从提供的类型返回泛型接口实现的类型

Question

给定一个实现接口的类:

public interface DomainEventSubscriber<T>
{
    void HandleEvent(T domainEvent);
}
public class TestEventHandler : DomainEventSubscriber<TestEvent1>, DomainEventSubscriber<OtherTestEvent1>
{
    public void HandleEvent(TestEvent1 domainEvent)
    {
    }
    public void HandleEvent(OtherTestEvent1 domainEvent)
    {
        throw new NotImplementedException();
    }
}

我想返回已实现的类型，即

static Type[] FindTypesForDomainEventSubscriberOfT(Type type)
{
     // given a TestEventHandler type, I should return a collection of { TestEvent1, OtherTestEvent1 }
}

这怎么能做到呢?

Answer 1

听起来你想要这样做:

static Type[] FindTypesForDomainEventSubscriberOfT(Type type)
{
    return type.GetInterfaces()
      .Where(x => x.IsGenericType &&
                  x.GetGenericTypeDefinition() == typeof(DomainEventSubscriber<>))
      .Select(x => x.GetGenericArguments()[0])
      .ToArray(); 
}

注意，这可能最终返回类型参数。例如，如果您有:

public class Foo<T> : DomainEventSubscriber<T>

则返回T，即Foo<T>的类型参数。如果你不想这样，你可以插入:

.Where(x => !x.IsGenericParameter)

ToArray呼叫前。

(我还建议您将接口重命名为具有I前缀，遵循。net命名约定。)

Answer 2

我猜你正在寻找的类型。GetGenericTypeDefinition Method

private static void DisplayTypeInfo(Type t)
{
    Console.WriteLine("rn{0}", t);
    Console.WriteLine("tIs this a generic type definition? {0}", 
        t.IsGenericTypeDefinition);
    Console.WriteLine("tIs it a generic type? {0}", 
        t.IsGenericType);
    Type[] typeArguments = t.GetGenericArguments();
    Console.WriteLine("tList type arguments ({0}):", typeArguments.Length);
    foreach (Type tParam in typeArguments)
    {
        Console.WriteLine("tt{0}", tParam);
    }
}