poi 导出文件

1、response设置文件类型和header

       //

• HSSFWorkbook（处理97(-2007) 的.xls）
• XSSFWorkbook（处理2007 OOXML (.xlsx) ）

        response.setHeader("Content-Disposition", "attachment; filename=" + newFilename);
        response.setContentType("application/vnd.ms-excel; charset=utf-8");

        try (OutputStream output = response.getOutputStream())
        {
            LazadaCancelOrderItemUtils.exportExcel(output, lazadaCancelOrderItems, domain);
        }

2、写文件

       // 建立新HSSFWorkbook对象 这里使用 try(){}==>try块退出时，会自动调用res.close()方法，关闭资源。
        try (XSSFWorkbook wb = new XSSFWorkbook())
        {
            // 建立新的XSSFSheet对象
            XSSFSheet sheet = wb.createSheet();

            XSSFRow titleRow = sheet.createRow(0);

            XSSFCell cell = null;

            // 表头字段列表
            String[] titles = new String[]{"归属部门", "卖家账号", "平台站点", "平台订单号", "产品标识", "产品SKU", "明细状态", "售出时间"};

            // 写表头
            for (int i = 0; i < titles.length; i++)
            {
                cell = titleRow.createCell(i);
                cell.setCellValue(titles[i]);
            }

            int rowNum = 1;
            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

            // 表数据
            for (LazadaCancelOrderItem item : lazadaCancelOrderItems)
            {
                int cellNum = 0;
                XSSFRow row = sheet.createRow(rowNum++);

                // 归属部门
                cell = row.createCell(cellNum++);
                Integer deptId = item.getDeptId();
                if (deptId != null)
                {
                    Department department = DepartmentUtils.getDepartment(deptId);
                    if (department != null)
                    {
                        cell.setCellValue(department.getDepartmentName());
                    }
                }

                // 卖家账号
                cell = row.createCell(cellNum++);
                cell.setCellValue(item.getAccount());

                // 平台站点
                cell = row.createCell(cellNum++);
                LazadaSiteEnum build = LazadaSiteEnum.build(item.getSite());
                String site = build != null ? build.display() : item.getSite();
                cell.setCellValue(site);

                // 平台订单号
                cell = row.createCell(cellNum++);
                cell.setCellValue(item.getPlatformOrderId());

                // 产品标识
                cell = row.createCell(cellNum++);
                cell.setCellValue(item.getProductId());

                // 产品SKU
                cell = row.createCell(cellNum++);
                cell.setCellValue(item.getSku());

                // 明细状态
                cell = row.createCell(cellNum++);
                cell.setCellValue(item.getStatus());

                // 售出时间
                cell = row.createCell(cellNum);
                cell.setCellValue(dateFormat.format(item.getSaleTime()));
            }

            // 写入Excel
            wb.write(output);
        }