设计模式——简单工厂模式

简单工厂模式

1. 通过封装、继承、多态把程序的耦合度降低。用设计模式使得程序更加的灵活，容易修改，并且易于复用。
2. 让业务逻辑和界面逻辑分开，让它们耦合度降低，这样才容易维护和扩展。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

//要求输入两个数和运算符号，得到结果

namespace Calculator
{
    class Program
    {
        static void Main(string[] args)
        {
            
            Console.WriteLine("请输入一个数字");
            string strNum1 = Console.ReadLine();
            Console.WriteLine("请在输入一个数字");
            string strNum2 = Console.ReadLine();
            Console.WriteLine("请输入一个运算符");
            string strOp = Console.ReadLine();

            Operation oper = OperationFactory.CreateOperation(strOp);

            double num1 = double.Parse(strNum1);
            double num2 = double.Parse(strNum2);
            double result = oper.GetResult(num1, num2);

            Console.WriteLine($"{num1}{strOp}{num2}={result}");

        }
    }

    public class Operation
    {
        private double _numberA = 0;
        private double _numberB = 0;
        public double NumberA
        {
            get
            {
                return _numberA;
            }
            set
            {
                _numberA = value;
            }
        }
        public double NumberB
        {
            get
            {
                return _numberB;
            }
            set
            {
                _numberB = value;
            }
        }
        public virtual double GetResult(double num1,double num2)
        {
            return 0;
        }
    }

    class CalculateAdd : Operation
    {
        public override double GetResult(double num1, double num2)
        {
            return num1 + num2;
        }
    }
    class CalculateSub : Operation
    {
        public override double GetResult(double num1, double num2)
        {
            return num1 - num2;
        }
    }
    class CalculateMulti : Operation
    {
        public override double GetResult(double num1, double num2)
        {
            return num1 * num2;
        }
    }
    class CalculateDiv : Operation
    {
        public override double GetResult(double num1, double num2)
        {
            try
            {
                return num1 / num2;
            }
            catch (Exception ex)
            {
                throw ex;
            }       
        }
    }

    public class OperationFactory
    {
        static Operation oper = null;
        public static Operation CreateOperation(string op)
        {
            switch (op)
            {
                case "+":
                    oper = new CalculateAdd();
                    break;
                case "-":
                    oper = new CalculateSub();
                    break;
                case "*":
                    oper = new CalculateMulti();
                    break;
                case "/":
                    oper = new CalculateDiv();
                    break;
                default:
                    break;
            }
            return oper;
        }
    }

}