Package org.springframework.beans.factory.config

Class FieldRetrievingFactoryBean

  • All Implemented Interfaces:
    Aware, BeanClassLoaderAware, BeanNameAware, FactoryBean<Object>, InitializingBean
    public class FieldRetrievingFactoryBean
extends Object
implements FactoryBean<Object>, BeanNameAware, BeanClassLoaderAware, 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"/>
 </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"/>

    If you are using Spring 2.0, you can also use the following style of configuration for public static fields. 

    <util:constant static-field="java.sql.Connection.TRANSACTION_SERIALIZABLE"/>
    Since:
    1.1
    Author:
    Juergen Hoeller
    See Also:
    setStaticField(java.lang.String)

    • Method Detail

      • getTargetClass

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

      • 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. Note that this name is the actual bean name used in the factory, which may differ from the originally specified name: in particular for inner bean names, the actual bean name might have been made unique through appending "#..." suffixes. Use the BeanFactoryUtils.originalBeanName(String) method to extract the original bean name (without suffix), if desired.

      • 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 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<Object>
        Returns:
        an instance of the bean (can be null)
        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 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<Object>
        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<T>)

      • 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<Object>
        Returns:
        whether the exposed object is a singleton
        See Also:
        FactoryBean.getObject(), SmartFactoryBean.isPrototype()