파일업로드로직 메소드

@Service
public class FileUploadLogic {
	public List<BoardFileDTO> uploadFiles(List<MultipartFile> multipartFiles, String path) throws IllegalStateException, IOException {
				System.out.println("originalFilename ===> "+originalFilename);
				multipartFile.transferTo(new File(path+File.separator+storeFilename));  //path서버가 인식하는 위치
				System.out.println("storeFilename ---> "+storeFilename);
				filedtolist.add(new BoardFileDTO(originalFilename, storeFilename));
			}
		}
		return filedtolist;
	}
	private String createStoreFilename(String originalFilename) { //fdsfs.jpg => pos:5, ext:jpg
		int pos = originalFilename.lastIndexOf(".");
		String ext = originalFilename.substring(pos+1);
		String uuid = UUID.randomUUID().toString(); 
		return uuid+"."+ext;
	}
}