NPOI操作EXCEL合并单元格及单元格背景色

        /// <summary>
        /// XLSX
        /// </summary>
        static void CreateXLSX()
        {
            IWorkbook book = new XSSFWorkbook();
            ISheet sheet = book.CreateSheet("Sheet1");
            sheet.AddMergedRegion(new NPOI.SS.Util.CellRangeAddress(0, 3, 0, 3));//合并单元格
            ICellStyle style = book.CreateCellStyle();


            style.FillForegroundColor = NPOI.HSSF.Util.HSSFColor.Blue.Index; 
            style.FillPattern = FillPattern.SolidForeground; 
            sheet.CreateRow(5).CreateCell(5).CellStyle = style; //设置背景色
            using FileStream fileStream = new FileStream(@"C:\Users\Administrator\Desktop\MergedAndColor.xlsx", FileMode.CreateNew, FileAccess.ReadWrite);
            book.Write(fileStream);

        }
        /// <summary>
        /// XLS
        /// </summary>
        static void CreateXLS()
        {
            HSSFWorkbook book = new HSSFWorkbook();
            ISheet sheet = book.CreateSheet("Sheet1");
            sheet.AddMergedRegion(new NPOI.SS.Util.CellRangeAddress(0, 3, 0, 3));//合并单元格
            ICellStyle style = book.CreateCellStyle();


            style.FillForegroundColor = NPOI.HSSF.Util.HSSFColor.Blue.Index;

            style.FillPattern = FillPattern.SolidForeground;

            sheet.CreateRow(5).CreateCell(5).CellStyle = style;

            using FileStream fileStream = new FileStream(@"C:\Users\Administrator\Desktop\MergedAndColor.xls", FileMode.CreateNew, FileAccess.ReadWrite);
            book.Write(fileStream);
        }