c# - 通过反射获取继承类的所有单例

Question

我有以下场景:

class Cow : Animal
{
   public int animalID;
   private static Cow instance;
   public static Cow Instance
   {
      get 
      {  
          if (instance == null) instance = new Cow();
          return instance;     
      }
    }
   private Cow() { }
}

Cow是继承自 Animal 的普通单例.我需要的是:Dictionary<int, Animal>所有继承自 Animal 类型的单例，这样，a) 列表首先填充所有现有的单例[已经被实例化]，并且 b) 一个方法添加到我的字典项目还没有被实例化。

对于已实现的 Cow、Goat 和 Zebra 类，我想要这样的行为:

public class Cow : Animal { ... }
public class Goat : Animal { ... }
public class Zebra : Animal { ... }

public static class AnimalManagement
{
   static Dictionary<int, Animal> zoo = new Dictionary<int, Animal>();
   static void FillDictionary();
   static Animal GetAnimalID(int animalID);    
}

public Main()
{
   var a1 = Cow.Instance;
   var a2 = Goat.Instance;

   AnimalManagement.FillDictionary();
   // Now, zoo.Count() == 2

   // Suppose I seeking for Zebra, with animalID  == 5:
   Animal zebra = AnimalManagement.GetAnimalID(5);
   // Thus, zoo.Count() == 3 and zeebra singleton was 
   // instantiated and added to internal dic of AnimalManagement.
}

所以我想在运行时通过反射来填充字典。有可能吗我的 friend 们？

提前致谢!

Answer 1

本质上:

var types = myAssembly.GetTypes(t => typeof(Animal).IsAssignableFrom(t) && !t.IsAbstract);
var instances = types.Select(t => t.GetProperty("Instance", B.Static).GetValue(null, null));