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
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>)));
}
其他回答
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!
通过使用tck的答案，也可以用以下LINQ查询完成:
bool isBar = foo.GetType().GetInterfaces().Any(x =>
x.IsGenericType &&
x.GetGenericTypeDefinition() == typeof(IBar<>));
var genericType = typeof(ITest<>);
Console.WriteLine(typeof(Test).GetInterfaces().Any(x => x.GetGenericTypeDefinition().Equals(genericType))); // prints: "True"
interface ITest<T> { };
class Test : ITest<string> { }
这对我很管用。
如果你想要一个支持泛型基类型和接口的扩展方法，我扩展了sduplooy的答案:
public static bool InheritsFrom(this Type t1, Type t2)
{
if (null == t1 || null == t2)
return false;
if (null != t1.BaseType &&
t1.BaseType.IsGenericType &&
t1.BaseType.GetGenericTypeDefinition() == t2)
{
return true;
}
if (InheritsFrom(t1.BaseType, t2))
return true;
return
(t2.IsAssignableFrom(t1) && t1 != t2)
||
t1.GetInterfaces().Any(x =>
x.IsGenericType &&
x.GetGenericTypeDefinition() == t2);
}
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>)));
}
