The Spring Framework

## org.springframework.beans.factory
Interface BeanFactory

All Known Subinterfaces:
  ApplicationContext, AutowireCapableBeanFactory, ConfigurableApplicationContext, ConfigurableBeanFactory, ConfigurableListableBeanFactory, ConfigurablePortletApplicationContext, ConfigurableWebApplicationContext, HierarchicalBeanFactory, ListableBeanFactory, WebApplicationContext

All Known Implementing Classes:
  AbstractApplicationContext, AbstractAutowireCapableBeanFactory, AbstractBeanFactory, AbstractRefreshableApplicationContext, AbstractRefreshableConfigApplicationContext, AbstractRefreshablePortletApplicationContext, AbstractRefreshableWebApplicationContext, AbstractXmlApplicationContext, ClassPathXmlApplicationContext, DefaultListableBeanFactory, FileSystemXmlApplicationContext, GenericApplicationContext, GenericWebApplicationContext, ResourceAdapterApplicationContext, SimpleJndiBeanFactory, StaticApplicationContext, StaticListableBeanFactory, StaticPortletApplicationContext, StaticWebApplicationContext, XmlBeanFactory, XmlPortletApplicationContext, 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 (e.g. "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. ResourceLoaderAware's `setResourceLoader` (only applicable when running in an application context)
5. ApplicationEventPublisherAware's `setApplicationEventPublisher` (only applicable when running in an application context)
6. MessageSourceAware's `setMessageSource` (only applicable when running in an application context)
7. ApplicationContextAware's `setApplicationContext` (only applicable when running in an application context)
8. ServletContextAware's `setServletContext` (only applicable when running in a web application context)
9. `postProcessBeforeInitialization` methods of BeanPostProcessors
10. InitializingBean's `afterPropertiesSet`
11. a custom init-method definition
12. `postProcessAfterInitialization` methods of BeanPostProcessors

On shutdown of a bean factory, the following lifecycle methods apply:
1. DisposableBean's `destroy`
2. a custom destroy-method definition

Since:
  13 April 2001
Author:
  Rod Johnson, Juergen Hoeller
See Also:
  `BeanNameAware.setBeanName(java.lang.String)`, `BeanClassLoaderAware.setBeanClassLoader(java.lang.ClassLoader)`, `BeanFactoryAware.setBeanFactory(org.springframework.beans.factory.BeanFactory)`, `ResourceLoaderAware.setResourceLoader(org.springframework.core.io.ResourceLoader)`, `ApplicationEventPublisherAware.setApplicationEventPublisher(org.springframework.context.ApplicationEventPublisher)`, `MessageSourceAware.setMessageSource(org.springframework.context.MessageSource)`, `ApplicationContextAware.setApplicationContext(org.springframework.context.ApplicationContext)`, `ServletContextAware.setServletContext(javax.servlet.ServletContext)`, `BeanPostProcessor.postProcessBeforeInitialization(java.lang.Object, java.lang.String)`, `InitializingBean.afterPropertiesSet()`, `AbstractBeanDefinition.getInitMethodName()`, `BeanPostProcessor.postProcessAfterInitialization(java.lang.Object, java.lang.String)`, `DisposableBean.destroy()`, `AbstractBeanDefinition.getDestroyMethodName()`

Field Summary
`static String` `FACTORY_BEAN_PREFIX` Used to dereference a `FactoryBean` instance and distinguish it from beans created by the FactoryBean.

Method Summary
`boolean` `containsBean(String name)` Does this bean factory contain a bean with the given name?
`String[]` `getAliases(String name)` Return the aliases for the given bean name, if any.
`Object` `getBean(String name)` Return an instance, which may be shared or independent, of the specified bean.
`Object` `getBean(String name, Class requiredType)` Return an instance, which may be shared or independent, of the specified bean.
`Object` `getBean(String name, Object[] args)` Return an instance, which may be shared or independent, of the specified bean.
`Class` `getType(String name)` Determine the type of the bean with the given name.
`boolean` `isPrototype(String name)` Is this bean a prototype?
`boolean` `isSingleton(String name)` Is this bean a shared singleton?
`boolean` `isTypeMatch(String name, Class targetType)` Check whether the bean with the given name matches the specified type.

Field Detail

### 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:
    Constant Field Values

Method Detail

### 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
  Throws:
    `NoSuchBeanDefinitionException` - if there is no bean definition with the specified name
    `BeansException` - if the bean could not be obtained

### getBean

    Object getBean(String name,
                   Class 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 of the actual class, or `null` for any match. For example, if the value is `Object.class`, this method will succeed whatever the class of the returned instance.
  Returns:
    an instance of the bean
  Throws:
    `NoSuchBeanDefinitionException` - if there's 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,
                   Object[] 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.

  Parameters:
    `name` - the name of the bean to retrieve
    `args` - arguments to use if creating a prototype using explicit arguments to a static factory method. It is invalid to use a non-null args value in any other case.
  Returns:
    an instance of the bean
  Throws:
    `NoSuchBeanDefinitionException` - if there's 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

### containsBean

    boolean containsBean(String name)

  Does this bean factory contain a bean with the given name? More specifically, is `getBean(java.lang.String)` able to obtain a bean instance for the given name?

  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 a bean with the given name is defined

### 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:
    `getBean(java.lang.String)`, `isPrototype(java.lang.String)`

### 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:
    `getBean(java.lang.String)`, `isSingleton(java.lang.String)`

### isTypeMatch

    boolean isTypeMatch(String name,
                        Class targetType)
                        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
    `targetType` - the type to match against
  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:
    `getBean(java.lang.String)`, `getType(java.lang.String)`

### getType

    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()`.

  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:
    `getBean(java.lang.String)`, `isTypeMatch(java.lang.String, java.lang.Class)`

### 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:
    `getBean(java.lang.String)`

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