Application should be notified and refresh the UI to display the new state after one session flushed the changes of data. How can it be implemented? Could I register some listener to Hibernate? and how?

Have a look to the Interceptor stuff... You may catch the onUpdate()/onSave() callbacks and fire an event trapped by your GUI...

I have read about it. But the onSave() and onUpdate() is invoked before the session flush according to document. So it will get the old state when other session refresh at this time.

And the onSave() and onUpdate() is defined in Interface LifeCycle. If I want use this two method, every class persistent need implement it or inherit the class implement it. It is not I desired. I wish my persistent class clean and pure.

I think the hibernate should furnish a mechanism to notify outside when session flush. It somes like a Resource NotificationManager to notify the Listener registered. So the persistent class need not to implement the LifeCycle interface.

I have seen the mechanism used in WorkSpace of Eclipse Platform which works as a resource manager.

If you checked out the Inteceptor interface, then you probably noticed the callback methods onFlushDirty(), preFlush(), and postFlush(), right? Depending on your exact requirement, one of these methods will suffice.

I am sorry I did not read all of the document.
It is I desired.

Thanks every one for help:)