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SharedEntityManagerBean (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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org.springframework.orm.jpa.support
Class SharedEntityManagerBean

java.lang.Object
  org.springframework.orm.jpa.EntityManagerFactoryAccessor
      org.springframework.orm.jpa.support.SharedEntityManagerBean

All Implemented Interfaces:

FactoryBean, InitializingBean

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public class SharedEntityManagerBean
extends EntityManagerFactoryAccessor
implements FactoryBean, InitializingBean

FactoryBeans that exposes a shared JPA EntityManager reference for a given EntityManagerFactory. Typically used for an EntityManagerFactory created by LocalEntityManagerFactoryBean, as direct alternative to a JndiObjectFactoryBean definition for a Java EE 5 server's EntityManager.

The shared EntityManager will behave just like an EntityManager fetched from an application server's JNDI environment, as defined by the JPA specification. It will delegate all calls to the current transactional EntityManager, if any; else, it will fall back to a newly created EntityManager per operation.

Can be passed to DAOs that expect a shared EntityManager reference rather than an EntityManagerFactory reference. Note that Spring's JpaTransactionManager always needs an EntityManagerFactory reference, to be able to create new transactional EntityManager instances.

Since:

2.0

Author:

Juergen Hoeller

See Also:

EntityManagerFactoryAccessor.setEntityManagerFactory(javax.persistence.EntityManagerFactory), setEntityManagerInterface(java.lang.Class), LocalEntityManagerFactoryBean, JpaTransactionManager

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Field Summary

 

Fields inherited from class org.springframework.orm.jpa.EntityManagerFactoryAccessor
logger

 

Constructor Summary
SharedEntityManagerBean()

 

Method Summary
void	afterPropertiesSet()           Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
javax.persistence.EntityManager	getObject()           Return an instance (possibly shared or independent) of the object managed by this factory.
Class	getObjectType()           Return the type of object that this FactoryBean creates, or null if not known in advance.
boolean	isSingleton()           Is the object managed by this factory a singleton?
void	setEntityManagerInterface(Class entityManagerInterface)           Specify the EntityManager interface to expose.

 

Methods inherited from class org.springframework.orm.jpa.EntityManagerFactoryAccessor
createEntityManager, getEntityManagerFactory, getJpaPropertyMap, getTransactionalEntityManager, setEntityManagerFactory, setJpaProperties, setJpaPropertyMap

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

SharedEntityManagerBean

public SharedEntityManagerBean()

Method Detail

setEntityManagerInterface

public void setEntityManagerInterface(Class entityManagerInterface)

Specify the EntityManager interface to expose.

Default is the the EntityManager interface as defined by the EntityManagerFactoryInfo, if available. Else, the standard javax.persistence.EntityManager interface will be used.

See Also:

EntityManagerFactoryInfo.getEntityManagerInterface(), EntityManager

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afterPropertiesSet

public final void afterPropertiesSet()

Description copied from interface: InitializingBean

Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).

This method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.

Specified by:

afterPropertiesSet in interface InitializingBean

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getObject

public javax.persistence.EntityManager getObject()

Description copied from interface: FactoryBean

Return an instance (possibly shared or independent) of the object managed by this factory.

As with a BeanFactory, this allows support for both the Singleton and Prototype design pattern.

If this FactoryBean is not fully initialized yet at the time of the call (for example because it is involved in a circular reference), throw a corresponding FactoryBeanNotInitializedException.

As of Spring 2.0, FactoryBeans are allowed to return null objects. The factory will consider this as normal value to be used; it will not throw a FactoryBeanNotInitializedException in this case anymore. FactoryBean implementations are encouraged to throw FactoryBeanNotInitializedException themselves now, as appropriate.

Specified by:

getObject in interface FactoryBean

Returns:

an instance of the bean (can be null)

See Also:

FactoryBeanNotInitializedException

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getObjectType

public Class getObjectType()

Description copied from interface: FactoryBean

Return the type of object that this FactoryBean creates, or null if not known in advance.

This allows one to check for specific types of beans without instantiating objects, for example on autowiring.

In the case of implementations that are creating a singleton object, this method should try to avoid singleton creation as far as possible; it should rather estimate the type in advance. For prototypes, returning a meaningful type here is advisable too.

This method can be called before this FactoryBean has been fully initialized. It must not rely on state created during initialization; of course, it can still use such state if available.

NOTE: Autowiring will simply ignore FactoryBeans that return null here. Therefore it is highly recommended to implement this method properly, using the current state of the FactoryBean.

Specified by:

getObjectType in interface FactoryBean

Returns:

the type of object that this FactoryBean creates, or null if not known at the time of the call

See Also:

ListableBeanFactory.getBeansOfType(java.lang.Class)

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isSingleton

public boolean isSingleton()

Description copied from interface: FactoryBean

Is the object managed by this factory a singleton? That is, will FactoryBean.getObject() always return the same object (a reference that can be cached)?

NOTE: If a FactoryBean indicates to hold a singleton object, the object returned from getObject() might get cached by the owning BeanFactory. Hence, do not return true unless the FactoryBean always exposes the same reference.

The singleton status of the FactoryBean itself will generally be provided by the owning BeanFactory; usually, it has to be defined as singleton there.

NOTE: This method returning false does not necessarily indicate that returned objects are independent instances. An implementation of the extended SmartFactoryBean interface may explicitly indicate independent instances through its SmartFactoryBean.isPrototype() method. Plain FactoryBean implementations which do not implement this extended interface are simply assumed to always return independent instances if the isSingleton() implementation returns false.

Specified by:

isSingleton in interface FactoryBean

Returns:

if the exposed object is a singleton

See Also:

FactoryBean.getObject(), SmartFactoryBean.isPrototype()

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