org.springframework.beans.factory.support
Class DefaultSingletonBeanRegistry

java.lang.Object
  org.springframework.core.SimpleAliasRegistry
      org.springframework.beans.factory.support.DefaultSingletonBeanRegistry

All Implemented Interfaces:

SingletonBeanRegistry, AliasRegistry

Direct Known Subclasses:

FactoryBeanRegistrySupport

public class DefaultSingletonBeanRegistry
extends SimpleAliasRegistry
implements SingletonBeanRegistry

Generic registry for shared bean instances, implementing the SingletonBeanRegistry. Allows for registering singleton instances that should be shared for all callers of the registry, to be obtained via bean name.

Also supports registration of DisposableBean instances, (which might or might not correspond to registered singletons), to be destroyed on shutdown of the registry. Dependencies between beans can be registered to enforce an appropriate shutdown order.

This class mainly serves as base class for BeanFactory implementations, factoring out the common management of singleton bean instances. Note that the ConfigurableBeanFactory interface extends the SingletonBeanRegistry interface.

Note that this class assumes neither a bean definition concept nor a specific creation process for bean instances, in contrast to AbstractBeanFactory and DefaultListableBeanFactory (which inherit from it). Can alternatively also be used as a nested helper to delegate to.

Since:

2.0

Author:

Juergen Hoeller

See Also:

registerSingleton(java.lang.String, java.lang.Object), registerDisposableBean(java.lang.String, org.springframework.beans.factory.DisposableBean), DisposableBean, ConfigurableBeanFactory

Field Summary

protected Log	logger Logger available to subclasses
protected static Object	NULL_OBJECT Internal marker for a null singleton object: used as marker value for concurrent Maps (which don't support null values).

Constructor Summary

DefaultSingletonBeanRegistry()

Method Summary

protected void	addSingleton(String beanName, Object singletonObject) Add the given singleton object to the singleton cache of this factory.
protected void	addSingletonFactory(String beanName, ObjectFactory singletonFactory) Add the given singleton factory for building the specified singleton if necessary.
protected void	afterSingletonCreation(String beanName) Callback after singleton creation.
protected void	beforeSingletonCreation(String beanName) Callback before singleton creation.
boolean	containsSingleton(String beanName) Check if this registry contains a singleton instance with the given name.
protected void	destroyBean(String beanName, DisposableBean bean) Destroy the given bean.
void	destroySingleton(String beanName) Destroy the given bean.
void	destroySingletons()
String[]	getDependenciesForBean(String beanName) Return the names of all beans that the specified bean depends on, if any.
String[]	getDependentBeans(String beanName) Return the names of all beans which depend on the specified bean, if any.
Object	getSingleton(String beanName) Return the (raw) singleton object registered under the given name.
protected Object	getSingleton(String beanName, boolean allowEarlyReference) Return the (raw) singleton object registered under the given name.
Object	getSingleton(String beanName, ObjectFactory singletonFactory) Return the (raw) singleton object registered under the given name, creating and registering a new one if none registered yet.
int	getSingletonCount() Return the number of singleton beans registered in this registry.
protected Object	getSingletonMutex() Expose the singleton mutex to subclasses.
String[]	getSingletonNames() Return the names of singleton beans registered in this registry.
protected boolean	hasDependentBean(String beanName) Determine whether a dependent bean has been registered for the given name.
boolean	isSingletonCurrentlyInCreation(String beanName) Return whether the specified singleton bean is currently in creation (within the entire factory).
protected void	onSuppressedException(Exception ex) Register an Exception that happened to get suppressed during the creation of a singleton bean instance, e.g.
void	registerContainedBean(String containedBeanName, String containingBeanName) Register a containment relationship between two beans, e.g.
void	registerDependentBean(String beanName, String dependentBeanName) Register a dependent bean for the given bean, to be destroyed before the given bean is destroyed.
void	registerDisposableBean(String beanName, DisposableBean bean) Add the given bean to the list of disposable beans in this registry.
void	registerSingleton(String beanName, Object singletonObject) Register the given existing object as singleton in the bean registry, under the given bean name.
protected void	removeSingleton(String beanName) Remove the bean with the given name from the singleton cache of this factory, to be able to clean up eager registration of a singleton if creation failed.
void	setCurrentlyInCreation(String beanName, boolean inCreation)

Methods inherited from class org.springframework.core.SimpleAliasRegistry

allowAliasOverriding, canonicalName, checkForAliasCircle, getAliases, isAlias, registerAlias, removeAlias, resolveAliases

Methods inherited from class java.lang.Object

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

Field Detail

NULL_OBJECT

protected static final Object NULL_OBJECT

Internal marker for a null singleton object: used as marker value for concurrent Maps (which don't support null values).

logger

protected final Log logger

Logger available to subclasses

Constructor Detail

DefaultSingletonBeanRegistry

public DefaultSingletonBeanRegistry()

Method Detail

registerSingleton

public void registerSingleton(String beanName,
                              Object singletonObject)
                       throws IllegalStateException

Description copied from interface: SingletonBeanRegistry

Register the given existing object as singleton in the bean registry, under the given bean name.

