public class TrackPageLoadPerformanceAttribute : ActionFilterAttribute{//这里使用log4net来打印出结果private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);//创建字典来记录开始时间，key是访问的线程Id.private readonly Dictionary<int, DateTime> _start = new Dictionary<int, DateTime>();//创建字典来记录当前访问的页面Url.private readonly Dictionary<int, string > _url = new Dictionary<int, string>();public override void OnActionExecuting(ActionExecutingContext filterContext){//过滤掉ChildAction, 因为ChildAction实际上不是一个单独的页面if(filterContext.IsChildAction) return;var currentThreadId = System.Threading.Thread.CurrentThread.ManagedThreadId;try{_start.Add(currentThreadId, DateTime.Now);_url.Add(currentThreadId, filterContext.HttpContext.Request.Url == null? string.Empty: filterContext.HttpContext.Request.Url.AbsoluteUri);}catch (Exception ex){Log.Error(ex.ToString());}}public override void OnResultExecuted(ResultExecutedContext filterContext){var currentThreadId = System.Threading.Thread.CurrentThread.ManagedThreadId;if (!_start.ContainsKey(currentThreadId)) return;try{//计算出当前页面访问耗时var costSeconds = (DateTime.Now - _start[currentThreadId]).TotalSeconds;if (costSeconds > 2)//如果耗时超过2秒，就是用log4net打印出，具体是哪个页面访问超过了2秒，具体使用了多长时间。{Log.Info(string.Format("Access the action more than 2 seconds. cost seconds {1}.  URL: {0}", _url[currentThreadId], costSeconds));}}catch (Exception ex){Log.Error(ex.ToString());}finally{_start.Remove(currentThreadId);_url.Remove(currentThreadId);}}}