asp.net NPOI导出xlsx格式文件，打开文件报“Excel 已完成文件级验证和修复。此工作簿的某些部分可能已被修复或丢弃”

/// <summary>
///     将datatable数据写入excel并下载
/// </summary>
/// <param name="dt">datatable </param>
/// <param name="excelName">文件名</param>
/// <param name="templatePath">模板路径</param>
/// <returns></returns>
public static void DataTableToExcelAndDownload(DataTable dt, string excelName, string templatePath)
{
IWorkbook workbook = null;
FileStream fs = null;
IRow row = null;
ISheet sheet = null;
ICell cell = null;
ICellStyle cellStyle = null;

try
{
if (dt != null && dt.Rows.Count > 0)
{
var rowCount = dt.Rows.Count; //行数
var columnCount = dt.Columns.Count; //列数

using (fs = File.OpenRead(templatePath))
{
//大批量数据导出的时候，需要注意这样的一个问题，Excel2003格式一个sheet只支持65536行，excel 2007 就比较多，是1048576
//workbook = new HSSFWorkbook(fs);//2003版本.xls
workbook = new XSSFWorkbook(fs); // 2007版本.xlsx
}

if (workbook != null)
{
sheet = workbook.GetSheetAt(0); //读取第一个sheet

//设置每行每列的单元格,
for (var i = 0; i < rowCount; i++)
{
row = sheet.CreateRow(i + 1);
for (var j = 0; j < columnCount; j++)
{
cell = row.CreateCell(j);
var value = dt.Rows[i][j];
var bdType = value.GetType().ToString();
switch (bdType)
{
case "System.String":
cell.SetCellValue(value.ToString());
break;
case "System.DateTime": //日期类型
cell.SetCellValue(
Convert.ToDateTime(value.ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
break;
case "System.Int16": //整型
case "System.Int32":
case "System.Int64":
case "System.Byte":
var intV = 0;
int.TryParse(value.ToString(), out intV);
cell.SetCellValue(intV);
break;
case "System.Decimal": //浮点型
case "System.Double":
double doubV = 0;
double.TryParse(value.ToString(), out doubV);//格式化值
cellStyle = workbook.CreateCellStyle();
cellStyle.DataFormat = HSSFDataFormat.GetBuiltinFormat("0.00");
cell.SetCellValue(doubV);
cell.CellStyle = cellStyle;
break;
default:
cell.SetCellValue(value.ToString());
break;
}
}
}

var context = HttpContext.Current;
context.Response.Clear();
context.Response.ContentType = "application/vnd.ms-excel";
context.Response.AppendHeader("Content-Disposition", "attachment; filename=" + excelName);
using (var ms = new MemoryStream())
{
workbook.Write(ms);

long fileSize = ms.Length;
//加上设置大小下载下来的.xlsx文件打开时才不会报“Excel 已完成文件级验证和修复。此工作簿的某些部分可能已被修复或丢弃”
context.Response.AddHeader("Content-Length", fileSize.ToString());

context.Response.BinaryWrite(ms.GetBuffer());
context.ApplicationInstance.CompleteRequest();
}
}
}
}
catch (Exception ex)
{
if (fs != null)
{
fs.Close();
}
ExceptionHandling.ExceptionHandler.HandleException(ex);
}
}