org.springframework.orm.jdo

Class TransactionAwarePersistenceManagerFactoryProxy

java.lang.Object

org.springframework.orm.jdo.TransactionAwarePersistenceManagerFactoryProxy

All Implemented Interfaces:

FactoryBean<PersistenceManagerFactory>

public class TransactionAwarePersistenceManagerFactoryProxy
extends java.lang.Object
implements FactoryBean<PersistenceManagerFactory>

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 PersistenceManagerFactoryUtils.getPersistenceManager(PersistenceManagerFactory, boolean). Furthermore, PersistenceManager.close calls get forwarded to PersistenceManagerFactoryUtils.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!

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.

Since:

1.2

Author:

Juergen Hoeller

See Also:

javax.jdo.PersistenceManagerFactory#getPersistenceManager(), javax.jdo.PersistenceManager#close(), PersistenceManagerFactoryUtils.getPersistenceManager(PersistenceManagerFactory, boolean), PersistenceManagerFactoryUtils.releasePersistenceManager(PersistenceManager, PersistenceManagerFactory)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	TransactionAwarePersistenceManagerFactoryProxy.PersistenceManagerFactoryInvocationHandler Invocation handler that delegates getPersistenceManager calls on the PersistenceManagerFactory proxy to PersistenceManagerFactoryUtils for being aware of thread-bound transactions.
private static class	TransactionAwarePersistenceManagerFactoryProxy.PersistenceManagerInvocationHandler Invocation handler that delegates close calls on PersistenceManagers to PersistenceManagerFactoryUtils for being aware of thread-bound transactions.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	allowCreate
private PersistenceManagerFactory	proxy
private PersistenceManagerFactory	target

Constructor Summary

Constructors

Constructor and Description
TransactionAwarePersistenceManagerFactoryProxy()

Method Summary

Modifier and Type	Method and Description
PersistenceManagerFactory	getObject() Return an instance (possibly shared or independent) of the object managed by this factory.
java.lang.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.
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.
boolean	isSingleton() 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)?
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.

Methods inherited from class java.lang.Object

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

Field Detail

target

private PersistenceManagerFactory target

allowCreate

private boolean allowCreate

proxy

private PersistenceManagerFactory proxy

Constructor Detail

TransactionAwarePersistenceManagerFactoryProxy

public TransactionAwarePersistenceManagerFactoryProxy()

Method Detail

setTargetPersistenceManagerFactory

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:

JdoTransactionManager

getTargetPersistenceManagerFactory

public PersistenceManagerFactory getTargetPersistenceManagerFactory()

Return the target JDO PersistenceManagerFactory that this proxy delegates to.

setAllowCreate

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)

isAllowCreate

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.

getObject

public PersistenceManagerFactory 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<PersistenceManagerFactory>

Returns:

an instance of the bean (can be null)

See Also:

FactoryBeanNotInitializedException

getObjectType

public java.lang.Class<? extends PersistenceManagerFactory> 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<PersistenceManagerFactory>

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<T>)

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<PersistenceManagerFactory>

Returns:

whether the exposed object is a singleton

See Also:

FactoryBean.getObject(), SmartFactoryBean.isPrototype()