上传大文件问题

HttpApplication application1 = sender as HttpApplication;
        HttpWorkerRequest request1 = (HttpWorkerRequest)((IServiceProvider)HttpContext.Current).GetService(typeof(HttpWorkerRequest));
        try
        {
            if (application1.Context.Request.ContentType.IndexOf("multipart/form-data") <= -1)
            {
                return;
            }
            //Check The HasEntityBody
            if (!request1.HasEntityBody())
            {
                return;
            }            int num1 = 0;
            TimeSpan span1 = DateTime.Now.Subtract(this.beginTime);            string text1 = application1.Context.Request.ContentType.ToLower();            byte[] buffer1 = Encoding.ASCII.GetBytes(("\r\n--" + text1.Substring(text1.IndexOf("boundary=") + 9)).ToCharArray());
            int num2 = Convert.ToInt32(request1.GetKnownRequestHeader(11));
            Progress progress1 = new Progress();            application1.Context.Items.Add("FileList", new Hashtable());            byte[] buffer2 = request1.GetPreloadedEntityBody();
            num1 += buffer2.Length;            string text2 = this.AnalysePreloadedEntityBody(buffer2, "UploadGUID");
            if (text2 != string.Empty)
            {
                application1.Context.Items.Add("LionSky_UpLoadModule_UploadGUID", text2);
            }
            bool flag1 = true;
            if ((num2 > this.UpLoadFileLength()) && ((0 > span1.TotalHours) || (span1.TotalHours > 3)))
            {
                flag1 = false;
            }
请问这段代码中的this指的是什么？