C++博客-Life is Good.-随笔分类-Design Pattern

namespace FactoryMethod
{
  public abstract class LightFactory
  {
    public abstract Light CreateLight();
  }

  public class BulbLightFactory : LightFactory
  {
    public override Light CreateLight()
    {
      return new BulbLight();
    }
  }

  public class TubeLightFactory : LightFactory
  {
      public override Light CreateLight()
      {
        return new TubeLight();
      }
  }
}

namespace FactoryMethod
{
  public abstract class Light
  {
    public abstract void TurnOn();
    public abstract void TurnOff();
  }

  public class BulbLight : Light
  {
    public override void TurnOn()
    {
      Console.WriteLine("Bulb Ligh is Turned on.\n");
    }
    public override void TurnOff()
    {
      Console.WriteLine("Bulb Ligh is Turned off.\n");
    }
  }

  public class TubeLight : Light
  {
    public override void TurnOn()
    {
      Console.WriteLine("Tube Ligh is Turned on.\n");
    }
    public override void TurnOff()
    {
      Console.WriteLine("Tube Ligh is Turned off.\n");
    }
  }
}

namespace FactoryMethod
{
  public class Client
  {

  public static void Main()
    {
      LightFactory BulbFactory = new BulbLightFactory();
      LightFactory TubeFactory = new TubeLightFactory();

      Light l1 = BulbFactory.CreateLight();
      Light l2 = TubeFactory.CreateLight();

      l1.TurnOn();
      l1.TurnOff();

      Console.WriteLine("===============\n");

      l2.TurnOn();
      l2.TurnOff();
    }
  }
}

名称	Factory Method
结构
意图	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。Factory Method 使一个类的实例化延迟到其子类。
适用性	当一个类不知道它所必须创建的对象的类的时候。当一个类希望由它的子类来指定它所创建的对象的时候。当类将创建对象的职责委托给多个帮助子类中的某一个，并且你希望将哪一个帮助子类是代理者这一信息局部化的时候。