asp.net计算每个页面的执行时间_C#

asp.net计算每个页面的执行时间，无需要修改页面的相关代码，这段代码会给所有的页面统一加上执行时间显示
来源：http://stackoverflow.com/questions/1826657/page-generation-time-asp-net-mvc

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 */ }
}