Package org.springframework.beans.factory.annotation

Class AutowiredAnnotationBeanPostProcessor

java.lang.Object
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor
All Implemented Interfaces:
Aware, BeanFactoryAware, BeanPostProcessor, InstantiationAwareBeanPostProcessor, SmartInstantiationAwareBeanPostProcessor, AotContributingBeanPostProcessor, MergedBeanDefinitionPostProcessor, Ordered, PriorityOrdered
public class AutowiredAnnotationBeanPostProcessor extends Object implements SmartInstantiationAwareBeanPostProcessor, MergedBeanDefinitionPostProcessor, AotContributingBeanPostProcessor, PriorityOrdered, BeanFactoryAware
BeanPostProcessor implementation that autowires annotated fields, setter methods, and arbitrary config methods. Such members to be injected are detected through annotations: by default, Spring's @Autowired and @Value annotations.

Also supports the common @Inject annotation, if available, as a direct alternative to Spring's own @Autowired. Additionally, it retains support for the javax.inject.Inject variant dating back to the original JSR-330 specification (as known from Java EE 6-8).

Autowired Constructors

Only one constructor of any given bean class may declare this annotation with the 'required' attribute set to true, indicating the constructor to autowire when used as a Spring bean. Furthermore, if the 'required' attribute is set to true, only a single constructor may be annotated with @Autowired. If multiple non-required constructors declare the annotation, they will be considered as candidates for autowiring. The constructor with the greatest number of dependencies that can be satisfied by matching beans in the Spring container will be chosen. If none of the candidates can be satisfied, then a primary/default constructor (if present) will be used. If a class only declares a single constructor to begin with, it will always be used, even if not annotated. An annotated constructor does not have to be public.

Autowired Fields

Fields are injected right after construction of a bean, before any config methods are invoked. Such a config field does not have to be public.

Autowired Methods

Config methods may have an arbitrary name and any number of arguments; each of those arguments will be autowired with a matching bean in the Spring container. Bean property setter methods are effectively just a special case of such a general config method. Config methods do not have to be public.

Annotation Config vs. XML Config

A default AutowiredAnnotationBeanPostProcessor will be registered by the "context:annotation-config" and "context:component-scan" XML tags. Remove or turn off the default annotation configuration there if you intend to specify a custom AutowiredAnnotationBeanPostProcessor bean definition.

NOTE: Annotation injection will be performed before XML injection; thus the latter configuration will override the former for properties wired through both approaches.

@Lookup Methods

In addition to regular injection points as discussed above, this post-processor also handles Spring's @Lookup annotation which identifies lookup methods to be replaced by the container at runtime. This is essentially a type-safe version of getBean(Class, args) and getBean(String, args). See @Lookup's javadoc for details.

Since:
2.5
Author:
Juergen Hoeller, Mark Fisher, Stephane Nicoll, Sebastien Deleuze, Sam Brannen
See Also:

  • Field Details

    • logger

      protected final Log logger

  • Constructor Details

    • AutowiredAnnotationBeanPostProcessor

      public AutowiredAnnotationBeanPostProcessor()
      Create a new AutowiredAnnotationBeanPostProcessor for Spring's standard @Autowired and @Value annotations.

      Also supports the common @Inject annotation, if available, as well as the original javax.inject.Inject variant.

  • Method Details

    • setAutowiredAnnotationType

      public void setAutowiredAnnotationType(Class<? extends Annotation> autowiredAnnotationType)
      Set the 'autowired' annotation type, to be used on constructors, fields, setter methods, and arbitrary config methods.

      The default autowired annotation types are the Spring-provided @Autowired and @Value annotations as well as the common @Inject annotation, if available.

      This setter property exists so that developers can provide their own (non-Spring-specific) annotation type to indicate that a member is supposed to be autowired.

    • setAutowiredAnnotationTypes

      public void setAutowiredAnnotationTypes(Set<Class<? extends Annotation>> autowiredAnnotationTypes)
      Set the 'autowired' annotation types, to be used on constructors, fields, setter methods, and arbitrary config methods.

      The default autowired annotation types are the Spring-provided @Autowired and @Value annotations as well as the common @Inject annotation, if available.

      This setter property exists so that developers can provide their own (non-Spring-specific) annotation types to indicate that a member is supposed to be autowired.

    • setRequiredParameterName

      public void setRequiredParameterName(String requiredParameterName)
      Set the name of an attribute of the annotation that specifies whether it is required.
      See Also:

    • setRequiredParameterValue

      public void setRequiredParameterValue(boolean requiredParameterValue)
      Set the boolean value that marks a dependency as required.

      For example if using 'required=true' (the default), this value should be true; but if using 'optional=false', this value should be false.

      See Also:

    • setOrder

      public void setOrder(int order)

    • getOrder

      public int getOrder()
      Description copied from interface: Ordered
      Get the order value of this object.

