Commented Unassigned: 通过网页下载xlsx文件报错，丢失文件 [13361]

运行代码：

FileStream file = new FileStream("test.xlsx", FileMode.Open, FileAccess.Read);//读入excel模板
var workbook = new XSSFWorkbook(file);
MemoryStream ms = new MemoryStream();
workbook.Write(ms);//写入内存流
byte[] data = ms.ToArray();
HttpResponse response = System.Web.HttpContext.Current.Response;
response.Clear();
response.Charset = "UTF-8";
response.ContentType = "application/vnd-excel";
System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename=abc.xlsx"));
System.Web.HttpContext.Current.Response.BinaryWrite(data);
Comments: ** Comment from web user: skyv158 **

您好，我并不是没有操作文件，我对第一个单元格进行赋值了，只是我没贴出赋值代码，完整代码如下：
FileStream file = new FileStream("test.xlsx", FileMode.Open, FileAccess.Read);//读入excel模板
var workbook = new XSSFWorkbook(file);

ISheet sheet1 = workbook.GetSheetAt(0);
IRow row = sheet1.GetRow(0);
if (row == null) row = sheet1.CreateRow(0);
ICell cell = row.GetCell(0);
if (cell == null) cell = row.CreateCell(0);
cell.SetCellValue("测试文件");

MemoryStream ms = new MemoryStream();
workbook.Write(ms);//写入内存流
byte[] data = ms.ToArray();
HttpResponse response = System.Web.HttpContext.Current.Response;
response.Clear();
response.Charset = "UTF-8";
response.ContentType = "application/vnd-excel";
System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename=abc.xlsx"));
System.Web.HttpContext.Current.Response.BinaryWrite(data);

附件test.xlsx是源文件，附件abc.xlsx输出的文件。