假设有以下类型定义:

public interface IFoo<T> : IBar<T> {}
public class Foo<T> : IFoo<T> {}

我如何找出类型Foo是否实现了通用接口IBar<T>时,只有manged类型是可用的?


当前回答

我使用一个稍微简单的版本的@GenericProgrammers扩展方法:

public static bool Implements<TInterface>(this Type type) where TInterface : class {
    var interfaceType = typeof(TInterface);

    if (!interfaceType.IsInterface)
        throw new InvalidOperationException("Only interfaces can be implemented.");

    return (interfaceType.IsAssignableFrom(type));
}

用法:

    if (!featureType.Implements<IFeature>())
        throw new InvalidCastException();

其他回答

方法检查类型是否继承或实现泛型类型:

   public static bool IsTheGenericType(this Type candidateType, Type genericType)
    {
        return
            candidateType != null && genericType != null &&
            (candidateType.IsGenericType && candidateType.GetGenericTypeDefinition() == genericType ||
             candidateType.GetInterfaces().Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == genericType) ||
             candidateType.BaseType != null && candidateType.BaseType.IsTheGenericType(genericType));
    }

作为辅助方法扩展

public static bool Implements<I>(this Type type, I @interface) where I : class
{
    if(((@interface as Type)==null) || !(@interface as Type).IsInterface)
        throw new ArgumentException("Only interfaces can be 'implemented'.");

    return (@interface as Type).IsAssignableFrom(type);
}

使用示例:

var testObject = new Dictionary<int, object>();
result = testObject.GetType().Implements(typeof(IDictionary<int, object>)); // true!

试试下面的扩展。

public static bool Implements(this Type @this, Type @interface)
{
    if (@this == null || @interface == null) return false;
    return @interface.GenericTypeArguments.Length>0
        ? @interface.IsAssignableFrom(@this)
        : @this.GetInterfaces().Any(c => c.Name == @interface.Name);
}

为了测试它。创建

public interface IFoo { }
public interface IFoo<T> : IFoo { }
public interface IFoo<T, M> : IFoo<T> { }
public class Foo : IFoo { }
public class Foo<T> : IFoo { }
public class Foo<T, M> : IFoo<T> { }
public class FooInt : IFoo<int> { }
public class FooStringInt : IFoo<string, int> { }
public class Foo2 : Foo { }

以及测试方法

public void Test()
{
    Console.WriteLine(typeof(Foo).Implements(typeof(IFoo)));
    Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo)));
    Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<>)));
    Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<int>)));
    Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<string>)));
    Console.WriteLine(typeof(FooInt).Implements(typeof(IFoo<,>)));
    Console.WriteLine(typeof(FooStringInt).Implements(typeof(IFoo<,>)));
    Console.WriteLine(typeof(FooStringInt).Implements(typeof(IFoo<string,int>)));
    Console.WriteLine(typeof(Foo<int,string>).Implements(typeof(IFoo<string>)));
 }

以下内容应该没有任何问题:

bool implementsGeneric = (anObject.Implements("IBar`1") != null);

如果您想为IBar查询提供一个特定的泛型类型参数,您可以捕获AmbiguousMatchException。

您必须遍历继承树并找到树中每个类的所有接口,并将typeof(IBar<>)与调用Type的结果进行比较。GetGenericTypeDefinition如果接口是泛型的。当然,这一切都有点痛苦。

更多信息和代码请参见这个答案和这些答案。