Uploading a List of MultipartFile with Spring 4 restTemplate (Java Client & RestController)

Question

I am trying to post of List of MultipartFile to my RestController using spring restTemplate although I\'m a bit confused as to the exact syntax & types to use for my cli

Answer 1

It looks like the request payload that you are sending from FileUploadClient does not match what's server is expecting. Could you try changing the following:

MultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
for(MultipartFile file : multiPartFileList) {
    map.add(file.getName(), new ByteArrayResource(file.getBytes()));
}

to

MultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
List<ByteArrayResource> files = new ArrayList<>();
for(MultipartFile file : multiPartFileList) {
    files.add(new ByteArrayResource(file.getBytes()));
}
map.put("files", files);

Also, could you try changing the server's method signature to the following:

public ResponseEntity<?> uploadFiles(@RequestParam("files") List<MultipartFile> files, HttpServletRequest request) {

Update

While uploading multiple files, you need to make sure getFileName of ByteArrayResource returns same value every time. If not, you will always get an empty array.

E.g. the following works for me:

Client:

MultiValueMap<String, Object> data = new LinkedMultiValueMap<String, Object>(); 
for(MultipartFile file : multiPartFileList) { 
    ByteArrayResource resource = new ByteArrayResource(file.getBytes()) { 
        @Override 
        public String getFilename() { 
            return ""; 
        } 
    }; 
    data.add("files", resource);
} 

Server

public ResponseEntity<?> upload(@RequestParam("files") MultipartFile[] files){