抽象工厂模式

提供用于创建相关或从属对象族的接口，而无需指定其具体类。

在这个例子中演示了使用不同工厂为计算机游戏创建不同的动物世界。虽然大陆工厂创造的动物不同，但动物之间的相互作用保持不变。

using System;
 
namespace GangOfFour.AbstractFactory
{
  /// <summary>
  /// MainApp startup class for Real-World
  /// Abstract Factory Design Pattern.
  /// </summary>
  class MainApp
  {
    /// <summary>
    /// Entry point into console application.
    /// </summary>
    public static void Main()
    {
      // Create and run the African animal world
      ContinentFactory africa = new AfricaFactory();
      AnimalWorld world = new AnimalWorld(africa);
      world.RunFoodChain();
 
      // Create and run the American animal world
      ContinentFactory america = new AmericaFactory();
      world = new AnimalWorld(america);
      world.RunFoodChain();
 
      // Wait for user input
      Console.ReadKey();
    }
  }
 
 
  /// <summary>
  /// The 'AbstractFactory' abstract class
  /// </summary>
  abstract class ContinentFactory
  {
    public abstract Herbivore CreateHerbivore();
    public abstract Carnivore CreateCarnivore();
  }
 
  /// <summary>
  /// The 'ConcreteFactory1' class
  /// </summary>
  class AfricaFactory : ContinentFactory
  {
    public override Herbivore CreateHerbivore()
    {
      return new Wildebeest();
    }
    public override Carnivore CreateCarnivore()
    {
      return new Lion();
    }
  }
 
  /// <summary>
  /// The 'ConcreteFactory2' class
  /// </summary>
  class AmericaFactory : ContinentFactory
  {
    public override Herbivore CreateHerbivore()
    {
      return new Bison();
    }
    public override Carnivore CreateCarnivore()
    {
      return new Wolf();
    }
  }
 
  /// <summary>
  /// The 'AbstractProductA' abstract class
  /// </summary>
  abstract class Herbivore
  {
  }
 
  /// <summary>
  /// The 'AbstractProductB' abstract class
  /// </summary>
  abstract class Carnivore
  {
    public abstract void Eat(Herbivore h);
  }
 
  /// <summary>
  /// The 'ProductA1' class
  /// </summary>
  class Wildebeest : Herbivore
  {
  }
 
  /// <summary>
  /// The 'ProductB1' class
  /// </summary>
  class Lion : Carnivore
  {
    public override void Eat(Herbivore h)
    {
      // Eat Wildebeest
      Console.WriteLine(this.GetType().Name +
        " eats " + h.GetType().Name);
    }
  }
 
  /// <summary>
  /// The 'ProductA2' class
  /// </summary>
  class Bison : Herbivore
  {
  }
 
  /// <summary>
  /// The 'ProductB2' class
  /// </summary>
  class Wolf : Carnivore
  {
    public override void Eat(Herbivore h)
    {
      // Eat Bison
      Console.WriteLine(this.GetType().Name +
        " eats " + h.GetType().Name);
    }
  }
 
  /// <summary>
  /// The 'Client' class 
  /// </summary>
  class AnimalWorld
  {
    private Herbivore _herbivore;
    private Carnivore _carnivore;
 
    // Constructor
    public AnimalWorld(ContinentFactory factory)
    {
      _carnivore = factory.CreateCarnivore();
      _herbivore = factory.CreateHerbivore();
    }
 
    public void RunFoodChain()
    {
      _carnivore.Eat(_herbivore);
    }
  }
}

输出：

狮子吃牛羚

狼吃野牛