This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
This isn't really a Struts-related question if you're just asking how to get Hibernate sessions/session factories. There are several ways to go about it; the ORM forum might be a more appropriate place to ask.
If you're using Spring then the DAOs can be injected with session factories essentially automatically.