RestTemplate required MultipartFile parameter 'file' is not present - spring

Question

I have a Spring controller which is defined like this:
#RequestMapping(method = RequestMethod.POST, value = "/upload")
#ResponseBody
public void handleFileUpload2(#RequestParam("file") MultipartFile file){
When I use postman, my request succeeds. When I use RestTemplate to make the request from another Spring service, I get the following error:
{"timestamp":1475579425804,"status":400,"error":"Bad Request","exception":"org.springframework.web.bind.MissingServletRequestParameterException","message":"Required MultipartFile parameter 'file' is not present","path":"/upload"}
Here is how I am using RestTemplate to make the request.
public void uploadFile(MultipartFile file, String url) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
body.add("file", new ByteArrayResource(file.getBytes()));
RestTemplate restTemplate = new RestTemplate();
HttpEntity requestEntity = new HttpEntity(body, headers);
restTemplate.exchange(url, method, requestEntity, String.class);
}
I'm not able to figure out what I am doing wrong here. This question seems to indicate that you need to add some xml to make it work properly, but since it works from Postman, I believe the actual problem is related to how I am making the rest call using RestTemplate.
If I print out the requestEntity I get the following:
<{file=[resource loaded from byte array]},{Content-Type=[multipart/form-data]}>
I'm using spring-web 4.1.4.RELEASE

Answer 1

Instead of
body.add("file", new ByteArrayResource(file.getBytes()));
try
body.add("file", file.getResource());
That works for me.

Answer 2

<beans:bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- setting maximum upload size -->
<beans:property name="maxUploadSize" value="100000" />
</beans:bean>
make sure you have added this code in your spring configuration file, it may work for you.

Answer 3

It's late to answer this question. But my answer may help for people who are looking for this issue.
I got a similar issue, changing the way of reading the file solved issue for me.
body.add("file",new FileSystemResource(TEST_PDF_FILE_PATH));

Answer 4

I had the same problem and this worked for me:
public void uploadFile(MultipartFile file, String url) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);
MultiValueMap<String, String> fileMap = new LinkedMultiValueMap<>();
ContentDisposition contentDisposition =
ContentDisposition
.builder("form-data")
.name("file")
.filename("stackoverflow.txt")
.build();
fileMap.add(HttpHeaders.CONTENT_DISPOSITION, contentDisposition.toString());
HttpEntity<Resource> fileEntity = new HttpEntity<>(new ByteArrayResource(file.getBytes()), fileMap);
MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
body.add("file", fileEntity);
RestTemplate restTemplate = new RestTemplate();
HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(body, headers);
restTemplate.exchange(url, HttpMethod.POST, requestEntity, String.class);
}
You can use any org.springframework.core.io.Resource.
I found this solution here: https://medium.com/red6-es/uploading-a-file-with-a-filename-with-spring-resttemplate-8ec5e7dc52ca
If you encounter 406 responses, add
headers.setAccept(List.of(MediaType.ALL));
or something more specific.