try
            {

                var workbook = new XLWorkbook();
                if (Workbook != null)
                {
                    workbook = Workbook;
                }
                if (this.ExportData != null || this.Workbook != null)
                {
                    context.HttpContext.Response.Clear();

                    // 編碼
                    context.HttpContext.Response.ContentEncoding = Encoding.UTF8;

                    // 設置網頁ContentType
                    context.HttpContext.Response.ContentType =
                        "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

                    // 導出名字
                    var browser = context.HttpContext.Request.Browser.Browser;
                    var exportFileName = browser.Equals("Firefox", StringComparison.OrdinalIgnoreCase)
                        ? this.FileName
                        : HttpUtility.UrlEncode(this.FileName, Encoding.UTF8);

                    context.HttpContext.Response.AddHeader(
                        "Content-Disposition",
                        string.Format("attachment;filename={0}", exportFileName));

                    // Add all DataTables in the DataSet as a worksheets
                    if (ExportData != null)
                        workbook.Worksheets.Add(this.ExportData, this.SheetName);

                    using (var memoryStream = new MemoryStream())
                    {
                        workbook.SaveAs(memoryStream);
                        memoryStream.WriteTo(context.HttpContext.Response.OutputStream);
                        memoryStream.Close();
                    }
                }
                workbook.Dispose();
            }
            catch
            {
                throw;
            }

asp.net文件流下載的代碼摘要