Uploading retrieved files in a FTP server to mongodb collection using spring boot

I have implemented a springboot application to retrieve files from an FTP server and to download them into my local directory.

Following is the code which I used to do that.

@Configuration
public class FTPConfiguration {
    @ServiceActivator(inputChannel = "ftpMGET")
    @Bean
    public FtpOutboundGateway getFiles() {
        FtpOutboundGateway gateway = new FtpOutboundGateway(sf(), "mget", "payload");
        gateway.setAutoCreateDirectory(true);
        gateway.setLocalDirectory(new File("./downloads/"));
        gateway.setFileExistsMode(FileExistsMode.REPLACE_IF_MODIFIED);
        gateway.setFilter(new AcceptOnceFileListFilter<>());
        gateway.setOutputChannelName("fileResults");
        return gateway;
    }

   @Bean
    public MessageChannel fileResults() {
        DirectChannel channel = new DirectChannel();
        channel.addInterceptor(tap());
        return channel;
    }

    @Bean
    public WireTap tap() {
        return new WireTap("logging");
    }

    @ServiceActivator(inputChannel = "logging")
    @Bean
    public LoggingHandler logger() {
        LoggingHandler logger = new LoggingHandler(LoggingHandler.Level.INFO);
        logger.setLogExpressionString("'Files:' + payload");
        return logger;
    }

    @Bean
    public DefaultFtpSessionFactory sf() {
        DefaultFtpSessionFactory sf = new DefaultFtpSessionFactory();
        sf.setHost("localhost");
        sf.setPort(2121);
        sf.setUsername("anonymous");
        sf.setPassword("");
        return sf;
    }

    @MessagingGateway(defaultRequestChannel = "ftpMGET", defaultReplyChannel = "fileResults")
    public interface GateFile {

        List<File> mget(String directory);

    }
}

Now I need to upload these files to my MongoDB automatically, when I run this program. Can anyone please help me or guide me the steps I should follow?