直接通过response把文件内容下载到客户端

HttpServletResponse response = ServletActionContext.getResponse();
OutputStream out = response.getOutputStream();
response.reset();
String fileName = DateUtil.convDate2String(new Date()) + ".xls";
response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
response.setContentType(Const.FileContentType.EXCEL);
List<VendorTopupOrder> list = this.orderManager.getOrdersWhichNeedVendorTopup(this.getExportCity());
List<File> processFiles = this.orderManager.getListFilesNeedProcess(list,this.getExportCity());
ExcelWriteUtil<VendorTopupOrder> writeUtil = new JXLWriteUtil<VendorTopupOrder>(out);
writeUtil.generateExcel(list, ExportExcelConfig.getExportBean("vendorBatchTopup"),
SessionManager.getAdminUsername());
out.close();
response.flushBuffer();