spring integration : solutions/tips on connect multiple sftp server? - spring-integration

Question

My spring batch project needs to download files from multiple sftp servers.
the sftp host/port/filePath is config in application.properties file. I consider using the spring integration 'sftp out-bound gateway' to connect these servers and download files. but Im don't how to do this kind of configuration(I'm using java config, ) and make it work? i guess I need some way to define multiple session factory according to the number of sftp server info config in application.properties file.
properties file:
sftp.host=host1,host2
sftp.user=user1,user2
sftp.pwd=pwd1,pwd2
config class:
#Bean
public SessionFactory<ChannelSftp.LsEntry> sftpSessionFactory1() {
...
}
#Bean(name = "myGateway1")
#ServiceActivator(inputChannel = "sftpChannel1")
public MessageHandler handler1() {
...
}
#MessagingGateway
public interface DownloadGateway1 {
#Gateway(requestChannel = "sftpChannel1")
List<File> start(String dir);
}
#Bean(name="sftpChannel1")
public MessageChannel sftpChannel1() {
return new DirectChannel();
}

Answer 1

Right, the server is specified in the session factory, not the gateway. The framework does provide a delegating session factory, allowing it to be selected from one of the configured factories for each message sent to the gateway. See Delegating Session Factory.
EDIT
Here's an example:
#SpringBootApplication
public class So46721822Application {
public static void main(String[] args) {
SpringApplication.run(So46721822Application.class, args);
}
#Value("${sftp.name}")
private String[] names;
#Value("${sftp.host}")
private String[] hosts;
#Value("${sftp.user}")
private String[] users;
#Value("${sftp.pwd}")
private String[] pwds;
#Autowired
private DelegatingSessionFactory<?> sessionFactory;
#Autowired
private SftpGateway gateway;
#Bean
public ApplicationRunner runner() {
return args -> {
try {
this.sessionFactory.setThreadKey("one"); // use factory "one"
this.gateway.send(new File("/tmp/f.txt"));
}
finally {
this.sessionFactory.clearThreadKey();
}
};
}
#Bean
public DelegatingSessionFactory<LsEntry> sessionFactory() {
Map<Object, SessionFactory<LsEntry>> factories = new LinkedHashMap<>();
for (int i = 0; i < this.names.length; i++) {
DefaultSftpSessionFactory factory = new DefaultSftpSessionFactory();
factory.setHost(this.hosts[i]);
factory.setUser(this.users[i]);
factory.setPassword(this.pwds[i]);
factories.put(this.names[i], factory);
}
// use the first SF as the default
return new DelegatingSessionFactory<LsEntry>(factories, factories.values().iterator().next());
}
#ServiceActivator(inputChannel = "toSftp")
#Bean
public SftpMessageHandler handler() {
SftpMessageHandler handler = new SftpMessageHandler(sessionFactory());
handler.setRemoteDirectoryExpression(new LiteralExpression("foo"));
return handler;
}
#MessagingGateway(defaultRequestChannel = "toSftp")
public interface SftpGateway {
void send(File file);
}
}
with properties...
sftp.name=one,two
sftp.host=host1,host2
sftp.user=user1,user2
sftp.pwd=pwd1,pwd2