org.springframework.beans.factory.config
Class FieldRetrievingFactoryBean

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

public class FieldRetrievingFactoryBean
extends Object
implements FactoryBean, BeanNameAware, InitializingBean

FactoryBean which retrieves a static or non-static field value. Typically used for retrieving public static final constants.

Usage example:

 // standard definition for exposing a static field, specifying the "staticField" property
 <bean id="myField" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean">
   <property name="staticField"><value>java.sql.Connection.TRANSACTION_SERIALIZABLE</value></property>
 </bean>

 // convenience version that specifies a static field pattern as bean name
 <bean id="java.sql.Connection.TRANSACTION_SERIALIZABLE" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean"/>

Since:
1.1
Author:
Juergen Hoeller
See Also:
setStaticField(java.lang.String)

Constructor Summary
FieldRetrievingFactoryBean()
           
 
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.
 Class getTargetClass()
          Return the target class on which the field is defined.
 String getTargetField()
          Return the name of the field to be retrieved.
 Object getTargetObject()
          Return the target object on which the field is defined.
 boolean isSingleton()
          Is the bean managed by this factory a singleton or a prototype?
 void setBeanName(String beanName)
          The bean name of this FieldRetrievingFactoryBean will be interpreted as "staticField" pattern, if neither "targetClass" nor "targetObject" nor "targetField" have been specified.
 void setStaticField(String staticField)
          Set a fully qualified static field name to retrieve, e.g.
 void setTargetClass(Class targetClass)
          Set the target class on which the field is defined.
 void setTargetField(String targetField)
          Set the name of the field to be retrieved.
 void setTargetObject(Object targetObject)
          Set the target object on which the field is defined.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FieldRetrievingFactoryBean

public FieldRetrievingFactoryBean()
Method Detail

setTargetClass

public void setTargetClass(Class targetClass)
Set the target class on which the field is defined. Only necessary when the target field is static; else, a target object needs to be specified anyway.

See Also:
setTargetObject(java.lang.Object), setTargetField(java.lang.String)

getTargetClass

public Class getTargetClass()
Return the target class on which the field is defined.


setTargetObject

public void setTargetObject(Object targetObject)
Set the target object on which the field is defined. Only necessary when the target field is not static; else, a target class is sufficient.

See Also:
setTargetClass(java.lang.Class), setTargetField(java.lang.String)

getTargetObject

public Object getTargetObject()
Return the target object on which the field is defined.


setTargetField

public void setTargetField(String targetField)
Set the name of the field to be retrieved. Refers to either a static field or a non-static field, depending on a target object being set.

See Also:
setTargetClass(java.lang.Class), setTargetObject(java.lang.Object)

getTargetField

public String getTargetField()
Return the name of the field to be retrieved.


setStaticField

public void setStaticField(String staticField)
Set a fully qualified static field name to retrieve, e.g. "example.MyExampleClass.MY_EXAMPLE_FIELD". Convenient alternative to specifying targetClass and targetField.

See Also:
setTargetClass(java.lang.Class), setTargetField(java.lang.String)

setBeanName

public void setBeanName(String beanName)
The bean name of this FieldRetrievingFactoryBean will be interpreted as "staticField" pattern, if neither "targetClass" nor "targetObject" nor "targetField" have been specified. This allows for concise bean definitions with just an id/name.

Specified by:
setBeanName in interface BeanNameAware
Parameters:
beanName - the name of the bean in the factory

afterPropertiesSet

public void afterPropertiesSet()
throws ClassNotFoundException,
NoSuchFieldException
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:
ClassNotFoundException
NoSuchFieldException

getObject

public Object getObject()
throws IllegalAccessException
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 method returns null, the factory will consider the FactoryBean as not fully initialized and throw a corresponding FactoryBeanNotInitializedException.

Specified by:
getObject in interface FactoryBean
Returns:
an instance of the bean (should not be null; a null value will be considered as an indication of incomplete initialization)
Throws:
IllegalAccessException
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 to check for specific types of beans without instantiating objects, for example on autowiring.

For a singleton, this 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 bean managed by this factory a singleton or a prototype? 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. 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.

Specified by:
isSingleton in interface FactoryBean
Returns:
if this bean is a singleton
See Also:
FactoryBean.getObject()


Copyright (c) 2002-2007 The Spring Framework Project.