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PropertiesFactoryBean (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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org.springframework.beans.factory.config
Class PropertiesFactoryBean

java.lang.Object
  org.springframework.core.io.support.PropertiesLoaderSupport
      org.springframework.beans.factory.config.PropertiesFactoryBean

All Implemented Interfaces:

FactoryBean, InitializingBean

Direct Known Subclasses:

ResourceMapFactoryBean

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public class PropertiesFactoryBean
extends PropertiesLoaderSupport
implements FactoryBean, InitializingBean

Allows for making a properties file from a classpath location available as Properties instance in a bean factory. Can be used to populate any bean property of type Properties via a bean reference.

Supports loading from a properties file and/or setting local properties on this FactoryBean. The created Properties instance will be merged from loaded and local values. If neither a location nor local properties are set, an exception will be thrown on initialization.

Can create a singleton or a new object on each request. Default is a singleton.

Author:

Juergen Hoeller

See Also:

PropertiesLoaderSupport.setLocation(org.springframework.core.io.Resource), PropertiesLoaderSupport.setProperties(java.util.Properties), PropertiesLoaderSupport.setLocalOverride(boolean), Properties

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Field Summary

 

Fields inherited from class org.springframework.core.io.support.PropertiesLoaderSupport
logger, XML_FILE_EXTENSION

 

Constructor Summary
PropertiesFactoryBean()

 

Method Summary
void	afterPropertiesSet()           Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
protected  Object	createInstance()           Template method that subclasses may override to construct the object returned by this factory.
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	setSingleton(boolean singleton)           Set whether a shared 'singleton' Properties instance should be created, or rather a new Properties instance on each request.

 

Methods inherited from class org.springframework.core.io.support.PropertiesLoaderSupport
loadProperties, mergeProperties, setFileEncoding, setIgnoreResourceNotFound, setLocalOverride, setLocation, setLocations, setProperties, setPropertiesArray, setPropertiesPersister

 

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

 

Constructor Detail

PropertiesFactoryBean

public PropertiesFactoryBean()

Method Detail

setSingleton

public final void setSingleton(boolean singleton)

Set whether a shared 'singleton' Properties instance should be created, or rather a new Properties instance on each request.

Default is "true" (a shared singleton).

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isSingleton

public final 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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afterPropertiesSet

public final void afterPropertiesSet()
                              throws IOException

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

Throws:

IOException

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getObject

public final Object getObject()
                       throws IOException

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)

Throws:

IOException

See Also:

FactoryBeanNotInitializedException

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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)

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createInstance

protected Object createInstance()
                         throws IOException

Template method that subclasses may override to construct the object returned by this factory. The default implementation returns the plain merged Properties instance.

Invoked on initialization of this FactoryBean in case of a shared singleton; else, on each getObject() call.

Returns:

the object returned by this factory

Throws:

IOException - if an exception occured during properties loading

See Also:

PropertiesLoaderSupport.mergeProperties()

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