Package org.springframework.beans.factory

Interface BeanFactory

All Known Subinterfaces:
ApplicationContext, AutowireCapableBeanFactory, ConfigurableApplicationContext, ConfigurableBeanFactory, ConfigurableListableBeanFactory, ConfigurableWebApplicationContext, HierarchicalBeanFactory, ListableBeanFactory, WebApplicationContext
All Known Implementing Classes:
AbstractApplicationContext, AbstractAutowireCapableBeanFactory, AbstractBeanFactory, AbstractRefreshableApplicationContext, AbstractRefreshableConfigApplicationContext, AbstractRefreshableWebApplicationContext, AbstractXmlApplicationContext, AnnotationConfigApplicationContext, AnnotationConfigWebApplicationContext, ClassPathXmlApplicationContext, DefaultListableBeanFactory, FileSystemXmlApplicationContext, GenericApplicationContext, GenericGroovyApplicationContext, GenericWebApplicationContext, GenericXmlApplicationContext, GroovyWebApplicationContext, SimpleJndiBeanFactory, StaticApplicationContext, StaticListableBeanFactory, StaticWebApplicationContext, XmlWebApplicationContext
public interface BeanFactory
The root interface for accessing a Spring bean container.

This is the basic client view of a bean container; further interfaces such as ListableBeanFactory and ConfigurableBeanFactory are available for specific purposes.

This interface is implemented by objects that hold a number of bean definitions, each uniquely identified by a String name. Depending on the bean definition, the factory will return either an independent instance of a contained object (the Prototype design pattern), or a single shared instance (a superior alternative to the Singleton design pattern, in which the instance is a singleton in the scope of the factory). Which type of instance will be returned depends on the bean factory configuration: the API is the same. Since Spring 2.0, further scopes are available depending on the concrete application context (for example, "request" and "session" scopes in a web environment).

The point of this approach is that the BeanFactory is a central registry of application components, and centralizes configuration of application components (no more do individual objects need to read properties files, for example). See chapters 4 and 11 of "Expert One-on-One J2EE Design and Development" for a discussion of the benefits of this approach.

Note that it is generally better to rely on Dependency Injection ("push" configuration) to configure application objects through setters or constructors, rather than use any form of "pull" configuration like a BeanFactory lookup. Spring's Dependency Injection functionality is implemented using this BeanFactory interface and its subinterfaces.

Normally a BeanFactory will load bean definitions stored in a configuration source (such as an XML document), and use the org.springframework.beans package to configure the beans. However, an implementation could simply return Java objects it creates as necessary directly in Java code. There are no constraints on how the definitions could be stored: LDAP, RDBMS, XML, properties file, etc. Implementations are encouraged to support references amongst beans (Dependency Injection).

In contrast to the methods in ListableBeanFactory, all of the operations in this interface will also check parent factories if this is a HierarchicalBeanFactory. If a bean is not found in this factory instance, the immediate parent factory will be asked. Beans in this factory instance are supposed to override beans of the same name in any parent factory.

Bean factory implementations should support the standard bean lifecycle interfaces as far as possible. The full set of initialization methods and their standard order is:

  1. BeanNameAware's setBeanName
  2. BeanClassLoaderAware's setBeanClassLoader
  3. BeanFactoryAware's setBeanFactory
  4. EnvironmentAware's setEnvironment
  5. EmbeddedValueResolverAware's setEmbeddedValueResolver
  6. ResourceLoaderAware's setResourceLoader (only applicable when running in an application context)
  7. ApplicationEventPublisherAware's setApplicationEventPublisher (only applicable when running in an application context)
  8. MessageSourceAware's setMessageSource (only applicable when running in an application context)
  9. ApplicationContextAware's setApplicationContext (only applicable when running in an application context)
  10. ServletContextAware's setServletContext (only applicable when running in a web application context)
  11. postProcessBeforeInitialization methods of BeanPostProcessors
  12. InitializingBean's afterPropertiesSet
  13. a custom init-method definition
  14. postProcessAfterInitialization methods of BeanPostProcessors

On shutdown of a bean factory, the following lifecycle methods apply:

  1. postProcessBeforeDestruction methods of DestructionAwareBeanPostProcessors
  2. DisposableBean's destroy
  3. a custom destroy-method definition
Since:
13 April 2001
Author:
Rod Johnson, Juergen Hoeller, Chris Beams
See Also:

  • Field Details

    • FACTORY_BEAN_PREFIX

      static final String FACTORY_BEAN_PREFIX
      Used to dereference a FactoryBean instance and distinguish it from beans created by the FactoryBean. For example, if the bean named myJndiObject is a FactoryBean, getting &myJndiObject will return the factory, not the instance returned by the factory.
      See Also:

  • Method Details

    • getBean

      Object getBean(String name) throws BeansException
      Return an instance, which may be shared or independent, of the specified bean.

