How do you make SFTP Upload operation from single threaded to multithreaded?

I'm kind of new to the Multithreading approach. currently, in my code I am using ExecutorService Executors.newSingleThreadExecutor() to span a single thread that checks for files in a particular Directory if present I will fetch n files path(ex: n=5 files path) and will perform SFTP Operations of 5 files one by one. But when I have a Large number of files the single-threaded approach will take a lot of time to sftp each file one by one.

SftpUpload Service class:-

 @Autowired
 private  UploadMessageGateway gateway;

 public void uploadFile(File file) throws SftpException
  {
    try
     {
        gateway.uploadFile(file);
     }
    catch (Exception e)
     {
        logger.error(" Exception found at SftpUpload {} ",
                e.getMessage());
     } 
   }

sftp gateway:-

@MessagingGateway
public interface UploadMessageGateway
{
    @Gateway(requestChannel = "uploadfile")
    void uploadFile(File file);
}

sftp config file:-

@Bean
public SessionFactory<ChannelSftp.LsEntry>  factoryDetails() throws 
SftpException {
    DefaultSftpSessionFactory factory = new DefaultSftpSessionFactory();
    factory.setHost(host);
    factory.setPort(port);
    factory.setAllowUnknownKeys(true);
    factory.setUser(username);
    factory.setPassword(password);
    CachingSessionFactory<ChannelSftp.LsEntry> cachingSessionFactory = new CachingSessionFactory<>(factory);
    cachingSessionFactory.setTestSession(true);

    return new CachingSessionFactory<ChannelSftp.LsEntry>(factory);
}

@Bean
@ServiceActivator(inputChannel = "uploadfile")
public MessageHandler uploadHandler()
{
    SessionFactory<ChannelSftp.LsEntry>
            defaultSessionFactory= factoryDetails();
    sftpMessageHandler = new SftpMessageHandler(defaultSessionFactory);
    sftpMessageHandler.setRemoteDirectoryExpression(
            new LiteralExpression(remotePath,
                    defaultSessionFactory)));
    return sftpMessageHandler;
 }

is it a better option to use the spring-batch master-slave approach or to make use of Executors.newScheduledThreadPool(5) or is there any standard approach? your suggestions/links will be very helpful.

Thank you.