保存之前如何更改多部分文件的名称？

Question

我一直在尝试使用相对路径和随机String重命名文件。问题是我无法更改多部分文件的名称。

@RequestMapping("/upload")
  public String upload(Model model, @RequestParam("files")MultipartFile[] files) {

    StringBuilder fileNames = new StringBuilder();
    String URL = Util.IMAGE_URL + Util.generateString();

    // Mock
    Post post = postService.getPostById(2L);
    Picture picture = new Picture();

    char[] chars = URL.toCharArray();


    for (MultipartFile file : files) {
      Path fileNameAndPAth = Paths.get(Util.UPLOAD_DIRECTORY, file.getOriginalFilename());
      fileNames.append(file.getOriginalFilename());

      // This didn't work.
      fileNames.replace(0, fileNames.length(), URL);

      System.out.println(fileNames);
      System.out.println(fileNameAndPAth);

      try {
        Files.write(fileNameAndPAth, file.getBytes());
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    model.addAttribute("message", "Successfully uploaded files " + fileNames.toString());
    // mock
    model.addAttribute("picture", postService.getPostById(post.getId()).getPictures());
    return "test/status";
    }