隧道MultipartFile

Question

我有一个Spring控制器，它在POST上接受一个名为FileUploadBean的类。控制器方法看起来像这样：

第一控制器：

@RequestMapping(value = "/upload", method = RequestMethod.POST)
@ResponseBody
public ResponseEntity<byte[]> uploadFile(final FileUploadBean fileUploadBean) throws IOException {
   // Some code that works fine here
} 

FileUploadBean属性之一的类型为MultipartFile。

现在，我正在尝试添加某种包装器控制器（将在另一台服务器上运行），它也接受FileUploadBean，并将请求转发给第一个控制器：

第二（包装）控制器：

@RequestMapping(value="/upload", method = RequestMethod.POST)
@ResponseBody
public ResponseEntity<byte[]> uploadImage(final FileUploadBean fileUploadBean) throws IOException {
  ResponseEntity<byte[]> response = restTemplate.postForEntity([first controller url here], fileUploadBean, byte[].class);
  return response;
}

当我向第一个控制器发送请求时：

org.springframework.http.converter.HttpMessageNotWritableException:

无法写入JSON:找不到java类的序列化程序。伊奥。FileDescriptor，并且没有发现创建BeanSerializer的属性（为了避免html" target="_blank">异常，请禁用SerializationFeature.FAIL_ON_EMPTY_BEANS））（通过引用链：com.outbrain.images.BEANS.FileUploadBean[“file”]-

我如何使这个请求工作？

Answer 1

我调试以前的答案，并发现这个解决方案没有保存文件到文件系统

    @PostMapping(value = "/upload")
public ResponseEntity<Object> upload(MultipartHttpServletRequest request) throws Exception {
    final MultiValueMap<String, Object> requestParts = new LinkedMultiValueMap<>();

    request.getParameterMap().forEach((name, value) -> requestParts.addAll(name, asList(value)));
    request.getMultiFileMap().forEach((name, value) -> {
        List<Resource> resources = value.stream().map(MultipartFile::getResource).collect(toList());
        requestParts.addAll(name, resources);
    });

    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(requestParts, request.getRequestHeaders());
    return restTemplate.exchange(ImageUrlUtils.getUploadUrl() + "?" + request.getQueryString(),
                                 request.getRequestMethod(), requestEntity, Object.class);

}

Answer 2

经过一番努力，我终于解决了这个问题。这就是我在第二个控制器中所做的：

@RequestMapping(value = "/upload", method = RequestMethod.POST)
public @ResponseBody
ResponseEntity<byte[]> uploadImage(final FileUploadBean fileUploadBean) throws Exception {
  File file = null;
  try {
    final MultiValueMap<String, Object> requestParts = new LinkedMultiValueMap<>();

    final String tmpImageFileName = IMAGE_TMP_DIR + fileUploadBean.getFile().getOriginalFilename();
    file = new File(tmpImageFileName);
    fileUploadBean.getFile().transferTo(file);
    requestParts.add("file", new FileSystemResource(tmpImageFileName));

    HttpHeaders headers = new HttpHeaders();
    headers.set("Content-Type", "multipart/form-data"); // Sending it like the client-form sends it

    ResponseEntity<byte[]> response = restTemplate.exchange(ImageUrlUtils.getUploadUrl(), HttpMethod.POST, new HttpEntity<>(requestParts, headers),
      byte[].class);

    return new ResponseEntity<>(response.getBody(), response.getStatusCode());
  } catch (Exception ex) {
    return new ResponseEntity<>((ex.getMessage).getBytes("UTF-8"),
      HttpStatus.INTERNAL_SERVER_ERROR);
  } finally {
    if (file != null && file.exists()) {
      file.delete();
    }
  }
}