使用NPOI添加excel內容失敗（在現有excel檔案后添加數據失敗）

Question

通過click事件，在檔案中新建d:\a1.xlsx這個文件，也可以保存數據；但是重新打開，添加數據失敗！
下面使用了兩種NPOI方式，全部失敗！！沒有報錯，也沒發現問題所在。
執行后都是只能顯示如下內容，也就是說可以新建並且存入，但是，但是，但是在現有excel后添加數據失敗，請大家幫忙看看，指教！

 private void button51_Click(object sender, EventArgs e)
        {

            NPOI.XSSF.UserModel.XSSFWorkbook book = new NPOI.XSSF.UserModel.XSSFWorkbook();
            NPOI.SS.UserModel.ISheet sheet = book.CreateSheet("test_01");

            if (rowIndex == 1)       //執行一次
            {
                NPOI.SS.UserModel.IRow headerRow = sheet.CreateRow(0);
                headerRow.CreateCell(0).SetCellValue("序號");
                headerRow.CreateCell(1).SetCellValue("測試一");
                headerRow.CreateCell(2).SetCellValue("測試二");
                headerRow.CreateCell(3).SetCellValue("測試三");
                headerRow.CreateCell(4).SetCellValue("測試四");

                NPOI.SS.UserModel.IRow dataRow = sheet.CreateRow(rowIndex);
                dataRow.CreateCell(0).SetCellValue(rowIndex.ToString());
                dataRow.CreateCell(1).SetCellValue(userControl_station_status6.textbox94_int.ToString());
                dataRow.CreateCell(2).SetCellValue(userControl_station_status8.textbox93_int.ToString());
                dataRow.CreateCell(3).SetCellValue(userControl_station_status10.textbox92_int.ToString());
                dataRow.CreateCell(4).SetCellValue(userControl_station_status12.textbox91_int.ToString());
                fs = new FileStream(@"d:\a1.xlsx", FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);

                book.Write(fs);
                //fs.Flush();
                headerRow = null;
                dataRow = null;
                sheet = null;
                book.Close();
                book = null;
                book = null;
                book = null;
                fs.Close();
                fs.Dispose();
                 fs = null;
            }
            else
            {
                FileStream fs = new FileStream(@"d:\a1.xlsx", FileMode.Open, FileAccess.ReadWrite);
                XSSFWorkbook workbook = new NPOI.XSSF.UserModel.XSSFWorkbook(fs);
                ISheet sheet2 = workbook.GetSheetAt(0);//获取工作表
                IRow row = sheet2.GetRow(0); //得到表头
                row = sheet2.CreateRow((sheet2.LastRowNum + 1));//在工作表中添加一行

                row.CreateCell(0).SetCellValue("ftfyfghghvgh");
                row.CreateCell(1).SetCellValue("ftfyfghghvgh");             
                workbook.Write(fs);//写入文件
                workbook.Close();
                workbook = null;
                fs.Close();
                fs.Dispose();
                fs = null;
            }
       }









 private void button51_Click(object sender, EventArgs e)
        {

            NPOI.XSSF.UserModel.XSSFWorkbook book = new NPOI.XSSF.UserModel.XSSFWorkbook();
            NPOI.SS.UserModel.ISheet sheet = book.CreateSheet("test_01");

            if (rowIndex == 1)       //執行一次
            {
                NPOI.SS.UserModel.IRow headerRow = sheet.CreateRow(0);
                headerRow.CreateCell(0).SetCellValue("序號");
                headerRow.CreateCell(1).SetCellValue("測試一");
                headerRow.CreateCell(2).SetCellValue("測試二");
                headerRow.CreateCell(3).SetCellValue("測試三");
                headerRow.CreateCell(4).SetCellValue("測試四");

                NPOI.SS.UserModel.IRow dataRow = sheet.CreateRow(rowIndex);
                dataRow.CreateCell(0).SetCellValue(rowIndex.ToString());
                dataRow.CreateCell(1).SetCellValue(userControl_station_status6.textbox94_int.ToString());
                dataRow.CreateCell(2).SetCellValue(userControl_station_status8.textbox93_int.ToString());
                dataRow.CreateCell(3).SetCellValue(userControl_station_status10.textbox92_int.ToString());
                dataRow.CreateCell(4).SetCellValue(userControl_station_status12.textbox91_int.ToString());
                fs = new FileStream(@"d:\a1.xlsx", FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);

                book.Write(fs);
                //fs.Flush();
                headerRow = null;
                dataRow = null;
                sheet = null;
                book.Close();
                book = null;
                book = null;
                book = null;
                fs.Close();
                fs.Dispose();
                 fs = null;
            }
            else
            {



                NPOI.SS.UserModel.IRow dataRow = sheet.CreateRow(rowIndex);
                dataRow.CreateCell(0).SetCellValue(rowIndex.ToString());
                dataRow.CreateCell(1).SetCellValue(userControl_station_status6.textbox94_int.ToString());
                dataRow.CreateCell(2).SetCellValue(userControl_station_status8.textbox93_int.ToString());
                dataRow.CreateCell(3).SetCellValue(userControl_station_status10.textbox92_int.ToString());
                dataRow.CreateCell(4).SetCellValue(userControl_station_status12.textbox91_int.ToString());
                fs = new FileStream(@"d:\a1.xlsx", FileMode.Append);//写入流
                book.Write(fs);
                dataRow = null;
                sheet = null;
                book.Close();
                book = null;
                book = null;
                book = null;
                fs.Close();
                fs.Dispose();
                fs = null;
            }


            rowIndex++;


        }
    }

Answer 1

   //  方法 1
                FileStream fs = new FileStream(@"d:\a1.xlsx", FileMode.Open, FileAccess.ReadWrite);
              //  XSSFWorkbook workbook = new NPOI.XSSF.UserModel.XSSFWorkbook(fs);
                XSSFWorkbook  workbook = new XSSFWorkbook(fs);
                ISheet sheet2 = workbook.GetSheetAt(0);//获取工作表
                IRow row = sheet2.GetRow(0); //得到表头
                row = sheet2.CreateRow((sheet2.LastRowNum + 1));//在工作表中添加一行

                row.CreateCell(0).SetCellValue((sheet2.LastRowNum).ToString());
                row.CreateCell(1).SetCellValue(userControl_station_status6.textbox94_int.ToString());
                row.CreateCell(2).SetCellValue(userControl_station_status6.textbox93_int.ToString());
                row.CreateCell(3).SetCellValue(userControl_station_status6.textbox92_int.ToString());
                row.CreateCell(4).SetCellValue(userControl_station_status6.textbox91_int.ToString());

                FileStream fs2 = new FileStream(@"d:\a1.xlsx", FileMode.Create, FileAccess.Write);
                workbook.Write(fs2);

              //  workbook.Write(fs);//写入文件
                workbook.Close();
                workbook = null;
                fs.Close();
                fs.Dispose();
                fs = null;

                fs2.Close();
                fs2.Dispose();
                fs2 = null;

使用兩次“流”就能實現。分數給自己吧！