org.springframework.beans.factory.config
Class ObjectFactoryCreatingFactoryBean

java.lang.Object
  org.springframework.beans.factory.config.AbstractFactoryBean
      org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean

All Implemented Interfaces:

BeanFactoryAware, FactoryBean, InitializingBean

public class ObjectFactoryCreatingFactoryBean

extends AbstractFactoryBean

implements BeanFactoryAware

FactoryBean which returns a value which is an ObjectFactory that returns a bean from the BeanFactory. As such, this may be used to avoid having a client bean directly calling getBean() the BeanFactory to get a prototype bean out of the BeanFactory, a violation of inversion of control. Instead, with the use of this class, the client bean can be fed an ObjectFactory as a property which directly returns only the one target (usually prototype) bean.

A Sample config in an XML BeanFactory might look as follows:

<beans>

   <!-- Prototype bean since we have state -->
   <bean id="myService" class="a.b.c.MyService" singleton="false">
   </bean>
 
   <bean id="myServiceFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">
     <property name="targetBeanName"><idref local="myService"/></property>
   </bean> 
  
   <bean id="clientBean" class="a.b.c.MyClientBean">
     <property name="myServiceFactory"><ref local="myServiceFactory"/></property>
   </bean>

 </beans>

Since:

2004-05-11

Author:

Colin Sampaleanu

See Also:

ObjectFactory

Field Summary

Fields inherited from class org.springframework.beans.factory.config.AbstractFactoryBean

logger

Constructor Summary

ObjectFactoryCreatingFactoryBean()

Method Summary

protected Object	createInstance() Template method that subclasses must override to construct the object returned by this factory.
Class	getObjectType() Return the type of object that this FactoryBean creates, or null if not known in advance.
void	setBeanFactory(BeanFactory beanFactory) Callback that supplies the owning factory to a bean instance.
void	setTargetBeanName(String targetBeanName) Set the name of the target bean.

Methods inherited from class org.springframework.beans.factory.config.AbstractFactoryBean

afterPropertiesSet, getObject, isSingleton, setSingleton

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectFactoryCreatingFactoryBean

public ObjectFactoryCreatingFactoryBean()

Method Detail

setTargetBeanName

public void setTargetBeanName(String targetBeanName)

Set the name of the target bean. The target has to be a prototype bean.

setBeanFactory

public void setBeanFactory(BeanFactory beanFactory)

Description copied from interface: BeanFactoryAware

Callback that supplies the owning factory to a bean instance.

Invoked after population of normal bean properties but before an init callback like InitializingBean's afterPropertiesSet or a custom init-method.

Specified by:

setBeanFactory in interface BeanFactoryAware

Parameters:

beanFactory - owning BeanFactory (may not be null). The bean can immediately call methods on the factory.

See Also:

BeanInitializationException

createInstance

protected Object createInstance()

Description copied from class: AbstractFactoryBean

Template method that subclasses must override to construct the object returned by this factory.

Invoked on initialization of this FactoryBean in case of a singleton; else, on each getObject() call.

Specified by:

createInstance in class AbstractFactoryBean

Returns:

the object returned by this factory

See Also:

AbstractFactoryBean.getObject()

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

For a singleton, this 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)