自定义AuthorizationFilterAttribute显示默认登录页面，而不是json消息

Question

我有一个客户身份验证过滤器属性来保护我的WebApi界面。似乎可行，但是显示了默认的MVC登录页面。我真的只想返回一个json作为正文。我该如何实现？

public class TokenAuthenticationAttribute : AuthorizationFilterAttribute
{
    public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
    {
        try
        {
            if (actionContext.Request.Headers.Authorization == null)
            {
                actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized, "No token specified");
            }
            else
            {
                string authenticationString = actionContext.Request.Headers.Authorization.Parameter;
                string token = Encoding.UTF8.GetString(Convert.FromBase64String(authenticationString));

                Device[] devices = DeviceManager.getInstance().getListOfDevices();
                if(devices.Where(a => a.token.Equals(token)).Count() == 0)
                {
                    actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized, "Invalid token");
                }
            }

            base.OnAuthorization(actionContext);
        }
        catch
        {
            actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized, "Invalid token");
        }
    }
}