设计模式之工厂方法模式(FactoryMethod)

工厂方法模式(Factory Method)：定义一个用于创建对象的接口，让子类决定实例化哪一个类，工厂方法是一个类的实例化延迟到其子类。
工厂方法是类的创建模式，定义一个创建产品对象的工厂接口，将实际创建工作推迟到子类。

Factory1.cs:

using System;
using System.Collections.Generic;
using System.Text;

//工厂方法模式(Factory Method)：定义一个用于创建对象的接口，让子类决定实例化哪一个
//类，工厂方法是一个类的实例化延迟到其子类。
//工厂方法是类的创建模式，定义一个创建产品对象的工厂接口，将实际创建工作推迟到子类。
namespace FactoryMethod
{
    class Factory1
    {
    }
    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 result = 0;
            return result;
        }
    }

    class OperationAdd : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA + NumberB;
            return result;
        }
    }

    class OperationSub : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA - NumberB;
            return result;
        }
    }

    class OperationMul : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA * NumberB;
            return result;
        }
    }

    class OperationDiv : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            if (NumberB == 0)
                throw new Exception("除数不能为0");
            result = NumberA / NumberB;
            return result;
        }
    }
    //工厂接口
    interface IFactory
    {
        Operation CreateOperation();
    }
    //具体工厂接口
    class AddFactory : IFactory
    {
        public Operation CreateOperation()
        {
            return new OperationAdd();
        }
    }
    class SubFactory : IFactory
    {
        public Operation CreateOperation()
        {
            return new OperationSub();
        }
    }
    class MulFactory : IFactory
    {
        public Operation CreateOperation()
        {
            return new OperationMul();
        }
    }
    class DivFactory : IFactory
    {
        public Operation CreateOperation()
        {
            return new OperationDiv();
        }
    }
}

Program.cs:

using System;
using System.Collections.Generic;
using System.Text;

namespace FactoryMethod
{
    class Program
    {
        static void Main(string[] args)
        {
            IFactory operFactory = new AddFactory();
            Operation oper = operFactory.CreateOperation();
            oper.NumberA = 1;
            oper.NumberB = 2;
            double result = oper.GetResult();
            Console.WriteLine(result);
            Console.Read();
        }
    }
}

运行结果：

3