BeanFactory (Spring Framework API 2.0)

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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, AbstractRefreshablePortletApplicationContext, AbstractRefreshableWebApplicationContext, AbstractXmlApplicationContext, ClassPathXmlApplicationContext, DefaultListableBeanFactory, FileSystemXmlApplicationContext, GenericApplicationContext, GenericWebApplicationContext, 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.
`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.