                case "+":
                    oper = new OperationAdd();
                    break;
                case "-":
                    oper = new OperationSub();
                    break;

                default:

                    break;
            }
            return oper;
        }
    }

UI界面

static void Main(string[] args)
        {
            Operation oper = null;
            oper = OperationFactory.createOperation("+");
            oper.numberA = 2;
            oper.numberB = 10;
            double result=oper.GetResult();
            Console.WriteLine(result);
            Console.ReadKey();
        }