Package 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:

  • Constructor Details

    • DefaultSingletonBeanRegistry

      public DefaultSingletonBeanRegistry()

  • Method Details

    • 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:

    • addSingleton

      protected void addSingleton(String beanName, Object singletonObject)
      Add the given singleton object to the singleton registry.

      To be called for exposure of freshly registered/created 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 early exposure purposes, for example, to be able to resolve circular references.

      Parameters:
      beanName - the name of the bean
      singletonFactory - the factory for the singleton object

    • addSingletonCallback

      public void addSingletonCallback(String beanName, Consumer<Object> singletonConsumer)
      Description copied from interface: SingletonBeanRegistry
      Add a callback to be triggered when the specified singleton becomes available in the bean registry.
      Specified by:
      addSingletonCallback in interface SingletonBeanRegistry
      Parameters:
      beanName - the name of the bean
      singletonConsumer - a callback for reacting to the availability of the freshly registered/created singleton instance (intended for follow-up steps before the bean is actively used by other callers, not for modifying the given singleton instance itself)

    • getSingleton

      @Nullable 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:

    • getSingleton

      @Nullable 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

    • isCurrentThreadAllowedToHoldSingletonLock

      @Nullable protected Boolean isCurrentThreadAllowedToHoldSingletonLock()
      Determine whether the current thread is allowed to hold the singleton lock.

      By default, any thread may acquire and hold the singleton lock, except background threads from DefaultListableBeanFactory.setBootstrapExecutor(java.util.concurrent.Executor).

      Returns:
      false if the current thread is explicitly not allowed to hold the lock, true if it is explicitly allowed to hold the lock but also accepts lenient fallback behavior, or null if there is no specific indication (traditional behavior: always holding a full lock)
      Since:
      6.2

    • onSuppressedException

      protected void onSuppressedException(Exception ex)
      Register an exception that happened to get suppressed during the creation of a singleton bean instance, for example, a temporary circular reference resolution problem.

      The default implementation preserves any given exception in this registry's collection of suppressed exceptions, up to a limit of 100 exceptions, adding them as related causes to an eventual top-level BeanCreationException.

      Parameters:
      ex - the Exception to register
      See Also:

    • removeSingleton

      protected void removeSingleton(String beanName)
      Remove the bean with the given name from the singleton registry, either on regular destruction or on cleanup after early exposure when creation failed.
      Parameters:
      beanName - the name of the bean

    • 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:

    • 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:

    • 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:

    • setCurrentlyInCreation

      public void setCurrentlyInCreation(String beanName, boolean inCreation)

    • isCurrentlyInCreation

      public boolean isCurrentlyInCreation(String beanName)

    • isActuallyInCreation

      protected boolean isActuallyInCreation(String beanName)

    • isSingletonCurrentlyInCreation

      public boolean isSingletonCurrentlyInCreation(@Nullable String beanName)
      Return whether the specified singleton bean is currently in creation (within the entire factory).
      Parameters:
      beanName - the name of the bean

    • beforeSingletonCreation

      protected void beforeSingletonCreation(String beanName)
      Callback before singleton creation.

      The default implementation register the singleton as currently in creation.

      Parameters:
      beanName - the name of the singleton about to be created
      See Also:

    • afterSingletonCreation

      protected void afterSingletonCreation(String beanName)
      Callback after singleton creation.

      The default implementation marks the singleton as not in creation anymore.

      Parameters:
      beanName - the name of the singleton that has been created
      See Also:

    • 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, for example, 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

      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

    • isDependent

      protected boolean isDependent(String beanName, String dependentBeanName)
      Determine whether the specified dependent bean has been registered as dependent on the given bean or on any of its transitive dependencies.
      Parameters:
      beanName - the name of the bean to check
      dependentBeanName - the name of the dependent bean
      Since:
      4.0

    • 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()

    • clearSingletonCache

      protected void clearSingletonCache()
      Clear all cached singleton instances in this registry.
      Since:
      4.3.15

    • 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

      protected void destroyBean(String beanName, @Nullable 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

      @Deprecated(since="6.2") public final Object getSingletonMutex()
      Deprecated.
      Description copied from interface: SingletonBeanRegistry
      Return the singleton mutex used by this registry (for external collaborators).
      Specified by:
      getSingletonMutex in interface SingletonBeanRegistry
      Returns:
      the mutex object (never null)