      This method allows a Spring BeanFactory to be used as a replacement for the Singleton or Prototype design pattern. Callers may retain references to returned objects in the case of Singleton beans.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to retrieve
      Returns:
      an instance of the bean. Note that the return value will never be null but possibly a stub for null returned from a factory method, to be checked via equals(null). Consider using getBeanProvider(Class) for resolving optional dependencies.
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the specified name
      BeansException - if the bean could not be obtained

    • getBean

      <T> T getBean(String name, Class<T> requiredType) throws BeansException
      Return an instance, which may be shared or independent, of the specified bean.

      Behaves the same as getBean(String), but provides a measure of type safety by throwing a BeanNotOfRequiredTypeException if the bean is not of the required type. This means that ClassCastException can't be thrown on casting the result correctly, as can happen with getBean(String).

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to retrieve
      requiredType - type the bean must match; can be an interface or superclass
      Returns:
      an instance of the bean. Note that the return value will never be null. In case of a stub for null from a factory method having been resolved for the requested bean, a BeanNotOfRequiredTypeException against the NullBean stub will be raised. Consider using getBeanProvider(Class) for resolving optional dependencies.
      Throws:
      NoSuchBeanDefinitionException - if there is no such bean definition
      BeanNotOfRequiredTypeException - if the bean is not of the required type
      BeansException - if the bean could not be created

    • getBean

      Object getBean(String name, @Nullable Object @Nullable ... args) throws BeansException
      Return an instance, which may be shared or independent, of the specified bean.

      Allows for specifying explicit constructor arguments / factory method arguments, overriding the specified default arguments (if any) in the bean definition. Note that the provided arguments need to match a specific candidate constructor / factory method in the order of declared parameters.

      Parameters:
      name - the name of the bean to retrieve
      args - arguments to use when creating a bean instance using explicit arguments (only applied when creating a new instance as opposed to retrieving an existing one)
      Returns:
      an instance of the bean
      Throws:
      NoSuchBeanDefinitionException - if there is no such bean definition
      BeanDefinitionStoreException - if arguments have been given but the affected bean isn't a prototype
      BeansException - if the bean could not be created
      Since:
      2.5

    • getBean

      <T> T getBean(Class<T> requiredType) throws BeansException
      Return the bean instance that uniquely matches the given object type, if any.

      This method goes into ListableBeanFactory by-type lookup territory but may also be translated into a conventional by-name lookup based on the name of the given type. For more extensive retrieval operations across sets of beans, use ListableBeanFactory and/or BeanFactoryUtils.

      Parameters:
      requiredType - type the bean must match; can be an interface or superclass
      Returns:
      an instance of the single bean matching the required type
      Throws:
      NoSuchBeanDefinitionException - if no bean of the given type was found
      NoUniqueBeanDefinitionException - if more than one bean of the given type was found
      BeansException - if the bean could not be created
      Since:
      3.0
      See Also:

    • getBean

      <T> T getBean(Class<T> requiredType, @Nullable Object @Nullable ... args) throws BeansException
      Return an instance, which may be shared or independent, of the specified bean.

      Allows for specifying explicit constructor arguments / factory method arguments, overriding the specified default arguments (if any) in the bean definition. Note that the provided arguments need to match a specific candidate constructor / factory method in the order of declared parameters.

      This method goes into ListableBeanFactory by-type lookup territory but may also be translated into a conventional by-name lookup based on the name of the given type. For more extensive retrieval operations across sets of beans, use ListableBeanFactory and/or BeanFactoryUtils.

      Parameters:
      requiredType - type the bean must match; can be an interface or superclass
      args - arguments to use when creating a bean instance using explicit arguments (only applied when creating a new instance as opposed to retrieving an existing one)
      Returns:
      an instance of the bean
      Throws:
      NoSuchBeanDefinitionException - if there is no such bean definition
      BeanDefinitionStoreException - if arguments have been given but the affected bean isn't a prototype
      BeansException - if the bean could not be created
      Since:
      4.1

    • getBeanProvider

      <T> ObjectProvider<T> getBeanProvider(Class<T> requiredType)
      Return a provider for the specified bean, allowing for lazy on-demand retrieval of instances, including availability and uniqueness options.

      For matching a generic type, consider getBeanProvider(ResolvableType).

      Parameters:
      requiredType - type the bean must match; can be an interface or superclass
      Returns:
      a corresponding provider handle
      Since:
      5.1
      See Also:

    • getBeanProvider

      <T> ObjectProvider<T> getBeanProvider(ResolvableType requiredType)
      Return a provider for the specified bean, allowing for lazy on-demand retrieval of instances, including availability and uniqueness options. This variant allows for specifying a generic type to match, similar to reflective injection points with generic type declarations in method/constructor parameters.

      Note that collections of beans are not supported here, in contrast to reflective injection points. For programmatically retrieving a list of beans matching a specific type, specify the actual bean type as an argument here and subsequently use ObjectProvider.orderedStream() or its lazy streaming/iteration options.

