252 APPENDIX A n MORE ADVANCED FEATURES (Personal web server) APPENDIX
252 APPENDIX A n MORE ADVANCED FEATURES APPENDIX A n MORE ADVANCED FEATURES By obtaining a JDBC connection from the session, it is of course possible to invoke stored procedures directly; however, you must be aware that the Hibernate session cache cannot track these updates. Events Hibernate 3 actually implements most of its functionality as event listeners. When you register a listener with Hibernate, the listener entirely supplants the default functionality. For example, the EJB 3 specific behavior required when using an EntityManager is achieved by plugging in a set of EJB 3 specific event listeners! If you look at the methods of the SessionImpl class, which is the internal Hibernate implementation of the Session interface, you ll see why this is the case. Most of the methods have a form very similar to that shown in Listing A-21. Listing A-21. The Implementation of a Typical Method in SessionImpl SaveOrUpdateEvent event = new SaveOrUpdateEvent(entityName, obj, this); listeners.getSaveOrUpdateEventListener().onSaveOrUpdate(event); The listeners field is an instance of SessionEventListenerConfig, which provides the requested event listener, or the default if none is specified. So, if your event listener is provided and doesn t call the default one, nothing else can. Event listeners are always registered globally for the event that they handle. You can register them in the configuration file or programmatically. Either way, you will need to map your implementation of one of the interfaces to the associated types, which you can look up in Table A-1. (The names are almost but not quite standardized.) Table A-1. The Listener Names and Their Corresponding Interfaces Type Name Listener auto-flush AutoFlushEventListener delete DeleteEventListener dirty-check DirtyCheckEventListener evict EvictEventListener flush FlushEventListener flush-entity FlushEntityEventListener load LoadEventListener load-collection InitializeCollectionEventListener lock LockEventListener merge MergeEventListener persist PersistEventListener post-delete PostDeleteEventListener post-insert PostInsertEventListener post-load PostLoadEventListener post-update PostUpdateEventListener
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