org.hibernate.collection
Interface PersistentCollection

All Known Implementing Classes:

AbstractPersistentCollection, PersistentArrayHolder, PersistentBag, PersistentElementHolder, PersistentIdentifierBag, PersistentIndexedElementHolder, PersistentList, PersistentListElementHolder, PersistentMap, PersistentMapElementHolder, PersistentSet, PersistentSortedMap, PersistentSortedSet

public interface PersistentCollection

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

Method Summary

boolean	afterInitialize() Called after initializing from cache
void	afterRowInsert(CollectionPersister persister, Object entry, int i) Called after inserting a row, to fetch the natively generated id
void	beforeInitialize(CollectionPersister persister, int anticipatedSize) Called before any elements are read into the collection, allowing appropriate initializations to occur.
void	beginRead() Called just before reading any rows from the JDBC result set
void	clearDirty() Clear the dirty flag, after flushing changes to the database.
void	dirty() Mark the collection as dirty
Serializable	disassemble(CollectionPersister persister) Disassemble the collection, ready for the cache
boolean	empty() Is the collection empty? (don't try to initialize the collection)
boolean	endRead() Called after reading all rows from the JDBC result set
Iterator	entries(CollectionPersister persister) Iterate all collection entries, during update of the database
boolean	entryExists(Object entry, int i) Does an element exist at this entry in the collection?
boolean	equalsSnapshot(CollectionPersister persister) Does the current state exactly match the snapshot?
void	forceInitialization() To be called internally by the session, forcing immediate initialization.
Iterator	getDeletes(CollectionPersister persister, boolean indexIsFormula) Get all the elements that need deleting
Object	getElement(Object entry) Get the value of the given collection entry
Object	getIdentifier(Object entry, int i) Get the index of the given collection entry
Object	getIndex(Object entry, int i, CollectionPersister persister) Get the index of the given collection entry
Serializable	getKey() Get the current collection key value
Collection	getOrphans(Serializable snapshot, String entityName) get all "orphaned" elements
Object	getOwner() Get the owning entity.
Collection	getQueuedOrphans(String entityName) Get the "queued" orphans
String	getRole() Get the current role name
Serializable	getSnapshot(CollectionPersister persister) Return a new snapshot of the current state of the collection
Object	getSnapshotElement(Object entry, int i) Get the snapshot value of the given collection entry
Serializable	getStoredSnapshot() Get the snapshot cached by the collection instance
Object	getValue() return the user-visible collection (or array) instance
boolean	hasQueuedOperations() Does this instance have any "queued" additions?
void	initializeFromCache(CollectionPersister persister, Serializable disassembled, Object owner) Read the state of the collection from a disassembled cached value
boolean	isDirectlyAccessible() Could the application possibly have a direct reference to the underlying collection implementation?
boolean	isDirty() Is the collection dirty? Note that this is only reliable during the flush cycle, after the collection elements are dirty checked against the snapshot.
boolean	isRowUpdatePossible()
boolean	isSnapshotEmpty(Serializable snapshot) Is the snapshot empty?
boolean	isUnreferenced() Is the collection unreferenced?
boolean	isWrapper(Object collection) Is this the wrapper for the given underlying collection instance?
boolean	needsInserting(Object entry, int i, Type elemType) Do we need to insert this element?
boolean	needsRecreate(CollectionPersister persister) Do we need to completely recreate this collection when it changes?
boolean	needsUpdating(Object entry, int i, Type elemType) Do we need to update this element?
void	postAction() After flushing, clear any "queued" additions, since the database state is now synchronized with the memory state.
void	preInsert(CollectionPersister persister) Called before inserting rows, to ensure that any surrogate keys are fully generated
Iterator	queuedAdditionIterator() Iterate the "queued" additions
Object	readFrom(ResultSet rs, CollectionPersister role, CollectionAliases descriptor, Object owner) Read a row from the JDBC result set
boolean	setCurrentSession(SessionImplementor session) Associate the collection with the given session.
void	setOwner(Object entity) Set the reference to the owning entity
void	setSnapshot(Serializable key, String role, Serializable snapshot) After flushing, re-init snapshot state.
boolean	unsetSession(SessionImplementor currentSession) Disassociate this collection from the given session.
boolean	wasInitialized() Is this instance initialized?

Method Detail

getOwner

Object getOwner()

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.

setOwner

void setOwner(Object entity)

Set the reference to the owning entity

empty

boolean empty()

Is the collection empty? (don't try to initialize the collection)

setSnapshot

void setSnapshot(Serializable key,
                 String role,
                 Serializable snapshot)

After flushing, re-init snapshot state.

postAction

void postAction()

After flushing, clear any "queued" additions, since the database state is now synchronized with the memory state.

getValue

Object getValue()

return the user-visible collection (or array) instance

beginRead

void beginRead()

Called just before reading any rows from the JDBC result set

endRead

boolean endRead()

Called after reading all rows from the JDBC result set

afterInitialize

boolean afterInitialize()

Called after initializing from cache

isDirectlyAccessible

boolean isDirectlyAccessible()

Could the application possibly have a direct reference to the underlying collection implementation?

unsetSession

boolean unsetSession(SessionImplementor currentSession)

Disassociate this collection from the given session.

