IHttpModule

ublic class modelHandler:IHttpModule
{
 public modelHandler()
 {
 }

    public void Dispose()
    {
        throw new Exception("The method or operation is not implemented.");
    }

    public void Init(HttpApplication context)
    {
        context.BeginRequest += new EventHandler(this.Application_BeginRequest);
        context.EndRequest += new EventHandler(this.Application_EndRequest);
    }
    public void Application_BeginRequest(Object sender, EventArgs e)
    {
        HttpApplication application = (HttpApplication)sender;

        HttpContext context = application.Context;
        HttpResponse response = application.Response;
        HttpRequest request = application.Request;

        response.Write("来自Application_BeginRequest");
    }

    public void Application_EndRequest(Object sender, EventArgs e)
    {
        HttpApplication application = (HttpApplication)sender;

        HttpContext context = application.Context;
        HttpResponse response = application.Response;
        HttpRequest request = application.Request;

        response.Write("来自Application_EndRequest");
    }
}

web.config

<httpModules>
      <add type="modelHandler" name="modeltest"/>
    </httpModules>