抽象类中定义静态方法

       一直认为抽象类不能实例化，所以就没有想过用直接调用方法，而是实例化它的子类，用子类调用方法，
 没想到啊，在抽象类中定义static方法不就可以了吗，static方法属于类，不需要实例化。

using System;
using System.Reflection;

namespace AbstractFactory
{
 /// <summary>
 /// Factory类
 /// </summary>
 public abstract class AbstractFactory
 {
 
  public static AbstractFactory GetInstance()
  {
   string factoryName = Constant.STR_FACTORYNAME.ToString();

   AbstractFactory instance;

   if(factoryName != "")

                //AbstractFactory表示程序集的名称 ；factoryName表示要加载的类
                instance = (AbstractFactory)Assembly.Load("AbstractFactory").CreateInstance(factoryName);
   else
    instance = null;

   return instance;
  }

  public abstract Tax CreateTax();

  public abstract Bonus CreateBonus();
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 客户端程序调用
 /// </summary>
 public class Calculator
 {
  public static void Main(string[] args)
  {
            //GetInstance不是static方法
            //AbstractFactory abstractFactory = new ChineseFactory().GetInstance();
            //double bonusValue = abstractFactory.CreateBonus().Calculate();
            //double taxValue = abstractFactory.CreateTax().Calculate();

            //GetInstance是static方法
            double bonusValue = AbstractFactory.GetInstance().CreateBonus().Calculate();
            double taxValue = AbstractFactory.GetInstance().CreateTax().Calculate();
            double salary = 4000 + bonusValue - taxValue;
            Console.WriteLine("Salary is：" + salary);
            Console.ReadLine();

         
  }
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// ChineseFactory类
 /// </summary>
 public class ChineseFactory:AbstractFactory
 {
  public override Tax CreateTax()
  {
   return new ChineseTax();
  }

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

using System;

namespace AbstractFactory
{
 /// <summary>
 /// AmericanFactory类
 /// </summary>
 public class AmericanFactory:AbstractFactory
 {
  public override Tax CreateTax()
  {
   return new AmericanTax();
  }

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

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 计算中国个人奖金
 /// </summary>
 public class ChineseBonus:Bonus
 {
  public override double Calculate()
  {
   return Constant.BASE_SALARY * 0.1;
  }
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 计算美国奖金
 /// </summary>
 public class AmericanBonus:Bonus
 {
  public override double Calculate()
  {
   return Constant.BASE_SALARY * 0.1;
  }
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 计算美国个人所得税
 /// </summary>
 public class AmericanTax:Tax
 {
  public override double Calculate()
  {
   return (Constant.BASE_SALARY + (Constant.BASE_SALARY * 0.1)) * 0.4;
  }
 }
}

using System;

namespace AbstractFactory
{ 
 /// <summary>
 /// 计算中国个人所得税
 /// </summary>
 public class ChineseTax:Tax
 {
  public override double Calculate()
  {
   return (Constant.BASE_SALARY + (Constant.BASE_SALARY * 0.1)) * 0.4;
  }
 }
}

using System;
using System.Configuration;

namespace AbstractFactory
{
 /// <summary>
 /// 公用的常量
 /// </summary>
 public class Constant
 {
  public static double BASE_SALARY = 4000;

  public static string STR_FACTORYNAME = ConfigurationSettings.AppSettings["factoryName"];
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 个人所得税抽象类
 /// </summary>
 public abstract class Tax
 {
  public abstract double Calculate();
 }
}

using System;

namespace AbstractFactory
{
 /// <summary>
 /// 奖金抽象类
 /// </summary>
 public abstract class Bonus
 {
  public abstract double Calculate();
 }
}

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <appSettings>
  <add key="factoryName" value="AbstractFactory.ChineseFactory"></add>
 </appSettings>
 
</configuration>