使用反射来获得DLL一定基础类型的所有类 [英] Using reflection to get all classes of certain base type in dll

问题描述

我有一个包含了许多，所有从CommandBase类继承的类的DLL。我试图让所有使用C＃反射这些类（CommandA，CommandB，CommandC等）的情况下，这样我可以调用每一个特定的方法。以下是我迄今为止：

I have a dll that contains a number of classes that all inherit from a CommandBase class. I'm trying to get instances of all of these classes (CommandA, CommandB, CommandC, etc...) using reflection in C# so that I can call a specific method on each one. Here is what I have so far:

//get assemblies in directory.
string folder = Path.Combine(HttpContext.Current.Server.MapPath("~/"), "bin");
var files = Directory.GetFiles(folder, "*.dll");
//load each assembly.
foreach (string file in files)
{
  var assembly = Assembly.LoadFile(file);
  if (assembly.FullName == "MyCommandProject")
  {
    foreach (var type in assembly.GetTypes())
    {
      if (!type.IsClass || type.IsNotPublic) continue;
      if(type is CommandBase)
      {
        var command = Activator.CreateInstance(type) as CommandBase;
      }
    }
  }
}

我M有2个问题。第一问题是该行如果（类型为CommandBase），给出了以下警告：

I'm having 2 issues. The 1st issue is that the line "if(type is CommandBase") gives the following warning:

给定的表达式是从来没有提供的类型CommandBase的<。 / STRONG>

The given expression is never of the provided type CommandBase.

第二问题是，我无法弄清楚如何获得的实际对象（CommandA，CommandB等）的一个实例，只将其转换为CommandBase是不够的。

The 2nd issue is that I can't figure out how to get an instance of the actual object (CommandA, CommandB, etc...), just converting it to CommandBase isn't enough.

推荐答案

这是我使用基于接口的加载了该方法。

This is the method I use to load up based on an interface.

private static List<T> GetInstances<T>()
{
        return (from t in Assembly.GetExecutingAssembly().GetTypes()
                where t.GetInterfaces().Contains(typeof (T)) && t.GetConstructor(Type.EmptyTypes) != null
                select (T) Activator.CreateInstance(t)).ToList();
}

和下面是拉回到基于基类相同的功能。

And here's the same function that pulls back based on base class.

private static IList<T> GetInstances<T>()
{
        return (from t in Assembly.GetExecutingAssembly().GetTypes()
                       where t.BaseType == (typeof(T)) && t.GetConstructor(Type.EmptyTypes) != null
                       select (T)Activator.CreateInstance(t)).ToList();
}

当然，这将需要在参考你略作修改，以点重新载入。

Of course it would need to be modified slightly to point at the reference you're loading.

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