How to upload picture in Spring and Angular2 - spring

Question

I want to upload picture in my app this is my Angular 2 code
constructor () {
this.progress = Observable.create(observer => {
this.progressObserver = observer
}).share();
}
public makeFileRequest (url: string, params: string[], files: File[]):
Observable<any> {
return Observable.create(observer => {
let formData: FormData = new FormData(),
xhr: XMLHttpRequest = new XMLHttpRequest();
for (let i = 0; i < files.length; i++) {
formData.append("uploads[]", files[i], files[i].name);
}
xhr.onreadystatechange = () => {
if (xhr.readyState === 4) {
if (xhr.status === 200) {
observer.next(JSON.parse(xhr.response));
observer.complete();
} else {
observer.error(xhr.response);
}
}
};
xhr.upload.onprogress = (event) => {
this.progress = Math.round(event.loaded / event.total * 100);
this.progressObserver.next(this.progress);
};
xhr.open('POST', url, true);
xhr.send(formData);
});
}
And this is my spring controller
#RequestMapping(value = "/upload", method = RequestMethod.POST)
#ResponseBody
public ResponseEntity<?> uploadFile(
#RequestParam("file") MultipartFile uploadfile) {
try {
// Get the filename and build the local file path (be sure that the
// application have write permissions on such directory)
String filename = uploadfile.getOriginalFilename();
String directory = "/assets/images";
String filepath = Paths.get(directory, filename).toString();
// Save the file locally
BufferedOutputStream stream =
new BufferedOutputStream(new FileOutputStream(new File(filepath)));
stream.write(uploadfile.getBytes());
stream.close();
}
catch (Exception e) {
System.out.println(e.getMessage());
return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
}
return new ResponseEntity<>(HttpStatus.OK);
}
And I get this error
ERROR {"timestamp":1498220487868,"status":400,"error":"Bad Request","exception":"org.springframework.web.multipart.support.MissingServletRequestPartException","message":"Required request part 'file' is not present","path":"/webapp/api/picture/upload"}

Answer 1

You specify #RequestParam("file"), which means Spring waits for an argument with the key file, but you append your data with the key uploads.
Also, as said by #ledniov, your are receiving an array of multipart files, not only one.
Corrections if you want to use the key file:
// Front-End: change "uploads" to "file"
formData.append("file[]", files[i], files[i].name);
// Back-End: takes a MultipartFile array
#RequestParam("file") MultipartFile[] uploadfile
Corrections if you want to use the key uploads:
// Back-End: change "file" to "uploads" and takes a MultipartFile array
#RequestParam("uploads") MultipartFile[] uploadfile