ASP.NET 不經儲存直接讀取上傳檔案的內容

if (FileUpload1.PostedFile.InputStream.Length < 1)            {                return;            }            string fileName = FileUpload1.FileName;//檔案名稱            string filePath = FileUpload1.PostedFile.FileName;//檔案路徑            if (fileName.ToLower().IndexOf(".csv") == -1)            {                return;            }            int fileLen = FileUpload1.PostedFile.ContentLength;//檔案大小            byte[] input = new byte[fileLen];            System.IO.Stream fileUploadStream = FileUpload1.PostedFile.InputStream;            fileUploadStream.Read(input, 0, fileLen);            fileUploadStream.Position = 0;            System.IO.StreamReader sr = new System.IO.StreamReader(fileUploadStream, System.Text.Encoding.Default);            string strLine;            while ((strLine = sr.ReadLine()) != null)            {                strLine = strLine.Replace("\"", "");                string[] strBlock = strLine.Split(',');                //do something...            }            sr.Close();            fileUploadStream.Close();            sr = null;            fileUploadStream = null;