Why hibernate session.close() does not flushes the data automatically?

问题

When hibernate closes a session, the purpose of close is basically to close the underlying connection and the clean up the first level cache. Why the flush also does not happens automatically here?

回答1:

From a transactional point of view, flushing is very different from closing the session and flush should occur inside the boundaries of a transaction (or at commit time):

Ending a Session usually involves four distinct phases:

• flush the session
• commit the transaction
• close the session
• handle exceptions

On the other hand, closing a Session (and the underlying connection) should be done after a transaction has ended (the behavior of a pending transaction when closing a connection is undefined).

There is thus no reason to do anything on close and to promote bad semantics and it makes perfect sense to have distinct operations.

To sum up:

1. just use a transaction and proper demarcation as you're supposed to (and the session will get flushed at commit time if required, depending on the FlushMode).
2. use SessionFactory#getCurrentSession() and you won't have to Session#close() yourself (the Session will get closed for you at commit time).

来源：https://stackoverflow.com/questions/1969109/why-hibernate-session-close-does-not-flushes-the-data-automatically