从 rest 参数创建目录

Question

我想在一个主根目录下创建目录。我试过这段代码：private static String UPLOADED_FOLDER = "/opt/";@PostMappingpublic ResponseEntity<StringResponseDTO> uploadData(@RequestParam("file") MultipartFile file, RedirectAttributes redirectAttributes, @RequestParam("id") Integer merchant_id) throws Exception {        InputStream inputStream = file.getInputStream();    String originalName = file.getOriginalFilename();    String name = file.getName();    String contentType = file.getContentType();    long size = file.getSize();    LOG.info("name: " + name);    LOG.info("contentType: " + contentType);    LOG.info("size: " + size);    try {        byte[] bytes = file.getBytes();                   File newFile = new File(UPLOADED_FOLDER + merchant_id, file.getOriginalFilename());        LOG.info("New file location: " + newFile.getAbsolutePath()); //Log the path        Files.write(newFile.toPath(), bytes);    } catch (IOException e) {        e.printStackTrace();    }    return ResponseEntity.ok(new StringResponseDTO(originalName));}但我得到例外：2019-08-12 09:53:30,748 INFO  [stdout] (default task-79) 09:53:30.747 [default task-79] INFO  o.d.a.b.restapi.MerchantController - New file location: /opt/13/Screenshot 2019-08-01 at 14.58.59.png2019-08-12 09:53:30,749 ERROR [stderr] (default task-79) java.nio.file.NoSuchFileException: /opt/13/Screenshot 2019-08-01 at 14.58.59.png2019-08-12 09:53:30,750 ERROR [stderr] (default task-79)    at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:92)我需要将数字转换merchant_id成字符串吗？

Answer 1

我认为抛出异常是因为目录/opt/13不存在。Files.write将创建文件，但没有父目录。这是Files.write文档的一部分：

options 参数指定文件的创建或打开方式。如果不存在任何选项，则此方法的工作方式就像存在 CREATE、TRUNCATE_EXISTING 和 WRITE 选项一样。换句话说，它打开文件进行写入，如果文件不存在则创建文件，或者最初将现有的常规文件截断为 0 大小。

替换以下行

File newFile = new File(UPLOADED_FOLDER + merchant_id, file.getOriginalFilename());

LOG.info("New file location: " + newFile.getAbsolutePath()); //Log the path

Files.write(newFile.toPath(), bytes);

和

File directory = new File(UPLOADED_FOLDER, merchant_id.toString());

directory.mkdirs();

File newFile = new File(directory, file.getOriginalFilename());

LOG.info("New file location: " + newFile.getAbsolutePath()); //Log the path

Files.write(newFile.toPath(), bytes);