Package org.springframework.beans.factory.config

Class AbstractFactoryBean<T>

java.lang.Object
org.springframework.beans.factory.config.AbstractFactoryBean<T>
Type Parameters:
T - the bean type
All Implemented Interfaces:
Aware, BeanClassLoaderAware, BeanFactoryAware, DisposableBean, FactoryBean<T>, InitializingBean
Direct Known Subclasses:
AbstractServiceLoaderBasedFactoryBean, ListFactoryBean, MapFactoryBean, ObjectFactoryCreatingFactoryBean, ProviderCreatingFactoryBean, SetFactoryBean, SortedResourcesFactoryBean
public abstract class AbstractFactoryBean<T> extends Object implements FactoryBean<T>, BeanClassLoaderAware, 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:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final Log
    logger
    Logger available to subclasses.

    Fields inherited from interface org.springframework.beans.factory.FactoryBean

    OBJECT_TYPE_ATTRIBUTE

  • Constructor Summary

    Constructors
    Constructor
    Description
    AbstractFactoryBean()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    afterPropertiesSet()
    Eagerly create the singleton instance, if necessary.
    protected abstract T
    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(T 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.
    final T
    getObject()
    Expose the singleton instance or create a new prototype instance.
    abstract Class<?>
    getObjectType()
    This abstract method declaration mirrors the method in the FactoryBean interface, for a consistent offering of abstract template methods.
    boolean
    isSingleton()
    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)?
    void
    setBeanClassLoader(ClassLoader classLoader)
    Callback that supplies the bean class loader to a bean instance.
    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 otherwise.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • logger

      protected final Log logger
      Logger available to subclasses.

  • Constructor Details

    • AbstractFactoryBean

      public AbstractFactoryBean()

  • Method Details

    • setSingleton

      public void setSingleton(boolean singleton)
      Set if a singleton should be created, or a new object on each request otherwise. 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.

      The default implementation returns true, since a FactoryBean typically manages a singleton instance.

      Specified by:
      isSingleton in interface FactoryBean<T>
      Returns:
      whether the exposed object is a singleton
      See Also:

    • setBeanClassLoader

      public void setBeanClassLoader(ClassLoader classLoader)
      Description copied from interface: BeanClassLoaderAware
      Callback that supplies the bean class loader to a bean instance.

      Invoked after the population of normal bean properties but before an initialization callback such as InitializingBean's InitializingBean.afterPropertiesSet() method or a custom init-method.

      Specified by:
      setBeanClassLoader in interface BeanClassLoaderAware
      Parameters:
      classLoader - the owning class loader

    • setBeanFactory

      public void setBeanFactory(@Nullable 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:

    • getBeanFactory

      @Nullable 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:

    • 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 for any other reason

    • getObject

      public final T getObject() throws Exception
      Expose the singleton instance or create a new prototype instance.
      Specified by:
      getObject in interface FactoryBean<T>
      Returns:
      an instance of the bean (can be null)
      Throws:
      Exception - in case of creation errors
      See Also:

    • 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 as well.
      See Also:

    • getObjectType

      @Nullable public abstract Class<?> getObjectType()
      This abstract method declaration mirrors the method in the FactoryBean interface, for a consistent offering of abstract template methods.
      Specified by:
      getObjectType in interface FactoryBean<T>
      Returns:
      the type of object that this FactoryBean creates, or null if not known at the time of the call
      See Also:

    • createInstance

      protected abstract T 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 occurred during object creation
      See Also:

    • getEarlySingletonInterfaces

      @Nullable 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 otherwise. 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:

    • destroyInstance

      protected void destroyInstance(@Nullable T 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: