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

The Spring Framework

org.springframework.beans.factory.config
Class ResourceFactoryBean

java.lang.Object
  extended by org.springframework.beans.factory.config.ResourceFactoryBean
All Implemented Interfaces:
FactoryBean, InitializingBean

public class ResourceFactoryBean
extends Object
implements FactoryBean, InitializingBean

FactoryBean for Resource descriptors, exposing a Resource object for a specific resource location.

If used in the context of a surrounding ApplicationContext, the resolution of a resource location String will be delegated to the ApplicationContext's getResource method. Resource loading behavior will thus be specific to the context implementation.

Since:
28.12.2003
Author:
Juergen Hoeller, Rick Evans
See Also:
ResourceLoader.getResource(java.lang.String)

Constructor Summary
ResourceFactoryBean()
           
 
Method Summary
 void afterPropertiesSet()
          Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
 Object getObject()
          Return an instance (possibly shared or independent) of the object managed by this factory.
 Class getObjectType()
          Return the type of object that this FactoryBean creates, or null if not known in advance.
 boolean isSingleton()
          Is the object managed by this factory a singleton?
 void setLocation(Resource location)
          Set the resource location.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ResourceFactoryBean

public ResourceFactoryBean()
Method Detail

setLocation

public void setLocation(Resource location)
Set the resource location. Can be populated with a String value in a bean definition, to be automatically translated via ResourceLoader.getResource(java.lang.String)

This property is required.


afterPropertiesSet

public void afterPropertiesSet()
Description copied from interface: InitializingBean
Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).

This method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.

Specified by:
afterPropertiesSet in interface InitializingBean

getObject

public Object getObject()
Description copied from interface: FactoryBean
Return an instance (possibly shared or independent) of the object managed by this factory.

As with a BeanFactory, this allows support for both the Singleton and Prototype design pattern.

If this FactoryBean is not fully initialized yet at the time of the call (for example because it is involved in a circular reference), throw a corresponding FactoryBeanNotInitializedException.

As of Spring 2.0, FactoryBeans are allowed to return null objects. The factory will consider this as normal value to be used; it will not throw a FactoryBeanNotInitializedException in this case anymore. FactoryBean implementations are encouraged to throw FactoryBeanNotInitializedException themselves now, as appropriate.

Specified by:
getObject in interface FactoryBean
Returns:
an instance of the bean (can be null)
See Also:
FactoryBeanNotInitializedException

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

In the case of implementations that are creating a singleton object, this method 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)

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()

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