Returns:

true if this was currently associated with the given session

setCurrentSession

boolean setCurrentSession(SessionImplementor session)
                          throws HibernateException

Associate the collection with the given session.

Returns:

false if the collection was already associated with the session

Throws:

HibernateException - if the collection was already associated with another open session

initializeFromCache

void initializeFromCache(CollectionPersister persister,
                         Serializable disassembled,
                         Object owner)
                         throws HibernateException

Read the state of the collection from a disassembled cached value

Throws:

HibernateException

entries

Iterator entries(CollectionPersister persister)

Iterate all collection entries, during update of the database

readFrom

Object readFrom(ResultSet rs,
                CollectionPersister role,
                CollectionAliases descriptor,
                Object owner)
                throws HibernateException,
                       SQLException

Read a row from the JDBC result set

Throws:

HibernateException

SQLException

getIdentifier

Object getIdentifier(Object entry,
                     int i)

Get the index of the given collection entry

getIndex

Object getIndex(Object entry,
                int i,
                CollectionPersister persister)

Get the index of the given collection entry

Parameters:

persister - it was more elegant before we added this...

getElement

Object getElement(Object entry)

Get the value of the given collection entry

getSnapshotElement

Object getSnapshotElement(Object entry,
                          int i)

Get the snapshot value of the given collection entry

beforeInitialize

void beforeInitialize(CollectionPersister persister,
                      int anticipatedSize)

Called before any elements are read into the collection, allowing appropriate initializations to occur.

Parameters:

persister - The underlying collection persister.

anticipatedSize - The anticipated size of the collection after initilization is complete.

equalsSnapshot

boolean equalsSnapshot(CollectionPersister persister)
                       throws HibernateException

Does the current state exactly match the snapshot?

Throws:

HibernateException

isSnapshotEmpty

boolean isSnapshotEmpty(Serializable snapshot)

Is the snapshot empty?

disassemble

Serializable disassemble(CollectionPersister persister)
                         throws HibernateException

Disassemble the collection, ready for the cache

Throws:

HibernateException

needsRecreate

boolean needsRecreate(CollectionPersister persister)

Do we need to completely recreate this collection when it changes?

getSnapshot

Serializable getSnapshot(CollectionPersister persister)
                         throws HibernateException

Return a new snapshot of the current state of the collection

Throws:

HibernateException

forceInitialization

void forceInitialization()
                         throws HibernateException

To be called internally by the session, forcing immediate initialization.

Throws:

HibernateException

entryExists

boolean entryExists(Object entry,
                    int i)

Does an element exist at this entry in the collection?

needsInserting

boolean needsInserting(Object entry,
                       int i,
                       Type elemType)
                       throws HibernateException

Do we need to insert this element?

Throws:

HibernateException

needsUpdating

boolean needsUpdating(Object entry,
                      int i,
                      Type elemType)
                      throws HibernateException

Do we need to update this element?

Throws:

HibernateException

isRowUpdatePossible

boolean isRowUpdatePossible()

getDeletes

Iterator getDeletes(CollectionPersister persister,
                    boolean indexIsFormula)
                    throws HibernateException

Get all the elements that need deleting

Throws:

HibernateException

isWrapper

boolean isWrapper(Object collection)

Is this the wrapper for the given underlying collection instance?

wasInitialized

boolean wasInitialized()

Is this instance initialized?

hasQueuedOperations

boolean hasQueuedOperations()

Does this instance have any "queued" additions?

queuedAdditionIterator

Iterator queuedAdditionIterator()

Iterate the "queued" additions

getQueuedOrphans

Collection getQueuedOrphans(String entityName)

Get the "queued" orphans

getKey

Serializable getKey()

Get the current collection key value

getRole

String getRole()

Get the current role name

isUnreferenced

boolean isUnreferenced()

Is the collection unreferenced?

isDirty

boolean isDirty()

Is the collection dirty? Note that this is only reliable during the flush cycle, after the collection elements are dirty checked against the snapshot.

clearDirty

void clearDirty()

Clear the dirty flag, after flushing changes to the database.

getStoredSnapshot

Serializable getStoredSnapshot()

Get the snapshot cached by the collection instance

dirty

void dirty()

Mark the collection as dirty

preInsert

void preInsert(CollectionPersister persister)
               throws HibernateException

Called before inserting rows, to ensure that any surrogate keys are fully generated

Throws:

HibernateException

afterRowInsert

void afterRowInsert(CollectionPersister persister,
                    Object entry,
                    int i)
                    throws HibernateException

Called after inserting a row, to fetch the natively generated id

Throws:

HibernateException

getOrphans

Collection getOrphans(Serializable snapshot,
                      String entityName)
                      throws HibernateException

get all "orphaned" elements

Throws:

HibernateException