Castle IOC 實踐：TypedFactory Facility（一）使用篇

動機：解決 Factory Method 模式類爆炸

傳統 Factory Method 每個具體產品需對應一個工廠類，產品增多導致工廠管理困難。TypedFactory Facility 讓我們僅定義工廠介面，容器自動實現。資訊：

快速入門五步驟

1. 產品介面

public interface IProduct { void Display(); }

2. 多個具體產品

public class ConcreteProductA : IProduct { public void Display() => Console.WriteLine("ConcreteProductA"); }
public class ConcreteProductB : IProduct { public void Display() => Console.WriteLine("ConcreteProductB"); }
public class ConcreteProductC : IProduct { public void Display() => Console.WriteLine("ConcreteProductC"); }

3. 工廠介面（含建立與釋放方法）

public interface IFactory
{
    IProduct Create(string id);
    void Release(IProduct handler);
}

4. 配置檔

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <facilities>
    <facility id="typedfactory">
      <factories>
        <factory id="factory" interface="TypedFactoryFacilityDemo.IFactory, TypedFactoryFacilityDemo"
          creation="Create" destruction="Release" />
      </factories>
    </facility>
  </facilities>
</configuration>

5. 使用

public class App
{
    public static void Main()
    {
        IWindsorContainer container = new WindsorContainer(new XmlInterpreter("../../MyConfig.xml"));
        container.AddFacility("typedfactory", new TypedFactoryFacility());
        container.AddComponent("proda", typeof(IProduct), typeof(ConcreteProductA));
        container.AddComponent("prodb", typeof(IProduct), typeof(ConcreteProductB));
        container.AddComponent("prodc", typeof(IProduct), typeof(ConcreteProductC));
        IFactory factory = (IFactory)container["factory"]; // Key 為 factory 元素的 id
        IProduct pa = factory.Create("proda"); pa.Display();
        IProduct pb = factory.Create("prodb"); pb.Display();
        IProduct pc = factory.Create("prodc"); pc.Display();
        Console.ReadLine();
    }
}

全程零工廠實現類，新增產品只需註冊新組件。注意：解析工廠時的 Key 是配置中 <factory id="..."> 的 id，非 Facility id。下篇將解析原理。