当在后台获取文件或者下载文件后需要在前台显示或者自动下载，可采用如下response流的方法实现

当设置response.setHeader(“Content-Disposition”, “attachment;fileName=”+fileName);的时候会直接下载，取消的时候会自动调到浏览器新窗口实现预览，然后手动下载
参数为response和文件全路径

private void responseFileStream(HttpServletResponse response, String filePath){if(filePath.contains("%")){try {filePath = URLDecoder.decode(filePath,"UTF-8");} catch (UnsupportedEncodingException e) {}}if(filePath.contains("%")){try {filePath = URLDecoder.decode(filePath,"UTF-8");} catch (UnsupportedEncodingException e) {}}ServletOutputStream out = null;FileInputStream in = null;try {in = new FileInputStream(new File(filePath));String[] dir = filePath.split("/");String fileName = dir[dir.length-1];String[] array = fileName.split("[.]");String fileType = array[array.length-1].toLowerCase();//设置文件ContentType类型if("jpg,jepg,gif,png".contains(fileType)){//图片类型response.setContentType("image/"+fileType);}else if("pdf".contains(fileType)){//pdf类型response.setContentType("application/pdf");}else{//自动判断下载文件类型response.setContentType("multipart/form-data");}//设置文件头：最后一个参数是设置下载文件名response.setHeader("Content-Disposition", "attachment;fileName="+fileName);out = response.getOutputStream();// 读取文件流int len = 0;byte[] buffer = new byte[1024 * 10];while ((len = in.read(buffer)) != -1) {out.write(buffer, 0, len);}out.flush();} catch (FileNotFoundException e) {} catch (Exception e) {} finally {try {out.close();in.close();} catch (NullPointerException e) {} catch (Exception e) {}}}

controller:
我这里是先生成pdf，然后在前台下载

@GetMapping("/export")@ApiOperationSupport(order = 8)@ApiOperation(value = "导出pdf", notes = "传入recruitRequireList")public  void exportPdf(@ApiParam(value = "导出pdf", required = true) @RequestParam String ids, HttpServletResponse response) {recruitRequireService.exportPdf(ids,response);}

下载格式：