org.springframework.beans.factory.config
Class ObjectFactoryCreatingFactoryBean

java.lang.Object
  extended by org.springframework.beans.factory.config.AbstractFactoryBean
      extended by org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean
All Implemented Interfaces:
BeanFactoryAware, DisposableBean, 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, destroy, destroyInstance, 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 the population of normal bean properties but before an initialization callback such as InitializingBean.afterPropertiesSet() or a custom init-method.

Specified by:
setBeanFactory in interface BeanFactoryAware
Parameters:
beanFactory - owning BeanFactory (never 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 AbstractFactoryBean.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)


Copyright (c) 2002-2007 The Spring Framework Project.