NPOI合并单元格

            var filePath = @"D:\练习\杂项\NPOI合并单元格\aaa.xlsx";
            IWorkbook workbook = null;
            ISheet sheet = null;
            using (FileStream fs = File.OpenRead(filePath))
            {
                // 2007版本
                if (filePath.IndexOf(".xlsx") > 0)
                    workbook = new XSSFWorkbook(fs);
                // 2003版本
                else if (filePath.IndexOf(".xls") > 0)
                    workbook = new HSSFWorkbook(fs);

                if (workbook != null)
                {
                    sheet = workbook.GetSheetAt(0); //读取 sheet
                    CellRangeAddress region = new CellRangeAddress(1, 2, 1, 2); //设置合并的单元格;1.开始行 2.结束行 3.开始列 4.结束列;从0开始
                    sheet.AddMergedRegion(region);
                }
                //转为字节数组
                MemoryStream stream = new MemoryStream();
                workbook.Write(stream);
                var buf = stream.ToArray();

                //保存为Excel文件
                using (FileStream fs1 = new FileStream(@"D:\练习\杂项\NPOI合并单元格\bbb.xlsx", FileMode.Create, FileAccess.Write))
                {
                    fs1.Write(buf, 0, buf.Length);
                    fs1.Flush();
                }
            }