Package org.hibernate

Class Hibernate

java.lang.Object

org.hibernate.Hibernate

public final class Hibernate
extends Object

Various utility functions for working with proxies and lazy collection references.

Operations like isInitialized(Object) and initialize(Object) are of general purpose. But createDetachedProxy(SessionFactory, Class, Object) and createDetachedProxy(SessionFactory, Class, Object) are intended for use by generic code that must materialize an "amputated" graph of Hibernate entities. (For example, a library which deserializes entities from JSON.)

Graphs of Hibernate entities obtained from a Session are usually in an amputated form, with associations and collections replaced by proxies and lazy collections. (That is, by instances of the internal types HibernateProxy and PersistentCollection.) These objects are fully serializable using Java serialization, but can cause discomfort when working with custom serialization libraries. Therefore, this class defines operations that may be used to write code that completely removes the amputated leaves of the graph (the proxies) during serialization, and rematerializes and reattaches them during deserialization. It's possible, in principle, to use these operations, together with reflection, or with the Hibernate metamodel, to write such generic code for any given serialization library, but the details depend on what facilities the library itself offers for the program to intervene in the process of serialization and of deserialization.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Hibernate.CollectionInterface<C>	Operations for obtaining references to persistent collections of a certain type.

Method Summary

Modifier and Type	Method	Description
static <U> Hibernate.CollectionInterface<Collection<U>>	bag()	Obtain an instance of Hibernate.CollectionInterface representing persistent bags of a given element type.
static <C> Hibernate.CollectionInterface<C>	collection(Class<C> collectionClass)	Obtain an instance of Hibernate.CollectionInterface representing persistent collections of the given type.
static <T> boolean	contains(Collection<? super T> collection, T element)	Determine if the given persistent collection contains the given element, without fetching its state from the database.
static <E> E	createDetachedProxy(SessionFactory sessionFactory, Class<E> entityClass, Object id)	Obtain a detached, uninitialized reference (a proxy) for a persistent entity with the given identifier.
static <T> T	get(List<T> list, int key)	Obtain the element of the given persistent list with the given index, without fetching the state of the list from the database.
static <K,V> V	get(Map<? super K,V> map, K key)	Obtain the value associated with the given key by the given persistent map, without fetching the state of the map from the database.
static <T> Class<? extends T>	getClass(T proxy)	Get the true, underlying class of a proxied persistent class.
static void	initialize(Object proxy)	Force initialization of a proxy or persistent collection.
static boolean	isInitialized(Object proxy)	Check if the proxy or persistent collection is initialized.
static boolean	isPropertyInitialized(Object proxy, String propertyName)	Check if the property is initialized.
static <U> Hibernate.CollectionInterface<List<U>>	list()	Obtain an instance of Hibernate.CollectionInterface representing persistent lists of a given element type.
static <U,V> Hibernate.CollectionInterface<Map<U,V>>	map()	Obtain an instance of Hibernate.CollectionInterface representing persistent maps of a given key and value types.
static <U> Hibernate.CollectionInterface<Set<U>>	set()	Obtain an instance of Hibernate.CollectionInterface representing persistent sets of a given element type.
static int	size(Collection<?> collection)	Obtain the size of a persistent collection, without fetching its state from the database.
static <U,V> Hibernate.CollectionInterface<Map<U,V>>	sortedMap()	Obtain an instance of Hibernate.CollectionInterface representing sorted persistent maps of a given key and value types.
static <U> Hibernate.CollectionInterface<SortedSet<U>>	sortedSet()	Obtain an instance of Hibernate.CollectionInterface representing sorted persistent sets of a given element type.
static Object	unproxy(Object proxy)	If the given object is not a proxy, return it.
static <T> T	unproxy(T proxy, Class<T> entityClass)	If the given object is not a proxy, cast it to the given type, and return it.

Methods inherited from class java.lang.Object

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

Method Detail

initialize

public static void initialize(Object proxy)
                       throws HibernateException

Force initialization of a proxy or persistent collection. In the case of a many-valued association, only the collection itself is initialized. It is not guaranteed that the associated entities held within the collection will be initialized.

Parameters:

proxy - a persistable object, proxy, persistent collection or null

Throws:

HibernateException - if the proxy cannot be initialized at this time, for example, if the Session was closed

isInitialized

public static boolean isInitialized(Object proxy)

Check if the proxy or persistent collection is initialized.

Parameters:

proxy - a persistable object, proxy, persistent collection or null

Returns:

true if the argument is already initialized, or is not a proxy or collection

size

public static int size(Collection<?> collection)

Obtain the size of a persistent collection, without fetching its state from the database.

