/**
* Based on configured options, will either return a pre-existing proxy, generate a new proxy, or
* perform an actual load.
*
* @return The result of the proxy/load operation.
* @throws HibernateException
*/
protected Object proxyOrLoad(
final LoadEvent event,
final EntityPersister persister,
final EntityKey keyToLoad,
final LoadEventListener.LoadType options)
throws HibernateException {
if (log.isTraceEnabled()) {
log.trace(
"loading entity: "
+ MessageHelper.infoString(
persister, event.getEntityId(), event.getSession().getFactory()));
}
if (!persister.hasProxy()) {
// this class has no proxies (so do a shortcut)
return load(event, persister, keyToLoad, options);
} else {
final PersistenceContext persistenceContext = event.getSession().getPersistenceContext();
// look for a proxy
Object proxy = persistenceContext.getProxy(keyToLoad);
if (proxy != null) {
return returnNarrowedProxy(event, persister, keyToLoad, options, persistenceContext, proxy);
} else {
if (options.isAllowProxyCreation()) {
return createProxyIfNecessary(event, persister, keyToLoad, options, persistenceContext);
} else {
// return a newly loaded object
return load(event, persister, keyToLoad, options);
}
}
}
}
/**
* Perfoms the load of an entity.
*
* @return The loaded entity.
* @throws HibernateException
*/
protected Object load(
final LoadEvent event,
final EntityPersister persister,
final EntityKey keyToLoad,
final LoadEventListener.LoadType options)
throws HibernateException {
if (event.getInstanceToLoad() != null) {
if (event.getSession().getPersistenceContext().getEntry(event.getInstanceToLoad()) != null) {
throw new PersistentObjectException(
"attempted to load into an instance that was already associated with the session: "
+ MessageHelper.infoString(
persister, event.getEntityId(), event.getSession().getFactory()));
}
persister.setIdentifier(
event.getInstanceToLoad(), event.getEntityId(), event.getSession().getEntityMode());
}
Object entity = doLoad(event, persister, keyToLoad, options);
boolean isOptionalInstance = event.getInstanceToLoad() != null;
if (!options.isAllowNulls() || isOptionalInstance) {
ObjectNotFoundException.throwIfNull(entity, event.getEntityId(), event.getEntityClassName());
}
if (isOptionalInstance && entity != event.getInstanceToLoad()) {
throw new NonUniqueObjectException(event.getEntityId(), event.getEntityClassName());
}
return entity;
}
/**
* Attempts to locate the entity in the session-level cache. If checkDeleted was set to true, then
* if the entity is found in the session-level cache, it's current status within the session cache
* is checked to see if it has previously been scheduled for deletion.
*
* @return The entity from the session-level cache, or null.
* @throws HibernateException
*/
protected Object loadFromSessionCache(
final LoadEvent event, final EntityKey keyToLoad, final LoadEventListener.LoadType options)
throws HibernateException {
SessionImplementor session = event.getSession();
Object old = session.getEntityUsingInterceptor(keyToLoad);
if (old != null) {
// this object was already loaded
EntityEntry oldEntry = session.getPersistenceContext().getEntry(old);
if (options.isCheckDeleted()) {
throwObjectDeletedIfNecessary(event, oldEntry);
}
upgradeLock(old, oldEntry, event.getLockMode(), session);
}
return old;
}
/** Given that there is a pre-existing proxy. Initialize it if necessary; narrow if necessary. */
private Object returnNarrowedProxy(
final LoadEvent event,
final EntityPersister persister,
final EntityKey keyToLoad,
final LoadEventListener.LoadType options,
final PersistenceContext persistenceContext,
final Object proxy) {
log.trace("entity proxy found in session cache");
LazyInitializer li = ((HibernateProxy) proxy).getHibernateLazyInitializer();
if (li.isUnwrap()) {
return li.getImplementation();
}
// return existing or narrowed proxy
Object impl =
options.isAllowProxyCreation() ? null : load(event, persister, keyToLoad, options);
return persistenceContext.narrowProxy(proxy, persister, keyToLoad, impl);
}
/**
* Handle the given load event.
*
* @param event The load event to be handled.
* @return The result (i.e., the loaded entity).
* @throws HibernateException
*/
public void onLoad(LoadEvent event, LoadEventListener.LoadType loadType)
throws HibernateException {
final SessionImplementor source = event.getSession();
EntityPersister persister;
if (event.getInstanceToLoad() != null) {
persister =
source.getEntityPersister(
null, event.getInstanceToLoad()); // the load() which takes an entity does not pass an
// entityName
event.setEntityClassName(event.getInstanceToLoad().getClass().getName());
} else {
persister = source.getFactory().getEntityPersister(event.getEntityClassName());
}
if (persister == null) {
throw new HibernateException("Unable to locate persister: " + event.getEntityClassName());
}
EntityKey keyToLoad = new EntityKey(event.getEntityId(), persister, source.getEntityMode());
try {
if (loadType.isNakedEntityReturned()) {
// do not return a proxy!
// (this option indicates we are initializing a proxy)
event.setResult(load(event, persister, keyToLoad, loadType));
} else {
// return a proxy if appropriate
if (event.getLockMode() == LockMode.NONE) {
event.setResult(proxyOrLoad(event, persister, keyToLoad, loadType));
} else {
event.setResult(lockAndLoad(event, persister, keyToLoad, loadType, source));
}
}
} catch (HibernateException e) {
log.info("Error performing load command", e);
throw e;
}
}
/**
* Given that there is no pre-existing proxy. Check if the entity is already loaded. If it is,
* return the entity, otherwise create and return a proxy.
*/
private Object createProxyIfNecessary(
final LoadEvent event,
final EntityPersister persister,
final EntityKey keyToLoad,
final LoadEventListener.LoadType options,
final PersistenceContext persistenceContext) {
Object existing = persistenceContext.getEntity(keyToLoad);
if (existing != null) {
// return existing object or initialized proxy (unless deleted)
log.trace("entity found in session cache");
if (options.isCheckDeleted()) {
EntityEntry entry = persistenceContext.getEntry(existing);
throwObjectDeletedIfNecessary(event, entry);
}
return existing;
} else {
log.trace("creating new proxy for entity");
// return new uninitialized proxy
Object proxy = persister.createProxy(event.getEntityId(), event.getSession());
persistenceContext.getBatchFetchQueue().addBatchLoadableEntityKey(keyToLoad);
persistenceContext.addProxy(keyToLoad, proxy);
return proxy;
}
}