The given instance is supposed to be fully initialized; the registry will not perform any initialization callbacks (in particular, it won't call InitializingBean's afterPropertiesSet method). The given instance will not receive any destruction callbacks (like DisposableBean's destroy method) either.

When running within a full BeanFactory: Register a bean definition instead of an existing instance if your bean is supposed to receive initialization and/or destruction callbacks.

Typically invoked during registry configuration, but can also be used for runtime registration of singletons. As a consequence, a registry implementation should synchronize singleton access; it will have to do this anyway if it supports a BeanFactory's lazy initialization of singletons.

Specified by:

registerSingleton in interface SingletonBeanRegistry

Parameters:

beanName - the name of the bean

singletonObject - the existing singleton object

Throws:

IllegalStateException

See Also:

InitializingBean.afterPropertiesSet(), DisposableBean.destroy(), BeanDefinitionRegistry.registerBeanDefinition(java.lang.String, org.springframework.beans.factory.config.BeanDefinition)

addSingleton

protected void addSingleton(String beanName,
                            Object singletonObject)

Add the given singleton object to the singleton cache of this factory.

To be called for eager registration of singletons.

Parameters:

beanName - the name of the bean

singletonObject - the singleton object

addSingletonFactory

protected void addSingletonFactory(String beanName,
                                   ObjectFactory singletonFactory)

Add the given singleton factory for building the specified singleton if necessary.

To be called for eager registration of singletons, e.g. to be able to resolve circular references.

Parameters:

beanName - the name of the bean

singletonFactory - the factory for the singleton object

getSingleton

public Object getSingleton(String beanName)

Description copied from interface: SingletonBeanRegistry

Return the (raw) singleton object registered under the given name.

Only checks already instantiated singletons; does not return an Object for singleton bean definitions which have not been instantiated yet.

The main purpose of this method is to access manually registered singletons (see SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object)). Can also be used to access a singleton defined by a bean definition that already been created, in a raw fashion.

NOTE: This lookup method is not aware of FactoryBean prefixes or aliases. You need to resolve the canonical bean name first before obtaining the singleton instance.

Specified by:

getSingleton in interface SingletonBeanRegistry

Parameters:

beanName - the name of the bean to look for

Returns:

the registered singleton object, or null if none found

See Also:

ConfigurableListableBeanFactory.getBeanDefinition(java.lang.String)

getSingleton

protected Object getSingleton(String beanName,
                              boolean allowEarlyReference)

Return the (raw) singleton object registered under the given name.

Checks already instantiated singletons and also allows for an early reference to a currently created singleton (resolving a circular reference).

Parameters:

beanName - the name of the bean to look for

allowEarlyReference - whether early references should be created or not

Returns:

the registered singleton object, or null if none found

getSingleton

public Object getSingleton(String beanName,
                           ObjectFactory singletonFactory)

Return the (raw) singleton object registered under the given name, creating and registering a new one if none registered yet.

Parameters:

beanName - the name of the bean

singletonFactory - the ObjectFactory to lazily create the singleton with, if necessary

Returns:

the registered singleton object

onSuppressedException

protected void onSuppressedException(Exception ex)

Register an Exception that happened to get suppressed during the creation of a singleton bean instance, e.g. a temporary circular reference resolution problem.

Parameters:

ex - the Exception to register

removeSingleton

protected void removeSingleton(String beanName)

Remove the bean with the given name from the singleton cache of this factory, to be able to clean up eager registration of a singleton if creation failed.

Parameters:

beanName - the name of the bean

See Also:

getSingletonMutex()

containsSingleton

public boolean containsSingleton(String beanName)

Description copied from interface: SingletonBeanRegistry

Check if this registry contains a singleton instance with the given name.

Only checks already instantiated singletons; does not return true for singleton bean definitions which have not been instantiated yet.

The main purpose of this method is to check manually registered singletons (see SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object)). Can also be used to check whether a singleton defined by a bean definition has already been created.

To check whether a bean factory contains a bean definition with a given name, use ListableBeanFactory's containsBeanDefinition. Calling both containsBeanDefinition and containsSingleton answers whether a specific bean factory contains a local bean instance with the given name.

Use BeanFactory's containsBean for general checks whether the factory knows about a bean with a given name (whether manually registered singleton instance or created by bean definition), also checking ancestor factories.

NOTE: This lookup method is not aware of FactoryBean prefixes or aliases. You need to resolve the canonical bean name first before checking the singleton status.

Specified by:

containsSingleton in interface SingletonBeanRegistry

Parameters:

beanName - the name of the bean to look for

Returns:

if this bean factory contains a singleton instance with the given name

See Also:

SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object), ListableBeanFactory.containsBeanDefinition(java.lang.String), BeanFactory.containsBean(java.lang.String)

getSingletonNames

public String[] getSingletonNames()

Description copied from interface: SingletonBeanRegistry

Return the names of singleton beans registered in this registry.

