Preventing connection leaks when accessing Session directly in DAO methods

Guys, 

 

as discussed during the call this morning, when retrieving a reference to the Hibernate session directly in DAO methods, like this

 

Session session = this.getSession();

 

you will quickly run into problems with connection leaks if you do not close this session afterwards. However, if the method where you access the session is wrapped in a transaction, you'll get an exception saying that the transaction failed, because the session was closed. 

 

This can be fixed by adding the @Transactional configuration below to the DAO method as well. The Propagation.REQUIRED will force the getSession method to use any existing transaction that exists, or create a new one none exists. 

 

@Transactional(propagation = Propagation.REQUIRED)

 

This means that when calling the DAO method from a service method which is already wrapped in a transaction, the getSession() call will re-use the existing, open transaction, but if you call the DAO method outside any existing transaction a new one will be created only for that method call.

 

Should you experience any issues with this approach, let us know - but from the testing I've done so far this works well.