Execl时间导入异常问题

        /// <summary>  
        /// 根据Excel列类型获取列的值  
        /// </summary>  
        /// <param name="cell">Excel列</param>  
        /// <returns></returns>  
        public static string GetCellValue(ICell cell)
        {
            if (cell == null) { return string.Empty; }
            switch (cell.CellType)
            {
                case CellType.Blank:
                    return string.Empty;
                case CellType.Boolean:
                    return cell.BooleanCellValue.ToString();
                case CellType.Error:
                    return cell.ErrorCellValue.ToString();
                case CellType.Numeric:
                    short format = cell.CellStyle.DataFormat;
                    if (format == 14 || format == 31 || format == 57 || format == 58)
                    {
                        //DateTime date = cell.DateCellValue;//这里报错，断点走进来不报错
　　　　　　　　　　　　　　
　　　　　　　　　　　　　　 DateTime date = DateTime.FromOADate(cell.NumericCellValue);//修改成这个
                        string re = date.ToString("yyy-MM-dd");
                        return re;
                    }
                    else
                    {
                        return cell.ToString();
                    }
                case CellType.Unknown:
                default:
                    //This is a trick to get the correct value of the cell. NumericCellValue will return a numeric value no matter the cell value is a date or a number  
                    return cell.ToString();
                case CellType.String:
                    return cell.StringCellValue;
                case CellType.Formula:
                    try
                    {
                        HSSFFormulaEvaluator e = new HSSFFormulaEvaluator(cell.Sheet.Workbook);
                        e.EvaluateInCell(cell);
                        return cell.ToString();
                    }
                    catch
                    {
                        return cell.NumericCellValue.ToString();
                    }
            }
        }

补充：Execl获取导入的数据

　　　　　　　　　　　//获取上传的Excel文件
　　　　　　　　　　　HttpPostedFileBase File = Request.Files["file"];

　　　　　　　　　　//判定Execl版本
                ISheet sheet = null; 
                var inp = File.InputStream;
                if (POIFSFileSystem.HasPOIFSHeader(inp))
                {
                    var hssfworkbook = new HSSFWorkbook(inp);
                    sheet = hssfworkbook.GetSheetAt(0);
                }
                if (POIXMLDocument.HasOOXMLHeader(inp))
                {
                    var hssfworkbook = new XSSFWorkbook(OPCPackage.Open(inp));
                    sheet = hssfworkbook.GetSheetAt(0);
                }

                DataTable table = new DataTable();
                IRow headerRow = sheet.GetRow(0);//第一行为标题行
                int cellCount = headerRow.LastCellNum;
                int rowCount = sheet.LastRowNum;
                for (int i = headerRow.FirstCellNum; i < cellCount; i++)
                {
                    DataColumn column = new DataColumn(ConvertNameToField(headerRow.GetCell(i).StringCellValue));
                    table.Columns.Add(column);
                }

                var check = CheckExcel(table);
                if (check != "")
                {
                    return Json(new { result, message = check }, JsonRequestBehavior.AllowGet);
                }
                for (int i = (sheet.FirstRowNum + 1); i <= rowCount; i++)
                {
                    IRow row = sheet.GetRow(i);
                    DataRow dataRow = table.NewRow();

                    if (row != null)
                    {
                        for (int j = row.FirstCellNum; j < cellCount; j++)
                        {
                            if (row.GetCell(j) != null)
                            {
                                dataRow[j] = GetCellValue(row.GetCell(j));
                            }
                        }
                    }
                    table.Rows.Add(dataRow);
                }