Controller 작성

@Controller
public class FileUploadController {

...
@Autowired
    private final StorageService storageService;


    
    @Autowired
    public FileUploadController(StorageService storageService) {
        this.storageService = storageService;
    }


    @PostMapping("/common/fileform/upload")
    @ResponseBody
    public ResponseEntity<List<Attachment>> uploadFiles(@RequestParam("file") List<MultipartFile> files) {
        int owner_seq = 1;
        List<Attachment> attachments = new ArrayList<Attachment>();
        for (MultipartFile file : files) { 
            
            // 업로드된 파일 저장
            try { 
...
                // 파일 정보 저장
                storageService.store(file);  
  
            } catch (IOException e) {
                e.printStackTrace();
                return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
            }
        }
        return ResponseEntity.ok(attachments);
    }

파일첨부 저장을위한 서비스 부분

@Service
public class StorageService { 
    @Value("${upload.folder}")
    private String uploadFolder;
    
    private Path rootLocation;


    public StorageService() {    
        this.rootLocation = null;
    }
    
    @PostConstruct
    public void init() {
        this.rootLocation = Paths.get(uploadFolder);
    }


    private String getExtension(MultipartFile file) {
        String fileName = file.getOriginalFilename();
        String fileExtension = "";
        if (fileName != null && fileName.contains(".")) {
            fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1);
        }
        return fileExtension;
    }


    void store(MultipartFile file) throws IOException {
        String originalFilename = file.getOriginalFilename();
        String extension = this.getExtension(file);


        String filename = UUID.randomUUID().toString() + "." + extension;

        byte[] bytes = file.getBytes();
        Path filePath = Paths.get(uploadFolder + File.separator + filename);
        Files.write(filePath, bytes);

    }


    // Stream<Path> loadAll();


    public Path load(String filename) {
        return rootLocation.resolve(filename);
    }


    public Resource loadAsResource(String filename) throws MalformedURLException {
        Path file = rootLocation.resolve(filename);
        Resource resource = null;
        resource = new UrlResource(file.toUri());
        if (resource.exists() || resource.isReadable()) {
            return resource;
        }
        return resource;
    }


    public void delete(String filename) throws IOException {
        Path file = load(filename);
        Files.delete(file);
    }


    // void deleteAll();


}

설정을 위한 resources/application.properties 부분

upload.folder=C:\\Users\\H......3040\\upload
spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=10MB