asp.net计算每个页面执行时间的方法

public class PerformanceMonitorModule : IHttpModule
{
 public void Init(HttpApplication context)
 {
 context.PreRequestHandlerExecute += delegate(object sender,EventArgs e)
 {
 //Set Page Timer Star
 HttpContext requestContext = ((HttpApplication)sender).Context;
 Stopwatch timer = new Stopwatch();
 requestContext.Items["Timer"] = timer;
 timer.Start();
 };
 context.PostRequestHandlerExecute += delegate(object sender, EventArgs e)
 {
 HttpContext httpContext = ((HttpApplication)sender).Context;
 HttpResponse response = httpContext.Response;
 Stopwatch timer = (Stopwatch)httpContext.Items["Timer"];
 timer.Stop();
 // Don't interfere with non-HTML responses
 if (response.ContentType == "text/html")
 {
 double seconds = (double)timer.ElapsedTicks / Stopwatch.Frequency;
 string result_time = string.Format("{0:F4} sec ", seconds);
 RenderQueriesToResponse(response,result_time);
 }
 };
 }
 void RenderQueriesToResponse(HttpResponse response, string result_time)
 {
 response.Write("<div style=\"margin: 5px; background-color: #FFFF00\"");
 response.Write(string.Format("<b>Page Generated in "+ result_time));
 response.Write("</div>");
 }
 public void Dispose() { /* Not needed */ }
}