public class

DefaultSingletonBeanRegistry

extends SimpleAliasRegistry
implements SingletonBeanRegistry
java.lang.Object
   ↳ org.springframework.core.SimpleAliasRegistry
     ↳ org.springframework.beans.factory.support.DefaultSingletonBeanRegistry
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

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.

Summary

Fields
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).
protected final Log logger Logger available to subclasses
Public Constructors
DefaultSingletonBeanRegistry()
Public Methods
boolean containsSingleton(String beanName)
Check if this registry contains a singleton instance with the given name.
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, ObjectFactory singletonFactory)
Return the (raw) singleton object registered under the given name, creating and registering a new one if none registered yet.
Object getSingleton(String beanName)
Return the (raw) singleton object registered under the given name.
int getSingletonCount()
Return the number of singleton beans registered in this registry.
String[] getSingletonNames()
Return the names of singleton beans registered in this registry.
final boolean isSingletonCurrentlyInCreation(String beanName)
Return whether the specified singleton bean is currently in creation (within the entire factory).
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 Methods
void addSingleton(String beanName, Object singletonObject)
Add the given singleton object to the singleton cache of this factory.
void addSingletonFactory(String beanName, ObjectFactory singletonFactory)
Add the given singleton factory for building the specified singleton if necessary.
void afterSingletonCreation(String beanName)
Callback after singleton creation.
void beforeSingletonCreation(String beanName)
Callback before singleton creation.
void destroyBean(String beanName, DisposableBean bean)
Destroy the given bean.
Object getSingleton(String beanName, boolean allowEarlyReference)
Return the (raw) singleton object registered under the given name.
final Object getSingletonMutex()
Expose the singleton mutex to subclasses.
boolean hasDependentBean(String beanName)
Determine whether a dependent bean has been registered for the given name.
void onSuppressedException(Exception ex)
Register an Exception that happened to get suppressed during the creation of a singleton bean instance, e.g.
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.
[Expand]
Inherited Methods
From class org.springframework.core.SimpleAliasRegistry
From class java.lang.Object
From interface org.springframework.beans.factory.config.SingletonBeanRegistry
From interface org.springframework.core.AliasRegistry

Fields

protected static final Object NULL_OBJECT

Also: SpringBeans

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

protected final Log logger

Also: SpringBeans

Logger available to subclasses

Public Constructors

public DefaultSingletonBeanRegistry ()

Also: SpringBeans

Public Methods

public boolean containsSingleton (String beanName)

Also: SpringBeans

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 registerSingleton(String, 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.

Parameters
beanName the name of the bean to look for
Returns
  • if this bean factory contains a singleton instance with the given name

public void destroySingleton (String beanName)

Also: SpringBeans

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

Parameters
beanName the name of the bean

public void destroySingletons ()

Also: SpringBeans

public String[] getDependenciesForBean (String beanName)

Also: SpringBeans

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

public String[] getDependentBeans (String beanName)

Also: SpringBeans

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

public Object getSingleton (String beanName, ObjectFactory singletonFactory)

Also: SpringBeans

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

public Object getSingleton (String beanName)

Also: SpringBeans

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 registerSingleton(String, 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.

Parameters
beanName the name of the bean to look for
Returns
  • the registered singleton object, or null if none found

public int getSingletonCount ()

Also: SpringBeans

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 registerSingleton(String, Object)). Can also be used to count the number of singletons defined by a bean definition that have already been created.

Returns
  • the number of singleton beans

public String[] getSingletonNames ()

Also: SpringBeans

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 registerSingleton(String, Object)). Can also be used to check which singletons defined by a bean definition have already been created.

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

public final boolean isSingletonCurrentlyInCreation (String beanName)

Also: SpringBeans

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

Parameters
beanName the name of the bean

public void registerContainedBean (String containedBeanName, String containingBeanName)

Also: SpringBeans

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

public void registerDependentBean (String beanName, String dependentBeanName)

Also: SpringBeans

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

public void registerDisposableBean (String beanName, DisposableBean bean)

Also: SpringBeans

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

public void registerSingleton (String beanName, Object singletonObject)

Also: SpringBeans

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.

Parameters
beanName the name of the bean
singletonObject the existing singleton object

Protected Methods

protected void addSingleton (String beanName, Object singletonObject)

Also: SpringBeans

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

protected void addSingletonFactory (String beanName, ObjectFactory singletonFactory)

Also: SpringBeans

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

protected void afterSingletonCreation (String beanName)

Also: SpringBeans

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

protected void beforeSingletonCreation (String beanName)

Also: SpringBeans

Callback before singleton creation.

Default implementation register the singleton as currently in creation.

Parameters
beanName the name of the singleton about to be created

protected void destroyBean (String beanName, DisposableBean bean)

Also: SpringBeans

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

protected Object getSingleton (String beanName, boolean allowEarlyReference)

Also: SpringBeans

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

protected final Object getSingletonMutex ()

Also: SpringBeans

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.

protected boolean hasDependentBean (String beanName)

Also: SpringBeans

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

Parameters
beanName the name of the bean to check

protected void onSuppressedException (Exception ex)

Also: SpringBeans

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

protected void removeSingleton (String beanName)

Also: SpringBeans

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