Parameters:

collection - a persistent collection associated with an open session

Returns:

the size of the collection

Since:

6.1.1

contains

public static <T> boolean contains(Collection<? super T> collection,
                                   T element)

Determine if the given persistent collection contains the given element, without fetching its state from the database.

Parameters:

collection - a persistent collection associated with an open session

Returns:

true if the collection does contain the given element

Since:

6.1.1

get

public static <K,V> V get(Map<? super K,V> map,
                                K key)

Obtain the value associated with the given key by the given persistent map, without fetching the state of the map from the database.

Parameters:

map - a persistent map associated with an open session

key - a key belonging to the map

Returns:

the value associated by the map with the given key

Since:

6.1.1

get

public static <T> T get(List<T> list,
                        int key)

Obtain the element of the given persistent list with the given index, without fetching the state of the list from the database.

Parameters:

list - a persistent list associated with an open session

key - an index belonging to the list

Returns:

the element of the list with the given index

Since:

6.1.1

getClass

public static <T> Class<? extends T> getClass(T proxy)

Get the true, underlying class of a proxied persistent class. This operation will initialize a proxy by side effect.

Parameters:

proxy - an entity instance or proxy

Returns:

the true class of the instance

isPropertyInitialized

public static boolean isPropertyInitialized(Object proxy,
                                            String propertyName)

Check if the property is initialized. If the named property does not exist or is not persistent, this method always returns true.

Parameters:

proxy - The potential proxy

propertyName - the name of a persistent attribute of the object

Returns:

true if the named property of the object is not listed as uninitialized; false otherwise

unproxy

public static Object unproxy(Object proxy)

If the given object is not a proxy, return it. But, if it is a proxy, ensure that the proxy is initialized, and return a direct reference to its proxied entity object.

Parameters:

proxy - an object which might be a proxy for an entity

Returns:

a reference that is never proxied

Throws:

LazyInitializationException - if this operation is called on an uninitialized proxy that is not associated with an open session.

unproxy

public static <T> T unproxy(T proxy,
                            Class<T> entityClass)

If the given object is not a proxy, cast it to the given type, and return it. But, if it is a proxy, ensure that the proxy is initialized, and return a direct reference to its proxied entity object, after casting to the given type.

Parameters:

proxy - an object which might be a proxy for an entity

entityClass - an entity type to cast to

Returns:

a reference that is never proxied

Throws:

LazyInitializationException - if this operation is called on an uninitialized proxy that is not associated with an open session.

createDetachedProxy

public static <E> E createDetachedProxy(SessionFactory sessionFactory,
                                        Class<E> entityClass,
                                        Object id)

Obtain a detached, uninitialized reference (a proxy) for a persistent entity with the given identifier. The returned proxy is not associated with any session, and cannot be initialized by calling initialize(Object). It can be used to represent a reference to the entity when working with a detached object graph.

Parameters:

sessionFactory - the session factory with which the entity is associated

entityClass - the entity class

id - the id of the persistent entity instance

Returns:

a detached uninitialized proxy

Since:

6.0

bag

public static <U> Hibernate.CollectionInterface<Collection<U>> bag()

Obtain an instance of Hibernate.CollectionInterface representing persistent bags of a given element type.

Type Parameters:

U - the element type

Since:

6.0

set

public static <U> Hibernate.CollectionInterface<Set<U>> set()

Obtain an instance of Hibernate.CollectionInterface representing persistent sets of a given element type.

Type Parameters:

U - the element type

Since:

6.0

list

public static <U> Hibernate.CollectionInterface<List<U>> list()

Obtain an instance of Hibernate.CollectionInterface representing persistent lists of a given element type.

Type Parameters:

U - the element type

Since:

6.0

map

public static <U,V> Hibernate.CollectionInterface<Map<U,V>> map()

Obtain an instance of Hibernate.CollectionInterface representing persistent maps of a given key and value types.

Type Parameters:

U - the key type

V - the value type

Since:

6.0

sortedSet

public static <U> Hibernate.CollectionInterface<SortedSet<U>> sortedSet()

Obtain an instance of Hibernate.CollectionInterface representing sorted persistent sets of a given element type.

Type Parameters:

U - the element type

Since:

6.0

sortedMap

public static <U,V> Hibernate.CollectionInterface<Map<U,V>> sortedMap()

Obtain an instance of Hibernate.CollectionInterface representing sorted persistent maps of a given key and value types.

Type Parameters:

U - the key type

V - the value type

Since:

6.0

collection

public static <C> Hibernate.CollectionInterface<C> collection(Class<C> collectionClass)

Obtain an instance of Hibernate.CollectionInterface representing persistent collections of the given type.

Parameters:

collectionClass - the Java class object representing the collection type

Since:

6.0