How to configure spring integration adapters to get and put a file via SFTP

Question

I'm trying to implement the following scenario using Spring Integration:

The input channel should poll a SFTP site to get a file storing it in a local "stfp-inbound" folder. The output channel should push an existing file in a local "sftp-outbound" folder to the SFTP site. I started with the input channel. It had worked so far but it is obviously very static.

This is my config so far:

@Component
public class SftpClient {
    private static final Logger LOG = LoggerFactory.getLogger(SftpClient.class);

@Bean
public IntegrationFlow sftpInboundFlow() {
    return IntegrationFlows
        .from(Sftp.inboundAdapter(sftpSessionFactory())
                .preserveTimestamp(true)
                .remoteDirectory("data")
                .regexFilter(".*\\.txt$")
//                    .localFilenameExpression("#this.toUpperCase() + '.a'")
                .localDirectory(new File("ftp-inbound")),
             e -> e.id("sftpInboundAdapter")
                .autoStartup(true)
                .poller(Pollers.fixedDelay(5000)))
        .handle(m -> System.out.println(m.getPayload()))
        .get();
}

@Bean
public IntegrationFlow sftpOutboundFlow() {
    return IntegrationFlows.from("toSftpChannel")
        .handle(Sftp.outboundAdapter(sftpSessionFactory(), FileExistsMode.FAIL)
                     .useTemporaryFileName(false)
                     .remoteDirectory("/data")
        ).get();
}

@Bean
public SessionFactory<LsEntry> sftpSessionFactory() {
//      // with private key resource: catch MalformedURLException
//      try {
        DefaultSftpSessionFactory factory = new DefaultSftpSessionFactory(true);
        factory.setHost("myHost");
        factory.setPort(22);
        factory.setUser("myUser");
        factory.setPassword("myPassword");
//          factory.setPrivateKey(new FileUrlResource("/Users/myUser/.ssh/id_rsa"));
//          factory.setPrivateKeyPassphrase("passphrase");
        factory.setAllowUnknownKeys(true);
        return new CachingSessionFactory<LsEntry>(factory);
//      }
//      catch (MalformedURLException e) {
//          throw new IllegalArgumentException("malformed URL");
//      }
}

I need advice to make a more dynamic approach. I imagin a component class with public methods sftpGet() and sftpPut() to get and put a file, whereas the channels are created by integration flows with the required parameters that made up a SFTP transfer: hostname, port, user, password, remote dir, local dir.

How can I achieve that?

I got a good hint with a similar TCP/IP channel scenario but I couldn't transform those solution to this SFTP scenario.

Please advice!

After taking in Gary's recommendations I did the foolowing dynamic Bean:

@Component
public class DynamicSftpTemplate implements InputStreamCallback {
    private static Logger LOG = LoggerFactory.getLogger(DynamicSftpTemplate.class);

    private String localDir;
    private String localFilename;

    public void getSftpFile(String sessionId, String host, int port, String user, String password,
            String remoteDir, String remoteFilename, String localDir, String localFilename) {
        LOG.debug("getSftpFile sessionId={}", sessionId);
        ioSftpFile(GET, host, port, user, password,
                remoteDir, remoteFilename, localDir, localFilename);
    }

    public void putSftpFile(String sessionId, String host, int port, String user, String password,
            String remoteDir, String remoteFilename, String localDir, String localFilename) {
        LOG.debug("putSftpFile sessionId={}", sessionId);
        ioSftpFile(PUT, host, port, user, password,
                remoteDir, remoteFilename, localDir, localFilename);
    }

    public void rmSftpFile(String sessionId, String host, int port, String user, String password,
            String remoteDir, String remoteFilename) {
        LOG.debug("rmSftpFile sessionId={}", sessionId);
        ioSftpFile(RM, host, port, user, password, remoteDir, remoteFilename, null, null);
    }

    private void ioSftpFile(SftpOperationType op, String host, int port, String user, String password,
            String remoteDir, String remoteFilename, String localDir, String localFilename) {
        LOG.debug("ioSftpFile op={}, host={}, port={}", op, host, port);
        LOG.debug("ioSftpFile user={}, password={}", user, password);
        SftpRemoteFileTemplate template = new SftpRemoteFileTemplate(sftpSessionFactory(host, port, user, password));
        template.setFileNameExpression(new LiteralExpression(remoteDir + "/" + remoteFilename));
        template.setRemoteDirectoryExpression(new LiteralExpression(remoteDir));

        //template.afterPropertiesSet();
        this.localDir = localDir;
        this.localFilename = localFilename;
        if (op == GET) {
            // template.get(buildGetMessage(remoteDir, remoteFilename), (InputStreamCallback) this);
            template.get(remoteDir + "/" + remoteFilename, this);
        }
        else if (op == PUT) {
            template.send(buildPutMessage(remoteDir, remoteFilename), FileExistsMode.REPLACE);          
        }
        else if (op == RM) {
            template.remove(remoteDir + "/" + remoteFilename);          
        }
        else {
            throw new IllegalArgumentException("invalid sftp operation, " + op);
        }
    }

    private DefaultSftpSessionFactory sftpSessionFactory(String host, int port, String user, String password) {
        LOG.debug("sftpSessionFactory");
        DefaultSftpSessionFactory factory = new DefaultSftpSessionFactory(true);
        factory.setHost(host);
        factory.setPort(port);
        factory.setUser(user);
        factory.setPassword(password);
        factory.setAllowUnknownKeys(true);
        return factory;
    }

    private Message<?> buildPutMessage(String remoteDir, String remoteFilename) {
        return MessageBuilder.withPayload(new File(this.localDir + "/" + this.localFilename))
                .setHeader("file_remoteDirectory", remoteDir)
                .setHeader("file_remoteFile", remoteFilename)
                .build();
    }

    public void doWithInputStream(InputStream is) throws IOException {
        LOG.debug("doWithInputStream");
        String fullPathName = this.localDir + "/" + this.localFilename;
        FileWriter w = new FileWriter(fullPathName);
        IOUtils.copy(is, w, "UTF-8");
        LOG.debug("doWithInputStream file {} written", fullPathName);
        w.close();
        is.close();
    }
}

Answer 1

You can use SFTP Gateways to get and put files (amongst other operations).

Or, you can just use an SftpRemoteFileTemplate directly.