导出excel，后端返回文档流。前后端代码

后端代码，方便查看，放在一起了

/**
     * 导出报名表
     */
    @Log("导出报名表")
    @GetMapping( "/export")
    @ResponseBody
    @RequiresPermissions("platform:activity:export")
    public void export(HttpServletResponse response,@RequestParam("id") Integer id) throws Exception {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        List<ActivityEnrollInfo> list = activityService.listEnrollInfo(id);
        if (list == null || list.get(0).getEnrollNum() == 0) {
            throw new Exception("报名人数为0，无法导出！");
        }
        response.reset();
        response.setCharacterEncoding("utf-8");
        String fileName = list.get(0).getActivityName()+"报名信息";
        XSSFWorkbook wb = new XSSFWorkbook();
        XSSFSheet sheet = wb.createSheet(fileName);
        XSSFRow row = null;
        row = sheet.createRow(0);//创建第一个单元格
        row.setHeight((short) (400));
 
        row.createCell(0).setCellValue("活动名称");
        row.createCell(1).setCellValue("报名人数");
        row.createCell(2).setCellValue("学员姓名");
        row.createCell(3).setCellValue("城市");
        row.createCell(4).setCellValue("手机号");
        row.createCell(5).setCellValue("邮箱");
        row.createCell(6).setCellValue("备注");
 
        for (int i = 0; i < list.size(); i++) {
            row = sheet.createRow(i + 1);
            ActivityEnrollInfo devmonitorData = list.get(i);
            row.createCell(0).setCellValue(devmonitorData.getActivityName());
            row.createCell(1).setCellValue(devmonitorData.getEnrollNum());
            row.createCell(2).setCellValue(devmonitorData.getName());
            row.createCell(3).setCellValue(devmonitorData.getCity());
            row.createCell(4).setCellValue(devmonitorData.getMobile());
            row.createCell(5).setCellValue(devmonitorData.getEmail());
        }
        sheet.setDefaultRowHeight((short) (400));
        //列宽自适应
        for (int i = 0; i <= 13; i++) {
            sheet.autoSizeColumn(i);
        }
        response.setContentType("application/vnd.ms-excel;charset=utf-8");
        OutputStream os = null;
        try {
            os = response.getOutputStream();
            response.addHeader("Content-disposition", "attachment;filename=" + fileName + "-" + simpleDateFormat.format(new Date()) + ".xlsx");//默认Excel名称
            wb.write(os);
            os.flush();
            os.close();
            return;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return;
    }