如何使用Reflection创建通用对象(How do create a Generic Object using Reflection)

 首先让我说，我想要做的是获取泛型类中的属性值，该类可以由继承自它的类覆盖。 可以将它在基类中视为默认值，类的继承者可以覆盖它以设置自己的默认值。 
 
 我尝试使用System.Reflection.FieldInfo.GetValue直接在类型上使用反射，但这对于具有泛型类型的类不起作用。 所以我认为我需要实例化类才能看到值是什么。 
 
 我通过读取bin中的Dll并使用Reflection查找从我的界面继承的类型来检索“类型”。 
 
 我使用的是.NET 4.5 
 
 这里的文档似乎正好解释了我需要做什么http://msdn.microsoft.com/en-us/library/b8ytshk6.aspx 
 
 在这个文档中我唯一的区别是我们如何得到我们的类型，我在bin中查找类型，他们只是调用typeof（），因为类型太复杂了，看起来这可能是一个可能不匹配但我看不到缺少什么（如果有的话） 
 
foreach (var item in types)
{
    var ts = item.GetField("DefaultTimeToExpire");
    Type[] typeArguments = item.GetGenericArguments();
    if (ts != null)
    {
        var t = item.MakeGenericType(typeArguments);
        var obj = Activator.CreateInstance(t);
        var timespan = obj.DefaultTimeToExpire;
        subscriberInfos.Add(new Tuple<string, Type, TimeSpan>(item.Name, item, timespan));
    }
}
 
 我正在调用GetField来查找具有字段“DefaultTimeToExpire”的项目到目前为止，这部分可以很好地找到我需要的类型。 接下来，我调用GetGenericArguments，它返回Arguments类型的预期数组。 然后我调用MakeGenericType，最后创建实例，给我错误信息 
 
 “无法创建BusinessLogic.TestSubscriberXXX`1 [Message]的实例，因为Type.ContainsGenericParameters为true。” 
 
 这看起来就像我应该做的那样。 谢谢 

First let me say, that what I want to do is get the value of a property in a generic class that may be overriden by class that inherits from it. Think of it in the base class as a default value, that the inheritor of the class can override to set their own Default value.
 
I have tried to use reflection directly on the type, using the System.Reflection.FieldInfo.GetValue but this does not work for classes with generic types. So I think that I need to instantiate the class to be able to see what the value is.
 
The "types" I have I retrieved by reading the Dlls in the bin and using Reflection to find the types that inherit from my interface.
 
I am using .NET 4.5 
 
here is documentation that seems like it explains exactly what I need to do http://msdn.microsoft.com/en-us/library/b8ytshk6.aspx
 
In this documentation the only difference I can see is how we got our types, I looked in the bin for types and they simply called typeof(), Since types are so complex it seems this may be a likely mis-match but I cannot see what is missing(if anything)
 
foreach (var item in types)
{
    var ts = item.GetField("DefaultTimeToExpire");
    Type[] typeArguments = item.GetGenericArguments();
    if (ts != null)
    {
        var t = item.MakeGenericType(typeArguments);
        var obj = Activator.CreateInstance(t);
        var timespan = obj.DefaultTimeToExpire;
        subscriberInfos.Add(new Tuple<string, Type, TimeSpan>(item.Name, item, timespan));
    }
}
 
I am calling GetField to look for Items that have a field "DefaultTimeToExpire" so far this part works well to find the type I need. Next I call GetGenericArguments which returns an expected array of the type Arguments. then I call MakeGenericType and finally Create instance wich gives me the error message 
 
"Cannot create an instance of BusinessLogic.TestSubscriberXXX`1[Message] because Type.ContainsGenericParameters is true."
 
This looks like exactly what I am supposed to do. Thanks

原文：https://stackoverflow.com/questions/12168536