文件流解析excel和txt

上传解析：

            HttpPostedFile file = HttpContext.Current.Request.Files[0];
            string fileType = Path.GetExtension(file.FileName);
            Stream s = file.InputStream;
            DataTable dt = new DataTable();
            try
            {
                if (fileType.ToLower() == ".txt")
                {
                    dt.Columns.Add("gameAccount");
                    StreamReader sr = new StreamReader(s, Encoding.Default);
                    string line;
                    while ((line = sr.ReadLine()) != null)
                    {
                        if (!string.IsNullOrWhiteSpace(line))
                        {
                            DataRow dr = dt.NewRow();
                            dr["gameAccount"] = line;
                            dt.Rows.Add(dr);
                        }
                    }
                }
                else
                {
                    dt = ImportExcel(s);
                }
            }

解析excel需要引用npoi：

        /// <summary>
        /// 读取Excel内容 
        /// </summary>
        /// <param name="inputStream"></param>
        /// <returns></returns>
        [NonAction]
        public DataTable ImportExcel(Stream inputStream)
        {
            try
            {
                DataTable dt = new DataTable();

                HSSFWorkbook hssfworkbook;

                hssfworkbook = new HSSFWorkbook(inputStream);

                HSSFSheet sheet = (HSSFSheet)hssfworkbook.GetSheetAt(0);
                System.Collections.IEnumerator rows = (System.Collections.IEnumerator)sheet.GetRowEnumerator();

                HSSFRow headerRow = (HSSFRow)sheet.GetRow(0);
                int cellCount = headerRow.LastCellNum;

                for (int j = 0; j < cellCount; j++)
                {
                    HSSFCell cell = (HSSFCell)headerRow.GetCell(j);
                    dt.Columns.Add(cell.ToString());
                }

                for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
                {
                    HSSFRow row = (HSSFRow)sheet.GetRow(i);
                    DataRow dataRow = dt.NewRow();
                    if (row == null) continue;
                    for (int j = row.FirstCellNum; j < cellCount; j++)
                    {
                        if (row.GetCell(j) != null)
                        {
                            dataRow[j] = row.GetCell(j).ToString();
                        }
                    }
                    dt.Rows.Add(dataRow);
                }
                return dt;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }