设计模式（二）Abstract Factory

概述

在软件系统中，经常面临着“一系列相互依赖的对象”的创建工作；同时由于需求的变化，往往存在着更多系列对象的创建工作。如何应对这种变化？如何绕过常规的对象的创建方法（new），提供一种“封装机制”来避免客户程序和这种“多系列具体对象创建工作”的紧耦合？这就是我们要说的抽象工厂模式。

意图

提供一个创建一系列相关或相互依赖对象的接口，而无需指定它们具体的类。

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

namespace AbstractFactoryDemo
{
    class Program
    {
      
        static void Main(string[] args)
        {
            AbstractFactory factory = AbstractFactory.GetInstance();

            IBonus bonus= factory.CreateBonus();
            ITax tax = factory.CreateTax();

            Console.WriteLine(tax.Calculate().ToString());
            Console.WriteLine(bonus.Calculate().ToString());
            Console.Read();
        }
       
    }
}

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

namespace AbstractFactoryDemo
{
   public interface ITax
    {
        double Calculate();
    }
   public interface IBonus
    {
        double Calculate();
    }
}

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

namespace AbstractFactoryDemo
{

    public class ChineseBonus : IBonus
    {
        public double Calculate()
        {
            return Constant.Base_SALARY * 0.1;
        }
    }
    public class ChineseTax : AbstractFactoryDemo.ITax
    {
        public double Calculate()
        {
            return (Constant.Base_SALARY + (Constant.Base_SALARY * 0.1)) * 0.4;
        }
    }
}

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


namespace AbstractFactoryDemo
{
    public class AmericanBonus:IBonus
    {
        public double Calculate()
        {
            return Constant.Base_SALARY * 0.1;
        }
    }
    public class AmericanTax: ITax
    {
        public double Calculate()
        {
            return (Constant.Base_SALARY + (Constant.Base_SALARY * 0.1)) * 0.5;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;

namespace AbstractFactoryDemo
{
    //创建静态常量类   
    public  static class Constant
    {
        public static double Base_SALARY = 4000;
        public static string STR_FACTORYNAME = "AbstractFactoryDemo.ChineseFactory";
    }

   public abstract class  AbstractFactory
    {
        public static AbstractFactory GetInstance()
        {
            string factoryName = Constant.STR_FACTORYNAME;
            //利用反射机制实现字符串创建对象
            AbstractFactory instance;
            Type typeGetType = Type.GetType(factoryName);
            if (factoryName != "")
                instance = (AbstractFactory)Activator.CreateInstance(typeGetType);
                //instance = (AbstractFactory)Assembly.Load(factoryName).CreateInstance(factoryName);
            else
                instance = null;

            return instance;
        }

       public  abstract ITax CreateTax();


       public  abstract IBonus CreateBonus();
    }

   public class ChineseFactory : AbstractFactory
   {
       public override ITax CreateTax()
       {
           return new ChineseTax() ;
       }

       public override IBonus CreateBonus()
       {
           return new ChineseBonus();
       }
   }

   public class AmericanFactory : AbstractFactory 
   {
       public override ITax CreateTax()
       {
           return new AmericanTax();
       }

       public override IBonus CreateBonus()
       {
           return new AmericanBonus();
       }
   }
}

|--AbstractFactory   getInstance();   // 利用反射机制获取具体对象CreateTax();CreateBonus();

        |---chineseFactory      ITax CreateTax();IBonus CreateBonus();

        |---AmericanFactory    ITax  CreateTax();IBonus CreateBonus();

 |--ITax   

        ChineseTax:ITax;

        AmericanTax:ITax;

 |--IBonus

       chineseBonus:IBonus;

        AmericanBonus:IBonus;