public class

TransactionAwarePersistenceManagerFactoryProxy

extends Object
implements FactoryBean<T>
java.lang.Object
   ↳ org.springframework.orm.jdo.TransactionAwarePersistenceManagerFactoryProxy

Class Overview

Proxy for a target JDO javax.jdo.PersistenceManagerFactory, returning the current thread-bound PersistenceManager (the Spring-managed transactional PersistenceManager or the single OpenPersistenceManagerInView PersistenceManager) on getPersistenceManager(), if any.

Essentially, getPersistenceManager() calls get seamlessly forwarded to getPersistenceManager(PersistenceManagerFactory, boolean). Furthermore, PersistenceManager.close calls get forwarded to releasePersistenceManager(PersistenceManager, PersistenceManagerFactory).

The main advantage of this proxy is that it allows DAOs to work with a plain JDO PersistenceManagerFactory reference, while still participating in Spring's (or a J2EE server's) resource and transaction management. DAOs will only rely on the JDO API in such a scenario, without any Spring dependencies.

Note that the behavior of this proxy matches the behavior that the JDO spec defines for a PersistenceManagerFactory as exposed by a JCA connector, when deployed in a J2EE server. Hence, DAOs could seamlessly switch between a JNDI PersistenceManagerFactory and this proxy for a local PersistenceManagerFactory, receiving the reference through Dependency Injection. This will work without any Spring API dependencies in the DAO code!

It is usually preferable to write your JDO-based DAOs with Spring's JdoTemplate, offering benefits such as consistent data access exceptions instead of JDOExceptions at the DAO layer. However, Spring's resource and transaction management (and Dependency Injection) will work for DAOs written against the plain JDO API as well.

Of course, you can still access the target PersistenceManagerFactory even when your DAOs go through this proxy, by defining a bean reference that points directly at your target PersistenceManagerFactory bean.

See Also

Summary

Public Constructors
TransactionAwarePersistenceManagerFactoryProxy()
Public Methods
PersistenceManagerFactory getObject()
Return an instance (possibly shared or independent) of the object managed by this factory.
Class<? extends PersistenceManagerFactory> getObjectType()
Return the type of object that this FactoryBean creates, or null if not known in advance.
PersistenceManagerFactory getTargetPersistenceManagerFactory()
Return the target JDO PersistenceManagerFactory that this proxy delegates to.
boolean isSingleton()
Is the object managed by this factory a singleton? That is, will 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.

void setAllowCreate(boolean allowCreate)
Set whether the PersistenceManagerFactory proxy is allowed to create a non-transactional PersistenceManager when no transactional PersistenceManager can be found for the current thread.
void setTargetPersistenceManagerFactory(PersistenceManagerFactory target)
Set the target JDO PersistenceManagerFactory that this proxy should delegate to.
Protected Methods
boolean isAllowCreate()
Return whether the PersistenceManagerFactory proxy is allowed to create a non-transactional PersistenceManager when no transactional PersistenceManager can be found for the current thread.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.springframework.beans.factory.FactoryBean

Public Constructors

public TransactionAwarePersistenceManagerFactoryProxy ()

Public Methods

public PersistenceManagerFactory getObject ()

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.

Returns
  • an instance of the bean (can be null)

public Class<? extends PersistenceManagerFactory> getObjectType ()

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.

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

public PersistenceManagerFactory getTargetPersistenceManagerFactory ()

Return the target JDO PersistenceManagerFactory that this proxy delegates to.

public boolean isSingleton ()

Is the object managed by this factory a singleton? That is, will 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 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.

Returns
  • whether the exposed object is a singleton

public void setAllowCreate (boolean allowCreate)

Set whether the PersistenceManagerFactory proxy is allowed to create a non-transactional PersistenceManager when no transactional PersistenceManager can be found for the current thread.

Default is "true". Can be turned off to enforce access to transactional PersistenceManagers, which safely allows for DAOs written to get a PersistenceManager without explicit closing (i.e. a PersistenceManagerFactory.getPersistenceManager() call without corresponding PersistenceManager.close() call).

See Also
  • PersistenceManagerFactoryUtils#getPersistenceManager(javax.jdo.PersistenceManagerFactory, boolean)

public void setTargetPersistenceManagerFactory (PersistenceManagerFactory target)

Set the target JDO PersistenceManagerFactory that this proxy should delegate to. This should be the raw PersistenceManagerFactory, as accessed by JdoTransactionManager.

See Also

Protected Methods

protected boolean isAllowCreate ()

Return whether the PersistenceManagerFactory proxy is allowed to create a non-transactional PersistenceManager when no transactional PersistenceManager can be found for the current thread.