      Higher values are interpreted as lower priority. As a consequence, the object with the lowest value has the highest priority (somewhat analogous to Servlet load-on-startup values).

      Same order values will result in arbitrary sort positions for the affected objects.

      Specified by:
      getOrder in interface Ordered
      Returns:
      the order value
      See Also:

    • setBeanFactory

      public void setBeanFactory(BeanFactory beanFactory)
      Description copied from interface: BeanFactoryAware
      Callback that supplies the owning factory to a bean instance.

      Invoked after the population of normal bean properties but before an initialization callback such as InitializingBean.afterPropertiesSet() or a custom init-method.

      Specified by:
      setBeanFactory in interface BeanFactoryAware
      Parameters:
      beanFactory - owning BeanFactory (never null). The bean can immediately call methods on the factory.
      See Also:

    • postProcessMergedBeanDefinition

      public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName)
      Description copied from interface: MergedBeanDefinitionPostProcessor
      Post-process the given merged bean definition for the specified bean.
      Specified by:
      postProcessMergedBeanDefinition in interface MergedBeanDefinitionPostProcessor
      Parameters:
      beanDefinition - the merged bean definition for the bean
      beanType - the actual type of the managed bean instance
      beanName - the name of the bean
      See Also:

    • contribute

      public BeanInstantiationContribution contribute(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName)
      Description copied from interface: AotContributingBeanPostProcessor
      Contribute a BeanInstantiationContribution for the given bean definition, if applicable.
      Specified by:
      contribute in interface AotContributingBeanPostProcessor
      Parameters:
      beanDefinition - the merged bean definition for the bean
      beanType - the inferred type of the bean
      beanName - the name of the bean
      Returns:
      the contribution to use or null if the bean should not be processed

    • resetBeanDefinition

      public void resetBeanDefinition(String beanName)
      Description copied from interface: MergedBeanDefinitionPostProcessor
      A notification that the bean definition for the specified name has been reset, and that this post-processor should clear any metadata for the affected bean.

      The default implementation is empty.

      Specified by:
      resetBeanDefinition in interface MergedBeanDefinitionPostProcessor
      Parameters:
      beanName - the name of the bean
      See Also:

    • determineCandidateConstructors

      @Nullable public Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeanCreationException
      Description copied from interface: SmartInstantiationAwareBeanPostProcessor
      Determine the candidate constructors to use for the given bean.

      The default implementation returns null.

      Specified by:
      determineCandidateConstructors in interface SmartInstantiationAwareBeanPostProcessor
      Parameters:
      beanClass - the raw class of the bean (never null)
      beanName - the name of the bean
      Returns:
      the candidate constructors, or null if none specified
      Throws:
      BeanCreationException

    • postProcessProperties

      public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName)
      Description copied from interface: InstantiationAwareBeanPostProcessor
      Post-process the given property values before the factory applies them to the given bean.

      The default implementation returns the given pvs as-is.

      Specified by:
      postProcessProperties in interface InstantiationAwareBeanPostProcessor
      Parameters:
      pvs - the property values that the factory is about to apply (never null)
      bean - the bean instance created, but whose properties have not yet been set
      beanName - the name of the bean
      Returns:
      the actual property values to apply to the given bean (can be the passed-in PropertyValues instance), or null to skip property population

    • processInjection

      public void processInjection(Object bean) throws BeanCreationException
      'Native' processing method for direct calls with an arbitrary target instance, resolving all of its fields and methods which are annotated with one of the configured 'autowired' annotation types.
      Parameters:
      bean - the target instance to process
      Throws:
      BeanCreationException - if autowiring failed
      See Also:

    • determineRequiredStatus

      protected boolean determineRequiredStatus(MergedAnnotation<?> ann)
      Determine if the annotated field or method requires its dependency.

      A 'required' dependency means that autowiring should fail when no beans are found. Otherwise, the autowiring process will simply bypass the field or method when no beans are found.

      Parameters:
      ann - the Autowired annotation
      Returns:
      whether the annotation indicates that a dependency is required

    • determineRequiredStatus

      @Deprecated protected boolean determineRequiredStatus(AnnotationAttributes ann)
      Deprecated.
      since 5.2, in favor of determineRequiredStatus(MergedAnnotation)
      Determine if the annotated field or method requires its dependency.

      A 'required' dependency means that autowiring should fail when no beans are found. Otherwise, the autowiring process will simply bypass the field or method when no beans are found.

      Parameters:
      ann - the Autowired annotation
      Returns:
      whether the annotation indicates that a dependency is required

    • findAutowireCandidates

      protected <T> Map<String,T> findAutowireCandidates(Class<T> type) throws BeansException
      Obtain all beans of the given type as autowire candidates.
      Parameters:
      type - the type of the bean
      Returns:
      the target beans, or an empty Collection if no bean of this type is found
      Throws:
      BeansException - if bean retrieval failed