如何确定asp.net请求生命周期的当前处理事件

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;

namespace Events
{
    public class Global : System.Web.HttpApplication
    {

        public Global()
        {
            BeginRequest += HandleEvent;
            EndRequest += HandleEvent;
            AcquireRequestState += HandleEvent;
            PostAcquireRequestState += HandleEvent;
        }

        private void HandleEvent(object sender, EventArgs e)
        {
            //httpContext类用于访问所有有关应用程序，所处理的请求以及正在构建的请求的信息，并且它的属性currentNotification定义了HttpApplication
事件的子集
            string eventName = "<Unknown>";
            switch (Context.CurrentNotification)
            {
                case RequestNotification.BeginRequest:
                case RequestNotification.EndRequest:
                    eventName = Context.CurrentNotification.ToString();
                    break;
                case RequestNotification.AuthenticateRequest:
                    break;
                case RequestNotification.AuthorizeRequest:
                    break;
                case RequestNotification.ResolveRequestCache:
                    break;
                case RequestNotification.MapRequestHandler:
                    break;
                    //当asp.net fromework需要与请求关联的状态时，将触发改事件
                case RequestNotification.AcquireRequestState:
                    if (Context.IsPostNotification)
                    {
                        eventName = "PostAcquireRequestState";
                    }
                    else
                    {
                        eventName = "AcquireRequestState";
                    }
                    break;
                case RequestNotification.PreExecuteRequestHandler:
                    break;
                case RequestNotification.ExecuteRequestHandler:
                    break;
                case RequestNotification.ReleaseRequestState:
                    break;
                case RequestNotification.UpdateRequestCache:
                    break;
                case RequestNotification.LogRequest:
                    break;
                case RequestNotification.SendResponse:
                    break;
                default:
                    break;
            }
            EventCollection.Add(EventSource.Application, eventName);
        }

        protected void Application_Start(object sender, EventArgs e)
        {
            EventCollection.Add(EventSource.Application, "Start");
            Application["message"] = "Aplication Events";
        }

        protected void Session_Start(object sender, EventArgs e)
        {

        }

        protected void Application_BeginRequest(object sender, EventArgs e)
        {
            //收到请求时触发的第一个事件
            EventCollection.Add(EventSource.Application, "BeginRequest");
            Response.Write(string.Format("request started at {0}", DateTime.Now.ToLongTimeString()));
        }

        protected void Application_EndRequest(object sender,EventArgs e)
        {
            EventCollection.Add(EventSource.Application, "EndRequest");
        }
        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {

        }

        

        protected void Application_Error(object sender, EventArgs e)
        {

        }

        protected void Session_End(object sender, EventArgs e)
        {

        }

        protected void Application_End(object sender, EventArgs e)
        {
            EventCollection.Add(EventSource.Application,"End");
        }
 
    }
}