AbstractFactoryBean (Spring Framework API 2.0) - Spring Framework 2.0.5 API 文档英文版

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org.springframework.beans.factory.config
Class AbstractFactoryBean

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

All Implemented Interfaces:: BeanFactoryAware, DisposableBean, FactoryBean, InitializingBean

Direct Known Subclasses:: ListFactoryBean, MapFactoryBean, ObjectFactoryCreatingFactoryBean, SetFactoryBean

public abstract class AbstractFactoryBean
extends Object
implements FactoryBean, BeanFactoryAware, InitializingBean, DisposableBean
extends Object
implements FactoryBean, BeanFactoryAware, InitializingBean, DisposableBean

Simple template superclass for FactoryBean implementations 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 the getObject() method.

Else, this class will create a new instance every time the getObject() method is invoked. Subclasses are responsible for implementing the abstract createInstance() template method to actually create the object(s) to expose.

Since:: 1.0.2
Author:: Juergen Hoeller, Keith Donald
See Also:: setSingleton(boolean), createInstance()

Field Summary

protected Log logger
          Logger available to subclasses

Constructor Summary

AbstractFactoryBean()


Method Summary

void afterPropertiesSet()
          Eagerly create the singleton instance, if necessary.

protected abstract Object createInstance()
          Template method that subclasses must override to construct the object returned by this factory.

void destroy()
          Destroy the singleton instance, if any.

protected void destroyInstance(Object instance)
          Callback for destroying a singleton instance.

protected BeanFactory getBeanFactory()
          Return the BeanFactory that this bean runs in.

protected TypeConverter getBeanTypeConverter()
          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.

Object getObject()
          Expose the singleton instance or create a new prototype instance.

abstract Class getObjectType()
          This abstract method declaration shadows the method in the FactoryBean interface.

boolean isSingleton()
          Is the object managed by this factory a singleton?

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 else.

Methods inherited from class java.lang.Object

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

Field Summary
`protected Log`	`logger` Logger available to subclasses

Constructor Summary
`AbstractFactoryBean()`

Method Summary
`void`	`afterPropertiesSet()` Eagerly create the singleton instance, if necessary.
`protected abstract Object`	`createInstance()` Template method that subclasses must override to construct the object returned by this factory.
`void`	`destroy()` Destroy the singleton instance, if any.
`protected void`	`destroyInstance(Object instance)` Callback for destroying a singleton instance.
`protected BeanFactory`	`getBeanFactory()` Return the BeanFactory that this bean runs in.
`protected TypeConverter`	`getBeanTypeConverter()` 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.
`Object`	`getObject()` Expose the singleton instance or create a new prototype instance.
`abstract Class`	`getObjectType()` This abstract method declaration shadows the method in the FactoryBean interface.
`boolean`	`isSingleton()` Is the object managed by this factory a singleton?
`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 else.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

logger

protected final Log logger

Logger available to subclasses

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 else. Default is true (a singleton).

isSingleton

public boolean isSingleton()

Description copied from interface: FactoryBean

Is the object managed by this factory a singleton? That is, will 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.

Specified by:: isSingleton in interface FactoryBean

Returns:: if the exposed object is a singleton
See Also:: FactoryBean.getObject(), SmartFactoryBean.isPrototype()

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

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.

See Also:: ConfigurableBeanFactory.getTypeConverter(), SimpleTypeConverter

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Eagerly create the singleton instance, if necessary.

Specified by:: afterPropertiesSet in interface InitializingBean

Throws:: Exception - in the event of misconfiguration (such as failure to set an essential property) or if initialization fails.

getObject

public final Object getObject()
                       throws Exception

Expose the singleton instance or create a new prototype instance.

Specified by:: getObject in interface FactoryBean

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:: destroy in interface DisposableBean

Throws:: Exception - in case of shutdown errors. Exceptions will get logged but not rethrown to allow other beans to release their resources too.
See Also:: destroyInstance(Object)

getObjectType

public abstract Class getObjectType()

This abstract method declaration shadows the method in the FactoryBean interface. This is necessary to make the getEarlySingletonInterfaces implementation in this class work on Sun's JDK 1.3 classic VM, which can't find the method when executing getEarlySingletonInterfaces else.

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:: FactoryBean.getObjectType(), getEarlySingletonInterfaces()

createInstance

protected abstract Object 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 occured 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 null else. 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 null to indicate a FactoryBeanNotInitializedException
See Also:: FactoryBeanNotInitializedException

destroyInstance

protected void destroyInstance(Object 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 by createInstance()
Throws:: Exception - in case of shutdown errors
See Also:: createInstance()