      Also, generics matching is strict here, as per the Java assignment rules. For lenient fallback matching with unchecked semantics (similar to the 'unchecked' Java compiler warning), consider calling getBeanProvider(Class) with the raw type as a second step if no full generic match is available with this variant.

      Parameters:
      requiredType - type the bean must match; can be a generic type declaration
      Returns:
      a corresponding provider handle
      Since:
      5.1
      See Also:

    • containsBean

      boolean containsBean(String name)
      Does this bean factory contain a bean definition or externally registered singleton instance with the given name?

      If the given name is an alias, it will be translated back to the corresponding canonical bean name.

      If this factory is hierarchical, will ask any parent factory if the bean cannot be found in this factory instance.

      If a bean definition or singleton instance matching the given name is found, this method will return true whether the named bean definition is concrete or abstract, lazy or eager, in scope or not. Therefore, note that a true return value from this method does not necessarily indicate that getBean(java.lang.String) will be able to obtain an instance for the same name.

      Parameters:
      name - the name of the bean to query
      Returns:
      whether a bean with the given name is present

    • isSingleton

      boolean isSingleton(String name) throws NoSuchBeanDefinitionException
      Is this bean a shared singleton? That is, will getBean(java.lang.String) always return the same instance?

      Note: This method returning false does not clearly indicate independent instances. It indicates non-singleton instances, which may correspond to a scoped bean as well. Use the isPrototype(java.lang.String) operation to explicitly check for independent instances.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      Returns:
      whether this bean corresponds to a singleton instance
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      See Also:

    • isPrototype

      boolean isPrototype(String name) throws NoSuchBeanDefinitionException
      Is this bean a prototype? That is, will getBean(java.lang.String) always return independent instances?

      Note: This method returning false does not clearly indicate a singleton object. It indicates non-independent instances, which may correspond to a scoped bean as well. Use the isSingleton(java.lang.String) operation to explicitly check for a shared singleton instance.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      Returns:
      whether this bean will always deliver independent instances
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      Since:
      2.0.3
      See Also:

    • isTypeMatch

      boolean isTypeMatch(String name, ResolvableType typeToMatch) throws NoSuchBeanDefinitionException
      Check whether the bean with the given name matches the specified type. More specifically, check whether a getBean(java.lang.String) call for the given name would return an object that is assignable to the specified target type.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      typeToMatch - the type to match against (as a ResolvableType)
      Returns:
      true if the bean type matches, false if it doesn't match or cannot be determined yet
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      Since:
      4.2
      See Also:

    • isTypeMatch

      boolean isTypeMatch(String name, Class<?> typeToMatch) throws NoSuchBeanDefinitionException
      Check whether the bean with the given name matches the specified type. More specifically, check whether a getBean(java.lang.String) call for the given name would return an object that is assignable to the specified target type.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      typeToMatch - the type to match against (as a Class)
      Returns:
      true if the bean type matches, false if it doesn't match or cannot be determined yet
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      Since:
      2.0.1
      See Also:

    • getType

      @Nullable Class<?> getType(String name) throws NoSuchBeanDefinitionException
      Determine the type of the bean with the given name. More specifically, determine the type of object that getBean(java.lang.String) would return for the given name.

      For a FactoryBean, return the type of object that the FactoryBean creates, as exposed by FactoryBean.getObjectType(). This may lead to the initialization of a previously uninitialized FactoryBean (see getType(String, boolean)).

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      Returns:
      the type of the bean, or null if not determinable
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      Since:
      1.1.2
      See Also:

    • getType

      @Nullable Class<?> getType(String name, boolean allowFactoryBeanInit) throws NoSuchBeanDefinitionException
      Determine the type of the bean with the given name. More specifically, determine the type of object that getBean(java.lang.String) would return for the given name.

      For a FactoryBean, return the type of object that the FactoryBean creates, as exposed by FactoryBean.getObjectType(). Depending on the allowFactoryBeanInit flag, this may lead to the initialization of a previously uninitialized FactoryBean if no early type information is available.

      Translates aliases back to the corresponding canonical bean name.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the name of the bean to query
      allowFactoryBeanInit - whether a FactoryBean may get initialized just for the purpose of determining its object type
      Returns:
      the type of the bean, or null if not determinable
      Throws:
      NoSuchBeanDefinitionException - if there is no bean with the given name
      Since:
      5.2
      See Also:

    • getAliases

      String[] getAliases(String name)
      Return the aliases for the given bean name, if any.

      All of those aliases point to the same bean when used in a getBean(java.lang.String) call.

      If the given name is an alias, the corresponding original bean name and other aliases (if any) will be returned, with the original bean name being the first element in the array.

      Will ask the parent factory if the bean cannot be found in this factory instance.

      Parameters:
      name - the bean name to check for aliases
      Returns:
      the aliases, or an empty array if none
      See Also: