public interface BeanFactory
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. 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
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()| Modifier and Type | Field and Description |
|---|---|
static String |
FACTORY_BEAN_PREFIX
Used to dereference a
FactoryBean instance and distinguish it from
beans created by the FactoryBean. |
| Modifier and Type | Method and Description |
|---|---|
boolean |
containsBean(String name)
Does this bean factory contain a bean definition or externally registered singleton
instance with the given name?
|
String[] |
getAliases(String name)
Return the aliases for the given bean name, if any.
|
<T> T |
getBean(Class<T> requiredType)
Return the bean instance that uniquely matches the given object type, if any.
|
Object |
getBean(String name)
Return an instance, which may be shared or independent, of the specified bean.
|
<T> T |
getBean(String name,
Class<T> 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? That is, will
getBean(java.lang.String) always return
independent instances? |
boolean |
isSingleton(String name)
Is this bean a shared singleton? That is, will
getBean(java.lang.String) always
return the same instance? |
boolean |
isTypeMatch(String name,
Class<?> targetType)
Check whether the bean with the given name matches the specified type.
|
static final String FACTORY_BEAN_PREFIX
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.Object getBean(String name) throws BeansException
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.
name - the name of the bean to retrieveNoSuchBeanDefinitionException - if there is no bean definition
with the specified nameBeansException - if the bean could not be obtained<T> T getBean(String name, Class<T> requiredType) throws BeansException
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.
name - the name of the bean to retrieverequiredType - 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.NoSuchBeanDefinitionException - if there is no such bean definitionBeanNotOfRequiredTypeException - if the bean is not of the required typeBeansException - if the bean could not be created<T> T getBean(Class<T> requiredType) throws BeansException
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.
requiredType - type the bean must match; can be an interface or superclass.
null is disallowed.NoSuchBeanDefinitionException - if no bean of the given type was foundNoUniqueBeanDefinitionException - if more than one bean of the given type was foundBeansException - if the bean could not be createdListableBeanFactoryObject getBean(String name, Object... args) throws BeansException
Allows for specifying explicit constructor arguments / factory method arguments, overriding the specified default arguments (if any) in the bean definition.
name - the name of the bean to retrieveargs - arguments to use when creating a prototype using explicit argumentsNoSuchBeanDefinitionException - if there is no such bean definitionBeanDefinitionStoreException - if arguments have been given but
the affected bean isn't a prototypeBeansException - if the bean could not be createdboolean containsBean(String 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.
name - the name of the bean to queryboolean isSingleton(String name) throws NoSuchBeanDefinitionException
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.
name - the name of the bean to queryNoSuchBeanDefinitionException - if there is no bean with the given namegetBean(java.lang.String),
isPrototype(java.lang.String)boolean isPrototype(String name) throws NoSuchBeanDefinitionException
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.
name - the name of the bean to queryNoSuchBeanDefinitionException - if there is no bean with the given namegetBean(java.lang.String),
isSingleton(java.lang.String)boolean isTypeMatch(String name, Class<?> targetType) throws NoSuchBeanDefinitionException
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.
name - the name of the bean to querytargetType - the type to match againsttrue if the bean type matches,
false if it doesn't match or cannot be determined yetNoSuchBeanDefinitionException - if there is no bean with the given namegetBean(java.lang.String),
getType(java.lang.String)Class<?> getType(String name) throws NoSuchBeanDefinitionException
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.
name - the name of the bean to querynull if not determinableNoSuchBeanDefinitionException - if there is no bean with the given namegetBean(java.lang.String),
isTypeMatch(java.lang.String, java.lang.Class<?>)String[] getAliases(String name)
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.
name - the bean name to check for aliasesgetBean(java.lang.String)