对于 Web API，您应该使用 System.Web.Http.dll 中的 System.Web.Http.AuthorizeAttribute 而不是 System.Web.Mvc.AuthorizeAttribute.

You should use System.Web.Http.AuthorizeAttribute from System.Web.Http.dll for Web API instead of System.Web.Mvc.AuthorizeAttribute.

也就是说，因为 namespace System.Web.Http.AuthorizeAttribute 派生自 AuthorizationFilterAttribute.过滤器由 Web API 自动处理.在我自己的实现中，我直接从 AuthorizationFilterAttribute 派生而来，用于处理基本的 HTTP 身份验证.

That is, because namespace System.Web.Http.AuthorizeAttribute is derived from AuthorizationFilterAttribute. The filters are handled automatically by the Web API. In my own implementation I derived directly from AuthorizationFilterAttribute for handling of the basic HTTP authentication.