org.springframework.beans.factory
Interface BeanFactory

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

public interface BeanFactory

Interface to be implemented by objects that hold a number of bean definitions, each uniquely identified by a String name. An independent instance of any of these objects can be obtained (the Prototype design pattern), or a single shared instance can be obtained (a superior alternative to the Singleton design pattern). Which type of instance will be returned depends on the bean factory configuration - the API is the same. The Singleton approach is much more useful and more common in practice.

The point of this approach is that the BeanFactory is a central registry of application components, and centralizes the configuring 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.

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, to either Singletons or Prototypes.

In contrast to the methods in ListableBeanFactory, all of the methods 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 is asked. Beans in this factory instance are supposed to override beans of the same name in any parent factory.

Bean factories are supposed to support the standard bean lifecycle interfaces as far as possible. The maximum set of initialization methods and their standard order is:
1. BeanNameAware's setBeanName
2. BeanFactoryAware's setBeanFactory
3. ApplicationContextAware's setApplicationContext (only applicable if running in an application context)
4. postProcessBeforeInitialization methods of BeanPostProcessors
5. InitializingBean's afterPropertiesSet
6. a custom init-method definition
7. 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

Author:: Rod Johnson, Juergen Hoeller
Version: $Revision: 1.6 $
Since: 13 April 2001
See Also: BeanNameAware.setBeanName(java.lang.String), BeanFactoryAware.setBeanFactory(org.springframework.beans.factory.BeanFactory), InitializingBean.afterPropertiesSet(), DisposableBean.destroy(), org.springframework.beans.factory.config.BeanPostProcessor.postProcessBeforeInitialization(java.lang.Object,java.lang.String), org.springframework.beans.factory.config.BeanPostProcessor.postProcessAfterInitialization(java.lang.Object,java.lang.String), org.springframework.beans.factory.support.RootBeanDefinition.getInitMethodName(), org.springframework.beans.factory.support.RootBeanDefinition.getDestroyMethodName(), org.springframework.context.ApplicationContextAware.setApplicationContext(org.springframework.context.ApplicationContext)

Method Summary
`boolean`	`containsBean(String name)` Does this bean factory contain a bean with the given name? Will ask the parent factory if the bean cannot be found in this factory instance.
`String[]`	`getAliases(String name)` Return the aliases for the given bean name, if defined.
`Object`	`getBean(String name)` Return an instance (possibly shared or independent) of the given bean name.
`Object`	`getBean(String name, Class requiredType)` Return an instance (possibly shared or independent) of the given bean name.
`boolean`	`isSingleton(String name)` Is this bean a singleton? That is, will getBean() always return the same object? Will ask the parent factory if the bean cannot be found in this factory instance.

Method Detail