You're using Struts for a telnet application?  Struts is a framework for
HTTP request-response processing using HTML.  It is not designed for
telnet -- which is a completely different protocol employing an
abstraction of constant two-way dialogue.  You won't have a lot of
success integrating the two; and you'd be better off just implementing a
telnet server on top of sockets.

It's possible using shared state.  This could be a static field
somewhere, or it could be an object that you communicate to each of the
threads' Runnable instances when you create them.  Synchronization
becomes very important when you start using shared state, though, so
don't do this until you understand it well.  Doug Lea has a good book on
it.