阻止拦截ASP.NET Web API响应的FormsAuthenticationModule

在ASP.NET Web API中避免这种拦截的方法是什么？

在ASP.NET MVC4中,通过明确结束连接来防止此拦截非常容易：

public class MyMvcAuthFilter:AuthorizeAttribute
{
    protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
    {
        if (filterContext.HttpContext.Request.IsAjaxRequest() && !filterContext.IsChildAction)
        {
            filterContext.Result = new HttpStatusCodeResult(401);
            filterContext.HttpContext.Response.StatusCode = 401;
            filterContext.HttpContext.Response.SuppressContent = true;
            filterContext.HttpContext.Response.End();
        }
        else
            base.HandleUnauthorizedRequest(filterContext);
    }
}

但是在ASP.NET Web API中我无法显式地结束连接,因此即使我使用此代码,FormsAuthenticationModule也会拦截响应并将重定向发送到登录页面：

public class MyWebApiAuth: AuthorizeAttribute
{
    protected override void HandleUnauthorizedRequest(System.Web.Http.Controllers.HttpActionContext actionContext)
    {
        if(actionContext.Request.Headers.Any(h=>h.Key.Equals("X-Requested-With",StringComparison.OrdinalIgnoreCase)))
        {
            var xhr = actionContext.Request.Headers.Single(h => h.Key.Equals("X-Requested-With",StringComparison.OrdinalIgnoreCase)).Value.First();

            if (xhr.Equals("XMLHttpRequest",StringComparison.OrdinalIgnoreCase))
            {
                // this does not work either
                //throw new HttpResponseException(HttpStatusCode.Unauthorized);

                actionContext.Response = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.Unauthorized);
                return;
            }
        }

        base.HandleUnauthorizedRequest(actionContext);
    }
}

在ASP.NET Web API中避免此行为的方法是什么？我一直在看,我找不到办法.

问候.

PS：我不敢相信这是2012年,这个问题仍然存在.