判断请求是否来自 AJAX

代码如下：

 public static bool IsAjaxRequest(this HttpRequest request)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }
            return (request["X-Requested-With"] == "XMLHttpRequest") || ((request.Headers != null) && (request.Headers["X-Requested-With"] == "XMLHttpRequest"));
        }