Class AbstractFactoryBean<T>
- java.lang.Object
- org.springframework.beans.factory.config.AbstractFactoryBean<T>
- All Implemented Interfaces:
Aware,BeanClassLoaderAware,BeanFactoryAware,DisposableBean,FactoryBean<T>,InitializingBean
- Direct Known Subclasses:
AbstractServiceLoaderBasedFactoryBean,ListFactoryBean,MapFactoryBean,ObjectFactoryCreatingFactoryBean,ProviderCreatingFactoryBean,SetFactoryBean,SortedResourcesFactoryBean
public abstract class AbstractFactoryBean<T> extends Object implements FactoryBean<T>, BeanClassLoaderAware, BeanFactoryAware, InitializingBean, DisposableBean
Simple template superclass forFactoryBeanimplementations that creates a singleton or a prototype object, depending on a flag.If the "singleton" flag is
true(the default), this class will create the object that it creates exactly once on initialization and subsequently return said singleton instance on all calls to thegetObject()method.Else, this class will create a new instance every time the
getObject()method is invoked. Subclasses are responsible for implementing the abstractcreateInstance()template method to actually create the object(s) to expose.- Since:
- 1.0.2
- Author:
- Juergen Hoeller, Keith Donald
- See Also:
setSingleton(boolean),createInstance()
Constructor Summary
Constructors Constructor Description AbstractFactoryBean()
Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description voidafterPropertiesSet()Eagerly create the singleton instance, if necessary.protected abstract TcreateInstance()Template method that subclasses must override to construct the object returned by this factory.voiddestroy()Destroy the singleton instance, if any.protected voiddestroyInstance(T instance)Callback for destroying a singleton instance.protected BeanFactorygetBeanFactory()Return the BeanFactory that this bean runs in.protected TypeConvertergetBeanTypeConverter()Obtain a bean type converter from the BeanFactory that this bean runs in.protected 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.TgetObject()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.booleanisSingleton()Is the object managed by this factory a singleton? That is, willFactoryBean.getObject()always return the same object (a reference that can be cached)?voidsetBeanClassLoader(ClassLoader classLoader)Callback that supplies the beanclass loaderto a bean instance.voidsetBeanFactory(BeanFactory beanFactory)Callback that supplies the owning factory to a bean instance.voidsetSingleton(boolean singleton)Set if a singleton should be created, or a new object on each request otherwise.
Constructor Detail
AbstractFactoryBean
public AbstractFactoryBean()
Method Detail
setSingleton
public void setSingleton(boolean singleton)
Set if a singleton should be created, or a new object on each request otherwise. Default istrue(a singleton).
isSingleton
public boolean isSingleton()
Description copied from interface:FactoryBeanIs the object managed by this factory a singleton? That is, willFactoryBean.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 returntrueunless 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
falsedoes not necessarily indicate that returned objects are independent instances. An implementation of the extendedSmartFactoryBeaninterface may explicitly indicate independent instances through itsSmartFactoryBean.isPrototype()method. PlainFactoryBeanimplementations which do not implement this extended interface are simply assumed to always return independent instances if theisSingleton()implementation returnsfalse.- Specified by:
isSingletonin interfaceFactoryBean<T>- Returns:
- whether the exposed object is a singleton
- See Also:
FactoryBean.getObject(),SmartFactoryBean.isPrototype()
setBeanClassLoader
public void setBeanClassLoader(ClassLoader classLoader)
Description copied from interface:BeanClassLoaderAwareCallback that supplies the beanclass loaderto a bean instance.Invoked after the population of normal bean properties but before an initialization callback such as
InitializingBean'sInitializingBean.afterPropertiesSet()method or a custom init-method.- Specified by:
setBeanClassLoaderin interfaceBeanClassLoaderAware- Parameters:
classLoader- the owning class loader; may benullin which case a defaultClassLoadermust be used, for example theClassLoaderobtained viaClassUtils.getDefaultClassLoader()
setBeanFactory
public void setBeanFactory(BeanFactory beanFactory)
Description copied from interface:BeanFactoryAwareCallback 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:
setBeanFactoryin interfaceBeanFactoryAware- Parameters:
beanFactory- owning BeanFactory (nevernull). The bean can immediately call methods on the factory.- See Also:
BeanInitializationException
getBeanFactory
protected BeanFactory getBeanFactory()
Return the BeanFactory that this bean runs in.
getBeanTypeConverter
protected TypeConverter getBeanTypeConverter()
Obtain a bean type converter from the BeanFactory that this bean runs in. This is typically a fresh instance for each call, since TypeConverters are usually not thread-safe.Falls back to a SimpleTypeConverter when not running in a BeanFactory.
afterPropertiesSet
public void afterPropertiesSet() throws Exception
Eagerly create the singleton instance, if necessary.- Specified by:
afterPropertiesSetin interfaceInitializingBean- Throws:
Exception- in the event of misconfiguration (such as failure to set an essential property) or if initialization fails for any other reason
getObject
public final T getObject() throws Exception
Expose the singleton instance or create a new prototype instance.- Specified by:
getObjectin interfaceFactoryBean<T>- Returns:
- an instance of the bean (can be
null) - Throws:
Exception- in case of creation errors- See Also:
createInstance(),getEarlySingletonInterfaces()
destroy
public void destroy() throws Exception
Destroy the singleton instance, if any.- Specified by:
destroyin interfaceDisposableBean- Throws:
Exception- in case of shutdown errors. Exceptions will get logged but not rethrown to allow other beans to release their resources as well.- See Also:
destroyInstance(Object)
getObjectType
public abstract Class<?> getObjectType()
This abstract method declaration mirrors the method in the FactoryBean interface, for a consistent offering of abstract template methods.- Specified by:
getObjectTypein interfaceFactoryBean<T>- Returns:
- the type of object that this FactoryBean creates, or
nullif not known at the time of the call - See Also:
FactoryBean.getObjectType()
createInstance
protected abstract T createInstance() throws Exception
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.- Returns:
- the object returned by this factory
- Throws:
Exception- if an exception occurred during object creation- See Also:
getObject()
getEarlySingletonInterfaces
protected 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.The default implementation returns this FactoryBean's object type, provided that it is an interface, or
nullotherwise. The latter indicates that early singleton access is not supported by this FactoryBean. This will lead to a FactoryBeanNotInitializedException getting thrown.- Returns:
- the interfaces to use for 'early singletons', or
nullto indicate a FactoryBeanNotInitializedException - See Also:
FactoryBeanNotInitializedException
destroyInstance
protected void destroyInstance(T instance) throws Exception
Callback for destroying a singleton instance. Subclasses may override this to destroy the previously created instance.The default implementation is empty.
- Parameters:
instance- the singleton instance, as returned bycreateInstance()- Throws:
Exception- in case of shutdown errors- See Also:
createInstance()