Only checks already instantiated singletons; does not return names for singleton bean definitions which have not been instantiated yet.

The main purpose of this method is to check manually registered singletons (see SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object)). Can also be used to check which singletons defined by a bean definition have already been created.

Specified by:

getSingletonNames in interface SingletonBeanRegistry

Returns:

the list of names as a String array (never null)

See Also:

SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object), BeanDefinitionRegistry.getBeanDefinitionNames(), ListableBeanFactory.getBeanDefinitionNames()

getSingletonCount

public int getSingletonCount()

Description copied from interface: SingletonBeanRegistry

Return the number of singleton beans registered in this registry.

Only checks already instantiated singletons; does not count singleton bean definitions which have not been instantiated yet.

The main purpose of this method is to check manually registered singletons (see SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object)). Can also be used to count the number of singletons defined by a bean definition that have already been created.

Specified by:

getSingletonCount in interface SingletonBeanRegistry

Returns:

the number of singleton beans

See Also:

SingletonBeanRegistry.registerSingleton(java.lang.String, java.lang.Object), BeanDefinitionRegistry.getBeanDefinitionCount(), ListableBeanFactory.getBeanDefinitionCount()

beforeSingletonCreation

protected void beforeSingletonCreation(String beanName)

Callback before singleton creation.

Default implementation register the singleton as currently in creation.

Parameters:

beanName - the name of the singleton about to be created

See Also:

isSingletonCurrentlyInCreation(java.lang.String)

afterSingletonCreation

protected void afterSingletonCreation(String beanName)

Callback after singleton creation.

Default implementation marks the singleton as not in creation anymore.

Parameters:

beanName - the name of the singleton that has been created

See Also:

isSingletonCurrentlyInCreation(java.lang.String)

setCurrentlyInCreation

public final void setCurrentlyInCreation(String beanName,
                                         boolean inCreation)

isSingletonCurrentlyInCreation

public final boolean isSingletonCurrentlyInCreation(String beanName)

Return whether the specified singleton bean is currently in creation (within the entire factory).

Parameters:

beanName - the name of the bean

registerDisposableBean

public void registerDisposableBean(String beanName,
                                   DisposableBean bean)

Add the given bean to the list of disposable beans in this registry. Disposable beans usually correspond to registered singletons, matching the bean name but potentially being a different instance (for example, a DisposableBean adapter for a singleton that does not naturally implement Spring's DisposableBean interface).

Parameters:

beanName - the name of the bean

bean - the bean instance

registerContainedBean

public void registerContainedBean(String containedBeanName,
                                  String containingBeanName)

Register a containment relationship between two beans, e.g. between an inner bean and its containing outer bean.

Also registers the containing bean as dependent on the contained bean in terms of destruction order.

Parameters:

containedBeanName - the name of the contained (inner) bean

containingBeanName - the name of the containing (outer) bean

See Also:

registerDependentBean(java.lang.String, java.lang.String)

registerDependentBean

public void registerDependentBean(String beanName,
                                  String dependentBeanName)

Register a dependent bean for the given bean, to be destroyed before the given bean is destroyed.

Parameters:

beanName - the name of the bean

dependentBeanName - the name of the dependent bean

hasDependentBean

protected boolean hasDependentBean(String beanName)

Determine whether a dependent bean has been registered for the given name.

Parameters:

beanName - the name of the bean to check

getDependentBeans

public String[] getDependentBeans(String beanName)

Return the names of all beans which depend on the specified bean, if any.

Parameters:

beanName - the name of the bean

Returns:

the array of dependent bean names, or an empty array if none

getDependenciesForBean

public String[] getDependenciesForBean(String beanName)

Return the names of all beans that the specified bean depends on, if any.

Parameters:

beanName - the name of the bean

Returns:

the array of names of beans which the bean depends on, or an empty array if none

destroySingletons

public void destroySingletons()

destroySingleton

public void destroySingleton(String beanName)

Destroy the given bean. Delegates to destroyBean if a corresponding disposable bean instance is found.

Parameters:

beanName - the name of the bean

See Also:

destroyBean(java.lang.String, org.springframework.beans.factory.DisposableBean)

destroyBean

protected void destroyBean(String beanName,
                           DisposableBean bean)

Destroy the given bean. Must destroy beans that depend on the given bean before the bean itself. Should not throw any exceptions.

Parameters:

beanName - the name of the bean

bean - the bean instance to destroy

getSingletonMutex

protected final Object getSingletonMutex()

Expose the singleton mutex to subclasses.

Subclasses should synchronize on the given Object if they perform any sort of extended singleton creation phase. In particular, subclasses should not have their own mutexes involved in singleton creation, to avoid the potential for deadlocks in lazy-init situations.