easyexcel是在poi基础上开发的，那么我们就可以在easyexcel生成后，再给workbook、sheet创建样式，给个别单元格设置样式等操作。

理论来说可用，待测试。

    httpServletResponse.setContentType("application/vnd.ms-excel");
            httpServletResponse.setCharacterEncoding("utf-8");
            httpServletResponse.setHeader("Content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8") + ".xlsx");
            EasyExcel.write(httpServletResponse.getOutputStream(), exportVoClass)
                    .sheet("汇总")
                    .doWrite(voList);

            ExcelWriterSheetBuilder excelWriterSheetBuilder=new ExcelWriterSheetBuilder();
            WriteSheet writeSheet= excelWriterSheetBuilder.build();

            ExcelWriterBuilder excelWriterBuilder=EasyExcel.write(httpServletResponse.getOutputStream(), exportVoClass);
            ExcelWriter excelWriter=excelWriterBuilder.build();

            WriteContext writeContext=excelWriter.writeContext();
            WriteWorkbookHolder writeWorkbookHolder= writeContext.writeWorkbookHolder();
            Workbook workbook= writeWorkbookHolder.getWorkbook();
            Sheet sheet = workbook.getSheetAt(0);
            sheet.getWorkbook().createCellStyle();
            CellStyle cellStyle = sheet.getWorkbook().createCellStyle();
            Row row=sheet.getRow(0);

//            CellRangeAddress region = new CellRangeAddress(firstRow, lastRow, firstCol, lastCol); //初始行，终止行，初始列，终止列
//            sheet.addMergedRegion(region);