c# excel xls保存

  public HSSFWorkbook Excel_Export(DataTable query,string title,int[] rowweight,string[] rowtitle)
        {

            HSSFWorkbook workbook = new HSSFWorkbook();
            HSSFSheet sheet = workbook.CreateSheet("Sheet1") as HSSFSheet;
            IRow row = sheet.CreateRow();
            int ii = ;

            Color c = Color.FromArgb(, , );
            HSSFPalette palette = workbook.GetCustomPalette();
            palette.SetColorAtIndex((short), c.R, c.G, c.B);
            HSSFColor cellColor = palette.FindColor(c.R, c.G, c.B);

            ICellStyle style = workbook.CreateCellStyle();
            style.Alignment = HorizontalAlignment.Center;
            style.WrapText = true;
            style.BorderLeft = BorderStyle.Thin;
            style.BorderRight = BorderStyle.Thin;
            style.BorderTop = BorderStyle.Thin;
            style.BorderBottom = BorderStyle.Thin;
            style.VerticalAlignment = VerticalAlignment.Center;
            style.FillPattern = FillPattern.SolidForeground;
            style.FillForegroundColor = cellColor.Indexed;
            IFont font = workbook.CreateFont();
            font.FontHeightInPoints = ;
            font.FontName = "微软雅黑";
            font.IsBold = true;
            style.SetFont(font);

            ICell cell = row.CreateCell(ii);

            if(!string.IsNullOrEmpty(title))
            {
                row.Height =  * ;
                cell.SetCellValue(title);
                cell.CellStyle = style;
                sheet.AddMergedRegion(new CellRangeAddress(, , , query.Columns.Count-));
                ii += ;
            }

            style = workbook.CreateCellStyle();
            style.Alignment = HorizontalAlignment.Left;
            style.WrapText = true;

            style.VerticalAlignment = VerticalAlignment.Center;
            style.BorderLeft = BorderStyle.Thin;
            style.BorderRight = BorderStyle.Thin;
            style.BorderTop = BorderStyle.Thin;
            style.BorderBottom = BorderStyle.Thin;
            style.FillPattern = FillPattern.SolidForeground;
            style.FillForegroundColor = cellColor.Indexed;
            font = workbook.CreateFont();
            font.FontHeightInPoints = ;
            font.FontName = "微软雅黑";
            style.SetFont(font);

            IRow row1 = sheet.CreateRow(ii);
            row1.Height =  * ;

            int i = ;
            if(rowtitle.Length>)
                foreach (var item in rowtitle)
                {
                    cell = row1.CreateCell(i);
                    cell.SetCellValue(item.ToString());
                    cell.CellStyle = style;
                    i += ;
                }
            else
                foreach (var item in  query.Columns)
                {
                    cell = row1.CreateCell(i);
                    cell.SetCellValue(item.ToString());
                    cell.CellStyle = style;
                    i += ;
                }

            for ( i = ; i < rowweight.Length; i++)
            {
                if (rowweight[i] > )
                {
                    row1.Cells[i].CellStyle = style; //把样式赋给单元格
                    sheet.SetColumnWidth(i, rowweight[i] * );//设置列宽
                }
            }
            i = ;
            row.Height =  * ;
            style = workbook.CreateCellStyle();
            style.WrapText = true;
            style.Alignment = HorizontalAlignment.Left;
            style.VerticalAlignment = VerticalAlignment.Center;
            style.BorderLeft = BorderStyle.Thin;
            style.BorderRight = BorderStyle.Thin;
            style.BorderTop = BorderStyle.Thin;
            style.BorderBottom = BorderStyle.Thin;
            font = workbook.CreateFont();
            font.FontHeightInPoints = ;
            font.FontName = "微软雅黑";
            style.SetFont(font);
            for (int n = ; n < query.Rows.Count; n++)
            {
                ii += ;
                IRow rowtemp = sheet.CreateRow(ii);
                for (int j = ; j < query.Columns.Count; j++)
                {
                    cell = rowtemp.CreateCell(j);
                    cell.CellStyle = style;
                    cell.SetCellValue(query.Rows[n][j]?.ToString() ?? "");  

                 }
            }
            return workbook;
        }

  //写文件
            MemoryStream ms = new MemoryStream();
            workbook.Write(ms);
            ms.Flush();
            ms.Seek(, SeekOrigin.Begin); //ms.Position = 0;

            string fileName = string.Concat(string.Format("{0:yyyyMMddHHmmssffff}", DateTime.Now), ".xls");
            return File(ms, "application/vnd.ms-excel", fileName);