DefaultLoadEventListener (Hibernate API Documentation) - Hibernate 3.2.3 正式版 API 英文文档

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org.hibernate.event.def
Class DefaultLoadEventListener

java.lang.Object
  org.hibernate.event.def.AbstractReassociateEventListener
      org.hibernate.event.def.AbstractLockUpgradeEventListener
          org.hibernate.event.def.DefaultLoadEventListener

All Implemented Interfaces:: LoadEventListener, Serializable

public class DefaultLoadEventListener
extends AbstractLockUpgradeEventListener
implements LoadEventListener

Defines the default load event listeners used by hibernate for loading entities in response to generated load events.

Author:: Steve Ebersole
See Also:: Serialized Form

Nested Class Summary

Nested classes inherited from class org.hibernate.event.LoadEventListener

LoadEventListener.LoadType

Field Summary

static LockMode DEFAULT_LOCK_MODE


static Object INCONSISTENT_RTN_CLASS_MARKER


static Object REMOVED_ENTITY_MARKER


Fields inherited from interface org.hibernate.event.LoadEventListener

GET, IMMEDIATE_LOAD, INTERNAL_LOAD_EAGER, INTERNAL_LOAD_LAZY, INTERNAL_LOAD_NULLABLE, LOAD, RELOAD

Constructor Summary

DefaultLoadEventListener()


Method Summary

protected Object doLoad(LoadEvent event, EntityPersister persister, EntityKey keyToLoad, LoadEventListener.LoadType options)
          Coordinates the efforts to load a given entity.

protected Object load(LoadEvent event, EntityPersister persister, EntityKey keyToLoad, LoadEventListener.LoadType options)
          Perfoms the load of an entity.

protected Object loadFromDatasource(LoadEvent event, EntityPersister persister, EntityKey keyToLoad, LoadEventListener.LoadType options)
          Performs the process of loading an entity from the configured underlying datasource.

protected Object loadFromSecondLevelCache(LoadEvent event, EntityPersister persister, LoadEventListener.LoadType options)
          Attempts to load the entity from the second-level cache.

protected Object loadFromSessionCache(LoadEvent event, EntityKey keyToLoad, LoadEventListener.LoadType options)
          Attempts to locate the entity in the session-level cache.

protected Object lockAndLoad(LoadEvent event, EntityPersister persister, EntityKey keyToLoad, LoadEventListener.LoadType options, SessionImplementor source)
          If the class to be loaded has been configured with a cache, then lock given id in that cache and then perform the load.

void onLoad(LoadEvent event, LoadEventListener.LoadType loadType)
          Handle the given load event.

protected Object proxyOrLoad(LoadEvent event, EntityPersister persister, EntityKey keyToLoad, LoadEventListener.LoadType options)
          Based on configured options, will either return a pre-existing proxy, generate a new proxy, or perform an actual load.

Methods inherited from class org.hibernate.event.def.AbstractLockUpgradeEventListener

upgradeLock

Methods inherited from class org.hibernate.event.def.AbstractReassociateEventListener

reassociate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

REMOVED_ENTITY_MARKER

public static final Object REMOVED_ENTITY_MARKER

INCONSISTENT_RTN_CLASS_MARKER

public static final Object INCONSISTENT_RTN_CLASS_MARKER

DEFAULT_LOCK_MODE

public static final LockMode DEFAULT_LOCK_MODE

Constructor Detail

DefaultLoadEventListener

public DefaultLoadEventListener()

Method Detail

onLoad

public void onLoad(LoadEvent event,
                   LoadEventListener.LoadType loadType)
            throws HibernateException

Handle the given load event.

Specified by:: onLoad in interface LoadEventListener

Parameters:: event - The load event to be handled.
Returns:: The result (i.e., the loaded entity).
Throws:: HibernateException

load

protected Object load(LoadEvent event,
                      EntityPersister persister,
                      EntityKey keyToLoad,
                      LoadEventListener.LoadType options)
               throws HibernateException

Perfoms the load of an entity.

Returns:: The loaded entity.
Throws:: HibernateException

proxyOrLoad

protected Object proxyOrLoad(LoadEvent event,
                             EntityPersister persister,
                             EntityKey keyToLoad,
                             LoadEventListener.LoadType options)
                      throws HibernateException

Based on configured options, will either return a pre-existing proxy, generate a new proxy, or perform an actual load.

Returns:: The result of the proxy/load operation.
Throws:: HibernateException

lockAndLoad

protected Object lockAndLoad(LoadEvent event,
                             EntityPersister persister,
                             EntityKey keyToLoad,
                             LoadEventListener.LoadType options,
                             SessionImplementor source)
                      throws HibernateException

If the class to be loaded has been configured with a cache, then lock given id in that cache and then perform the load.

Returns:: The loaded entity
Throws:: HibernateException

doLoad

protected Object doLoad(LoadEvent event,
                        EntityPersister persister,
                        EntityKey keyToLoad,
                        LoadEventListener.LoadType options)
                 throws HibernateException

Coordinates the efforts to load a given entity. First, an attempt is made to load the entity from the session-level cache. If not found there, an attempt is made to locate it in second-level cache. Lastly, an attempt is made to load it directly from the datasource.

Parameters:: event - The load event; persister - The persister for the entity being requested for load; keyToLoad - The EntityKey representing the entity to be loaded.; options - The load options.
Returns:: The loaded entity, or null.
Throws:: HibernateException

loadFromDatasource

protected Object loadFromDatasource(LoadEvent event,
                                    EntityPersister persister,
                                    EntityKey keyToLoad,
                                    LoadEventListener.LoadType options)
                             throws HibernateException

Performs the process of loading an entity from the configured underlying datasource.

Parameters:: event - The load event; persister - The persister for the entity being requested for load; keyToLoad - The EntityKey representing the entity to be loaded.; options - The load options.
Returns:: The object loaded from the datasource, or null if not found.
Throws:: HibernateException

loadFromSessionCache

protected Object loadFromSessionCache(LoadEvent event,
                                      EntityKey keyToLoad,
                                      LoadEventListener.LoadType options)
                               throws HibernateException

Attempts to locate the entity in the session-level cache.

If allowed to return nulls, then if the entity happens to be found in the session cache, we check the entity type for proper handling of entity hierarchies.

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.

Parameters:: event - The load event; keyToLoad - The EntityKey representing the entity to be loaded.; options - The load options.
Returns:: The entity from the session-level cache, or null.
Throws:: HibernateException - Generally indicates problems applying a lock-mode.

loadFromSecondLevelCache

protected Object loadFromSecondLevelCache(LoadEvent event,
                                          EntityPersister persister,
                                          LoadEventListener.LoadType options)
                                   throws HibernateException

Attempts to load the entity from the second-level cache.

Parameters:: event - The load event; persister - The persister for the entity being requested for load; options - The load options.
Returns:: The entity from the second-level cache, or null.
Throws:: HibernateException