使用spring RestTemplate和Jackson上传多部分文件

Question

我想通过调用rest web服务上传文件。此web服务需要MultipartFile。

我在这里读到我可以做到这一点：使用Spring Rest模板Spring Web MVC上传多部分文件

这是我的代码:

public Document uploadDocument(MultipartFile file) {
        UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(backendURL + "documents/upload");
        URI uri = builder.build().encode().toUri();

        LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
        map.add("file", file);

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
        HttpEntity<LinkedMultiValueMap<String, Object>> requestEntity =
                new HttpEntity<LinkedMultiValueMap<String, Object>>(map, headers);

        try {
            ResponseEntity<Document> responseEntity = restTemplate.exchange(uri, HttpMethod.POST, requestEntity, Document.class);
        } catch (Exception e) {
            e.getMessage(); // Crash here
        }

        return document.getBody();
    }

杰克逊尝试以JSON形式序列化该文件，但它失败了，并出现以下错误：

Could not write content: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: org.springframework.web.multipart.support.StandardMultipartFile["inputStream"]->java.io.FileInputStream["fd"])

如何禁用文件的json序列化？

Answer 1

感谢Jekin Kalariya，我找到了一个可行的解决方案。

我从我的多部分文件创建一个临时文件，并用它来创建文件系统资源。我发送此文件系统资源而不是多部分文件。

以下是工作代码：

public DocumentDetailed uploadDocumentInIfs(MultipartFile file, String userProfile) {
    UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(backendURL + "documents/upload");
    builder.queryParam("user", userProfile);
    URI uri = builder.build().encode().toUri();

    File tempFile = null;
    try {
        String extension = "." + getFileExtention(file.getOriginalFilename());
        tempFile = File.createTempFile("temp", extension);
        file.transferTo(tempFile);
    } catch (IOException e) {
        e.printStackTrace();
    }

    LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
    map.add("file", new FileSystemResource(tempFile));
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);
    HttpEntity<LinkedMultiValueMap<String, Object>> requestEntity = new HttpEntity<>(map, headers);

    Document document = null;
    try {
        ResponseEntity<Document> responseEntity =
                restTemplate.exchange(uri, HttpMethod.POST, requestEntity, Document.class);
        document = responseEntity.getBody();
    } catch (Exception e) {
        e.getMessage();
    }

    return document;
}