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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.collection.spi;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collection;
import java.util.Iterator;

import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.loader.CollectionAliases;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.type.Type;

/**
 * Persistent collections are treated as value objects by Hibernate.
 * ie. they have no independent existence beyond the object holding
 * a reference to them. Unlike instances of entity classes, they are
 * automatically deleted when unreferenced and automatically become
 * persistent when held by a persistent object. Collections can be
 * passed between different objects (change "roles") and this might
 * cause their elements to move from one database table to another.
*
* Hibernate "wraps" a java collection in an instance of * PersistentCollection. This mechanism is designed to support * tracking of changes to the collection's persistent state and * lazy instantiation of collection elements. The downside is that * only certain abstract collection types are supported and any * extra semantics are lost
*
* Applications should never use classes in this package * directly, unless extending the "framework" here.
*
* Changes to structure of the collection are recorded by the * collection calling back to the session. Changes to mutable * elements (ie. composite elements) are discovered by cloning their * state when the collection is initialized and comparing at flush * time. * * @author Gavin King */ public interface PersistentCollection { /** * Get the owning entity. Note that the owner is only * set during the flush cycle, and when a new collection * wrapper is created while loading an entity. */ public Object getOwner(); /** * Set the reference to the owning entity */ public void setOwner(Object entity); /** * Is the collection empty? (don't try to initialize the collection) */ public boolean empty(); /** * After flushing, re-init snapshot state. */ public void setSnapshot(Serializable key, String role, Serializable snapshot); /** * After flushing, clear any "queued" additions, since the * database state is now synchronized with the memory state. */ public void postAction(); /** * return the user-visible collection (or array) instance */ public Object getValue(); /** * Called just before reading any rows from the JDBC result set */ public void beginRead(); /** * Called after reading all rows from the JDBC result set */ public boolean endRead(); /** * Called after initializing from cache */ public boolean afterInitialize(); /** * Could the application possibly have a direct reference to * the underlying collection implementation? */ public boolean isDirectlyAccessible(); /** * Disassociate this collection from the given session. * @return true if this was currently associated with the given session */ public boolean unsetSession(SessionImplementor currentSession); /** * Associate the collection with the given session. * @return false if the collection was already associated with the session * @throws HibernateException if the collection was already associated * with another open session */ public boolean setCurrentSession(SessionImplementor session) throws HibernateException; /** * Read the state of the collection from a disassembled cached value */ public void initializeFromCache(CollectionPersister persister, Serializable disassembled, Object owner) throws HibernateException; /** * Iterate all collection entries, during update of the database */ public Iterator entries(CollectionPersister persister); /** * Read a row from the JDBC result set */ public Object readFrom(ResultSet rs, CollectionPersister role, CollectionAliases descriptor, Object owner) throws HibernateException, SQLException; /** * Get the index of the given collection entry */ public Object getIdentifier(Object entry, int i); /** * Get the index of the given collection entry * @param persister it was more elegant before we added this... */ public Object getIndex(Object entry, int i, CollectionPersister persister); /** * Get the value of the given collection entry */ public Object getElement(Object entry); /** * Get the snapshot value of the given collection entry */ public Object getSnapshotElement(Object entry, int i); /** * Called before any elements are read into the collection, * allowing appropriate initializations to occur. * * @param persister The underlying collection persister. * @param anticipatedSize The anticipated size of the collection after initilization is complete. */ public void beforeInitialize(CollectionPersister persister, int anticipatedSize); /** * Does the current state exactly match the snapshot? */ public boolean equalsSnapshot(CollectionPersister persister) throws HibernateException; /** * Is the snapshot empty? */ public boolean isSnapshotEmpty(Serializable snapshot); /** * Disassemble the collection, ready for the cache */ public Serializable disassemble(CollectionPersister persister) throws HibernateException; /** * Do we need to completely recreate this collection when it changes? */ public boolean needsRecreate(CollectionPersister persister); /** * Return a new snapshot of the current state of the collection */ public Serializable getSnapshot(CollectionPersister persister) throws HibernateException; /** * To be called internally by the session, forcing * immediate initialization. */ public void forceInitialization() throws HibernateException; /** * Does an element exist at this entry in the collection? */ public boolean entryExists(Object entry, int i); //note that i parameter is now unused (delete it?) /** * Do we need to insert this element? */ public boolean needsInserting(Object entry, int i, Type elemType) throws HibernateException; /** * Do we need to update this element? */ public boolean needsUpdating(Object entry, int i, Type elemType) throws HibernateException; public boolean isRowUpdatePossible(); /** * Get all the elements that need deleting */ public Iterator getDeletes(CollectionPersister persister, boolean indexIsFormula) throws HibernateException; /** * Is this the wrapper for the given underlying collection instance? */ public boolean isWrapper(Object collection); /** * Is this instance initialized? */ public boolean wasInitialized(); /** * Does this instance have any "queued" additions? */ public boolean hasQueuedOperations(); /** * Iterate the "queued" additions */ public Iterator queuedAdditionIterator(); /** * Get the "queued" orphans */ public Collection getQueuedOrphans(String entityName); /** * Get the current collection key value */ public Serializable getKey(); /** * Get the current role name */ public String getRole(); /** * Is the collection unreferenced? */ public boolean isUnreferenced(); /** * Is the collection dirty? Note that this is only * reliable during the flush cycle, after the * collection elements are dirty checked against * the snapshot. */ public boolean isDirty(); /** * Clear the dirty flag, after flushing changes * to the database. */ public void clearDirty(); /** * Get the snapshot cached by the collection * instance */ public Serializable getStoredSnapshot(); /** * Mark the collection as dirty */ public void dirty(); /** * Called before inserting rows, to ensure that any surrogate keys * are fully generated */ public void preInsert(CollectionPersister persister) throws HibernateException; /** * Called after inserting a row, to fetch the natively generated id */ public void afterRowInsert(CollectionPersister persister, Object entry, int i) throws HibernateException; /** * get all "orphaned" elements */ public Collection getOrphans(Serializable snapshot, String entityName) throws HibernateException; }




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