code: private Workbook exportExcelNoTemplateHandler(List<?> data, Class clazz, boolean isWriteHeader,
                                                    String sheetName, boolean isXSSF)
              throws Excel4JException {
  
          Workbook workbook;
          if (isXSSF) {
              workbook = new XSSFWorkbook();
          } else {
              workbook = new HSSFWorkbook();
          }
  
          generateSheet(workbook, data, clazz, isWriteHeader, sheetName);
  
          return workbook;
      }
docs: 单sheet数据导出