asp.net – 没有使用WebApi委托处理程序分配内部处理程序

我有一个WebApi在我的代码中抛出异常的问题：

public class WebApiAuthenticationHandler : DelegaTingHandler
    {
        private const String AuthToken = "AUTH-TOKEN";

        protected override Task<httpResponsemessage> SendAsync(
            httprequestmessage request,CancellationToken cancellationToken)
        {                  
            var requestAuthTokenList = GetrequestAuthTokens(request);
            if (ValidAuthorization(requestAuthTokenList))
            {
                // EXCEPTION is occuring here!....
                return base.SendAsync(request,cancellationToken);
            }

            /*
            ** This will make the whole API protected by the API token.
            ** To only protect parts of the API then mark controllers/methods
            ** with the Authorize attribute and always return this:
            **
            ** return base.SendAsync(request,cancellationToken);
            */
            return Task<httpResponsemessage>.Factory.StartNew(
                () =>
                {
                    var resp = new httpResponsemessage(httpStatusCode.Unauthorized)
                    {
                        Content = new StringContent("Authorization failed")
                    };

                    //var resp = new httpResponsemessage(httpStatusCode.Unauthorized);                                                                                   
                    //resp.Headers.Add(SuppressFormsAuthenticationRedirectModule.SuppressFormsHeaderName,"true");
                    return resp;
                });
        }

例外情况正在发生：

base.SendAsync(request,cancellationToken);

我不知道如何解决这个问题.我的路线表中有以下内容：

routes.MaphttpRoute("NoAuthrequiredApi","api/auth/",new { Controller = "Auth" });
    routes.MaphttpRoute("DefaultApi","api/{Controller}/{iD}",new { id = RouteParameter.optional },null,new WebApiAuthenticationHandler());

发生这种路由是DefaultApi路由.任何帮助非常感谢….

public class WebApiAuthenticationHandler : DelegaTingHandler
{
    public WebApiAuthenticationHandler(httpConfiguration httpConfiguration)
    {
        InnerHandler = new httpControllerDispatcher(httpConfiguration); 
    }

routes.MaphttpRoute("DefaultApi",WebApiAuthenticationHandler(GlobalConfiguration.Configuration));