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java.lang.Objectorg.springframework.orm.toplink.support.TransactionAwareSessionAdapter
public class TransactionAwareSessionAdapter
This adapter FactoryBean takes a TopLink SessionFactory and exposes a corresponding transaction-aware TopLink Session as bean reference.
This adapter bean will usually be defined in front of a Spring
LocalSessionFactoryBean, to allow for passing Session references to DAOs
that expect to work on a raw TopLink Session. Your DAOs can then,
for example, access the currently active Session and UnitOfWork via
Session.getActiveSession()
and
Session.getActiveUnitOfWork()
, respectively.
The main advantage of this proxy is that it allows DAOs to work with a plain TopLink Session reference, while still participating in Spring's (or a J2EE server's) resource and transaction management. DAOs will only rely on the TopLink API in such a scenario, without any Spring dependencies.
It is usually preferable to write your TopLink-based DAOs with Spring's TopLinkTemplate, offering benefits such as consistent data access exceptions instead of TopLinkExceptions at the DAO layer. However, Spring's resource and transaction management (and Dependency Injection) will work for DAOs written against the plain TopLink API too.
Of course, you can still access the target TopLink SessionFactory even when your DAOs go through this adapter, by defining a bean reference that points directly at your target SessionFactory bean.
Note that the actual creation of a transaction-aware TopLink Session is available on the TopLink SessionFactory itself. This adapter FactoryBean is just a convenient way to expose such a Session in a declarative fashion.
LocalSessionFactoryBean
,
SessionFactory.createTransactionAwareSession()
,
Session.getActiveSession()
,
Session.getActiveUnitOfWork()
Constructor Summary | |
---|---|
TransactionAwareSessionAdapter()
|
Method Summary | |
---|---|
Object |
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 |
setSessionFactory(SessionFactory sessionFactory)
Set the SessionFactory that this adapter is supposed to expose a transaction-aware TopLink Session for. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public TransactionAwareSessionAdapter()
Method Detail |
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public void setSessionFactory(SessionFactory sessionFactory)
TopLinkTransactionManager
public Object getObject()
FactoryBean
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.
getObject
in interface FactoryBean
null
)FactoryBeanNotInitializedException
public Class getObjectType()
FactoryBean
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.
getObjectType
in interface FactoryBean
null
if not known at the time of the callListableBeanFactory.getBeansOfType(java.lang.Class)
public boolean isSingleton()
FactoryBean
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
.
isSingleton
in interface FactoryBean
FactoryBean.getObject()
,
SmartFactoryBean.isPrototype()
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