public class

RequiredAnnotationBeanPostProcessor

extends InstantiationAwareBeanPostProcessorAdapter
implements BeanFactoryAware MergedBeanDefinitionPostProcessor PriorityOrdered
java.lang.Object
   ↳ org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter
     ↳ org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor

Class Overview

BeanPostProcessor implementation that enforces required JavaBean properties to have been configured. Required bean properties are detected through a Java 5 annotation: by default, Spring's Required annotation.

The motivation for the existence of this BeanPostProcessor is to allow developers to annotate the setter properties of their own classes with an arbitrary JDK 1.5 annotation to indicate that the container must check for the configuration of a dependency injected value. This neatly pushes responsibility for such checking onto the container (where it arguably belongs), and obviates the need (in part) for a developer to code a method that simply checks that all required properties have actually been set.

Please note that an 'init' method may still need to implemented (and may still be desirable), because all that this class does is enforce that a 'required' property has actually been configured with a value. It does not check anything else... In particular, it does not check that a configured value is not null.

Note: A default RequiredAnnotationBeanPostProcessor 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 RequiredAnnotationBeanPostProcessor bean definition.

See Also

Summary

[Expand]
Inherited Constants
From interface org.springframework.core.Ordered
Fields
public static final String SKIP_REQUIRED_CHECK_ATTRIBUTE Bean definition attribute that may indicate whether a given bean is supposed to be skipped when performing this post-processor's required property check.
Public Constructors
RequiredAnnotationBeanPostProcessor()
Public Methods
int getOrder()
Return the order value of this object, with a higher value meaning greater in terms of sorting.
void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class beanType, String beanName)
PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)
Post-process the given property values before the factory applies them to the given bean.
void setBeanFactory(BeanFactory beanFactory)
Callback that supplies the owning factory to a bean instance.
void setOrder(int order)
void setRequiredAnnotationType(Class<? extends Annotation> requiredAnnotationType)
Set the 'required' annotation type, to be used on bean property setter methods.
Protected Methods
Class<? extends Annotation> getRequiredAnnotationType()
Return the 'required' annotation type.
boolean isRequiredProperty(PropertyDescriptor propertyDescriptor)
Is the supplied property required to have a value (that is, to be dependency-injected)?

This implementation looks for the existence of a "required" annotation on the supplied property.

boolean shouldSkip(ConfigurableListableBeanFactory beanFactory, String beanName)
Check whether the given bean definition is not subject to the annotation-based required property check as performed by this post-processor.
[Expand]
Inherited Methods
From class org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter
From class java.lang.Object
From interface org.springframework.beans.factory.BeanFactoryAware
From interface org.springframework.beans.factory.config.BeanPostProcessor
From interface org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor
From interface org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor
From interface org.springframework.beans.factory.support.MergedBeanDefinitionPostProcessor
From interface org.springframework.core.Ordered

Fields

public static final String SKIP_REQUIRED_CHECK_ATTRIBUTE

Also: SpringBeans

Bean definition attribute that may indicate whether a given bean is supposed to be skipped when performing this post-processor's required property check.

See Also

Public Constructors

public RequiredAnnotationBeanPostProcessor ()

Also: SpringBeans

Public Methods

public int getOrder ()

Also: SpringBeans

Return the order value of this object, with a higher value meaning greater in terms of sorting.

Normally starting with 0, with Integer.MAX_VALUE indicating the greatest value. Same order values will result in arbitrary positions for the affected objects.

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

Returns
  • the order value

public void postProcessMergedBeanDefinition (RootBeanDefinition beanDefinition, Class beanType, String beanName)

Also: SpringBeans

public PropertyValues postProcessPropertyValues (PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)

Also: SpringBeans

Post-process the given property values before the factory applies them to the given bean. Allows for checking whether all dependencies have been satisfied, for example based on a "Required" annotation on bean property setters.

Also allows for replacing the property values to apply, typically through creating a new MutablePropertyValues instance based on the original PropertyValues, adding or removing specific values.

Parameters
pvs the property values that the factory is about to apply (never null)
pds the relevant property descriptors for the target bean (with ignored dependency types - which the factory handles specifically - already filtered out)
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 to the given bean (can be the passed-in PropertyValues instance), or null to skip property population
Throws
BeansException

public void setBeanFactory (BeanFactory beanFactory)

Also: SpringBeans

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 afterPropertiesSet() or a custom init-method.

Parameters
beanFactory owning BeanFactory (never null). The bean can immediately call methods on the factory.

public void setOrder (int order)

Also: SpringBeans

public void setRequiredAnnotationType (Class<? extends Annotation> requiredAnnotationType)

Also: SpringBeans

Set the 'required' annotation type, to be used on bean property setter methods.

The default required annotation type is the Spring-provided Required annotation.

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

Protected Methods

protected Class<? extends Annotation> getRequiredAnnotationType ()

Also: SpringBeans

Return the 'required' annotation type.

protected boolean isRequiredProperty (PropertyDescriptor propertyDescriptor)

Also: SpringBeans

Is the supplied property required to have a value (that is, to be dependency-injected)?

This implementation looks for the existence of a "required" annotation on the supplied property.

Parameters
propertyDescriptor the target PropertyDescriptor (never null)
Returns
  • true if the supplied property has been marked as being required; false if not, or if the supplied property does not have a setter method

protected boolean shouldSkip (ConfigurableListableBeanFactory beanFactory, String beanName)

Also: SpringBeans

Check whether the given bean definition is not subject to the annotation-based required property check as performed by this post-processor.

The default implementations check for the presence of the SKIP_REQUIRED_CHECK_ATTRIBUTE attribute in the bean definition, if any.

Parameters
beanFactory the BeanFactory to check against
beanName the name of the bean to check against
Returns
  • true to skip the bean; false to process it