ObjectFactoryCreatingFactoryBean

Class Overview

A FactoryBean implementation that returns a value which is an ObjectFactory that in turn returns a bean sourced from a BeanFactory.

As such, this may be used to avoid having a client object directly calling getBean(String) to get a (typically prototype) bean from a BeanFactory, which would be a violation of the inversion of control principle. Instead, with the use of this class, the client object can be fed an ObjectFactory instance as a property which directly returns only the one target bean (again, which is typically a prototype bean).

A sample config in an XML-based BeanFactory might look as follows:

<beans>

   <!-- Prototype bean since we have state -->
   <bean id="myService" class="a.b.c.MyService" scope="prototype"/>

   <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="myServiceFactory"/>
   </bean>

</beans>

The attendant MyClientBean class implementation might look something like this:

package a.b.c;

 import org.springframework.beans.factory.ObjectFactory;

 public class MyClientBean {

   private ObjectFactory<MyService> myServiceFactory;

   public void setMyServiceFactory(ObjectFactory<MyService> myServiceFactory) {
     this.myServiceFactory = myServiceFactory;
   }

   public void someBusinessMethod() {
     // get a 'fresh', brand new MyService instance
     MyService service = this.myServiceFactory.getObject();
     // use the service object to effect the business logic...
   }
 }

An alternate approach to this application of an object creational pattern would be to use the ServiceLocatorFactoryBean to source (prototype) beans. The ServiceLocatorFactoryBean approach has the advantage of the fact that one doesn't have to depend on any Spring-specific interface such as ObjectFactory, but has the disadvantage of requiring runtime class generation. Please do consult the ServiceLocatorFactoryBean JavaDoc for a fuller discussion of this issue.

Summary

[Expand] Inherited Fields
From class org.springframework.beans.factory.config.AbstractFactoryBean protected final Log logger Logger available to subclasses

[Expand] Inherited Methods
From class org.springframework.beans.factory.config.AbstractFactoryBean void afterPropertiesSet() Eagerly create the singleton instance, if necessary. abstract T createInstance() Template method that subclasses must override to construct the object returned by this factory. void destroy() Destroy the singleton instance, if any. void destroyInstance(T instance) Callback for destroying a singleton instance. BeanFactory getBeanFactory() Return the BeanFactory that this bean runs in. TypeConverter getBeanTypeConverter() Obtain a bean type converter from the BeanFactory that this bean runs in. Class[] getEarlySingletonInterfaces() Return an array of interfaces that a singleton object exposed by this FactoryBean is supposed to implement, for use with an 'early singleton proxy' that will be exposed in case of a circular reference. final T getObject() Expose the singleton instance or create a new prototype instance. abstract Class<?> getObjectType() This abstract method declaration mirrors the method in the FactoryBean interface, for a consistent offering of abstract template methods. 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 setBeanClassLoader(ClassLoader classLoader) Callback that supplies the bean class loader to a bean instance. void setBeanFactory(BeanFactory beanFactory) Callback that supplies the owning factory to a bean instance. void setSingleton(boolean singleton) Set if a singleton should be created, or a new object on each request otherwise.
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)
From interface org.springframework.beans.factory.BeanClassLoaderAware abstract void setBeanClassLoader(ClassLoader classLoader) Callback that supplies the bean class loader to a bean instance.
From interface org.springframework.beans.factory.BeanFactoryAware abstract void setBeanFactory(BeanFactory beanFactory) Callback that supplies the owning factory to a bean instance.
From interface org.springframework.beans.factory.DisposableBean abstract void destroy() Invoked by a BeanFactory on destruction of a singleton.
From interface org.springframework.beans.factory.FactoryBean abstract T getObject() Return an instance (possibly shared or independent) of the object managed by this factory. abstract Class<?> getObjectType() Return the type of object that this FactoryBean creates, or null if not known in advance. abstract 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.
From interface org.springframework.beans.factory.InitializingBean abstract void afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).