使用 responseentity进行文件的下载

// 根据文件id 进行文件的下载
 @RequestMapping("/downloadFile/{id}")
    public ResponseEntity<InputStreamResource> downFile(@PathVariable("id") String id) throws Exception{
      // 根据文件 id 从数据库中查询出文件的一些基本信息
        SysFileImportEntity sysFileImportEntity=sysFileImportService.selectById(id);
        if(sysFileImportEntity!=null){
          // 文件的原始名称
            String fileName=sysFileImportEntity.getOrginFileName();
            // 文件在服务器上存放的路径
            String filePath=sysFileImportEntity.getFilePath();
            File file = new File(filePath);
            InputStream inputStream = new FileInputStream(file);
            InputStreamResource inputStreamResource = new InputStreamResource(inputStream);
            HttpHeaders headers = new HttpHeaders();
            if(sysFileImportEntity.getTemplateName().equals("solutionAudioUploadList")){
                headers.add("Accept-Ranges", "bytes");
            }
            headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
            headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", URLEncoder.encode(fileName,"UTF-8")));
            headers.add("Pragma", "no-cache");
            headers.add("Expires", "0");
            return ResponseEntity
                    .ok()
                    .headers(headers)
                    .contentLength(file.length())
                    .contentType(MediaType.parseMediaType("application/octet-stream"))
                    .body(inputStreamResource);
        }else {
            InputStream inputStream = new ByteArrayInputStream("<script language=\"javascript\">alert('文件不存在！');</script>".getBytes("GBK"));
            InputStreamResource inputStreamResource = new InputStreamResource(inputStream);
            HttpHeaders headers = new HttpHeaders();
            headers.add(HttpHeaders.CONTENT_TYPE,"text/html;charset=UTF-8");
            headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
            headers.add("Pragma", "no-cache");
            headers.add("Expires", "0");
            return ResponseEntity
                    .ok()
                    .headers(headers)
                    .contentType(MediaType.TEXT_HTML)
                    .body(inputStreamResource);
        }
    }