Как получить папку из ресурсов

Думаю вам это должно помочь:

@Service
public class YuorService {
    private static final String PATH = "/file.txt";
    private String data;
    @PostConstruct
    public void init() throws IOException {
        InputStream inputStream = getClass().getResourceAsStream(PATH);
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        data = bufferedReader.lines().collect(Collectors.joining());
        bufferedReader.close();
        inputStreamReader.close();
        inputStream.close();
    }
}

Еще есть такой вариант:

@Service
public class YourService {
    private static final String SRC = "src";
    private static final String[] PATH_TO_FILE = {"main", "resources", "file.txt"};
    private File file;
    @PostConstruct
    public void init() {
        Path path = Paths.get(SRC, PATH_TO_FILE);
        logFile = new File(path.toUri().getPath());
    }
}

Воспользуйтесь специализированным классом ClassPathResource

ClassPathResource imgFile = new ClassPathResource("/META-INF/resources/static/image/",
                Thread.currentThread().getContextClassLoader());