springboot 中文件上传下载实例代码

@Controller
public class FileUploadCtrl {
 @Value("${file.upload.dir}")
 private String path;
 /**
  * 实现文件上传
  * */
 @RequestMapping(value = "/fileUpload",method = RequestMethod.POST)
 @ResponseBody
 public Map<String,Object> fileUpload(@RequestParam("fileName") MultipartFile file){
  Map<String,Object> map = new HashMap<String,Object>();
  int no = 0;
  String msg = "上传失败！";
  if(!file.isEmpty()){
   String fileName = file.getOriginalFilename();
   File dest = new File(path + "/" + fileName);
   if(!dest.getParentFile().exists()){ //判断文件父目录是否存在
    dest.getParentFile().mkdir();
   }
   try {
    file.transferTo(dest); //保存文件
    no = 1;
    msg = "上传成功！";
   } catch (IllegalStateException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  map.put("no",no);
  map.put("msg",msg);
  return map;
 }
 @RequestMapping(
   value = "/fileDownload",method = RequestMethod.GET
 )
 public ResponseEntity<?> getGwFileContent(@RequestParam String fileName,@RequestParam int flag) {
  HttpHeaders headers = new HttpHeaders();
  headers.add("Cache-Control","no-cache,no-store,must-revalidate");
  String filepath = path+"/"+fileName;;
  InputStream is = null;
  try {
   headers.add("Content-Disposition",String.format("attachment; filename="%s"",new String(fileName.getBytes("GBK"),"ISO8859-1")));
   if(flag==0){//表示获取缩略图
    File file = new File(filepath);
    filepath = path+"/xx"+fileName;
    File xxFile = new File(filepath);
    if(!xxFile.exists()){//不存在就生成缩略图
     Thumbnails.of(file).scale(0.25f).toFile(xxFile);
    }
   }
   is = new FileInputStream(new File(filepath));
  } catch (UnsupportedEncodingException e) {
   e.printStackTrace();
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  headers.add("Pragma","no-cache");
  headers.add("Expires","0");
  return ResponseEntity
    .ok()
    .headers(headers)
    .contentType(MediaType.parseMediaType("application/octet-stream"))
    .body(new InputStreamResource(is));
 }
}