spring integration, how do multiple ssh / switch local user before conencte to remot server

Spring Integration doesn't do any SSH direct connection. That one is used only for SFTP protocol. And this one is handled by the DefaultSftpSessionFactory. For convenience we have a DelegatingSessionFactory which may decide which target factory to chose according a provided key. Which by default can be stored in the ThreadLocal. What you saying looks like a dynamic connection based on the provided user. Probably it can be done as a custom SessionFactory implementation which will do a lazy delegation after creating the target factory according provided credentials.