.Net 工厂模式(Factory Pattern)

目录

1. 定义
2. UML
3. 参与者
4. 示例

定义：

定义一个创建对象的接口,但是让子类来决定哪个类将被实例化。工厂方法让一个类实例化推迟到子类。

UML:

参与者：

产品(Project)角色:定义一个产品的接口。

具体产品(ConcreteProduct)角色： 实现这个产品角色接口的具体类。

工厂(Factory)角色：定义一个接口，用来创建产品。

具体工厂(ConcreteFactory)角色：实现工厂角色接口的具体类。

示例

using System;
 
namespace DoFactory.GangOfFour.Factory.Structural
{
  /// <summary>
  /// MainApp startup class for Structural
  /// Factory Method Design Pattern.
  /// </summary>
  class MainApp
  {
    /// <summary>
    /// Entry point into console application.
    /// </summary>
    static void Main()
    {
      // An array of creators
      Creator[] creators = new Creator[2];
 
      creators[0] = new ConcreteCreatorA();
      creators[1] = new ConcreteCreatorB();
 
      // Iterate over creators and create products
      foreach (Creator creator in creators)
      {
        Product product = creator.FactoryMethod();
        Console.WriteLine("Created {0}",
          product.GetType().Name);
      }
 
      // Wait for user
      Console.ReadKey();
    }
  }
 
  /// <summary>
  /// The 'Product' abstract class
  /// </summary>
  abstract class Product
  {
  }
 
  /// <summary>
  /// A 'ConcreteProduct' class
  /// </summary>
  class ConcreteProductA : Product
  {
  }
 
  /// <summary>
  /// A 'ConcreteProduct' class
  /// </summary>
  class ConcreteProductB : Product
  {
  }
 
  /// <summary>
  /// The 'Creator' abstract class
  /// </summary>
  abstract class Creator
  {
    public abstract Product FactoryMethod();
  }
 
  /// <summary>
  /// A 'ConcreteCreator' class
  /// </summary>
  class ConcreteCreatorA : Creator
  {
    public override Product FactoryMethod()
    {
      return new ConcreteProductA();
    }
  }
 
  /// <summary>
  /// A 'ConcreteCreator' class
  /// </summary>
  class ConcreteCreatorB : Creator
  {
    public override Product FactoryMethod()
    {
      return new ConcreteProductB();
    }
  }
}

Output：

Created ConcreteProductA
Created ConcreteProductB

实际运用：

  /// <summary>
    /// 产品接口
    /// </summary>
    public interface ICar
    {
        void OpenDoor();
    }

 /// <summary>
    /// 宝马车
    /// </summary>
    public class BaoMaCar : ICar
    {
        public void OpenDoor()
        {
            Console.WriteLine("打开宝马车门");
        }
    }

    /// <summary>
    /// 奥迪车
    /// </summary>
    public class AodiCar : ICar
    {
        public void OpenDoor()
        {
            Console.WriteLine("打开奥迪车门");
        }
    }
/// <summary>
    /// 工厂接口，用来创建哪个车
    /// </summary>
    public interface IFactory
    {
        ICar Create();
    }
/// <summary>
    /// 宝马工厂
    /// </summary>
    public class BaoMaFactory : IFactory
    {
        public ICar Create()
        {
            return new BaoMaCar();
        }
    }

    /// <summary>
    /// 奥迪工厂
    /// </summary>
    public class AoDiFactory : IFactory
    {
        public ICar Create()
        {
            return new AodiCar();
        }
    }
  static void Main(string[] args)
        {
            IFactory factory = new AoDiFactory();
            ICar car = factory.Create();
            car.OpenDoor();

            Console.Read();
        }

OutPut:

打开奥迪车门