org.springframework.beans.factory.support
Class ConstructorResolver

java.lang.Object
  org.springframework.beans.factory.support.ConstructorResolver

abstract class ConstructorResolver
extends Object

Helper class for resolving constructors and factory methods. Performs constructor resolution through argument matching.

Works on an AbstractBeanFactory and an InstantiationStrategy. Used by AbstractAutowireCapableBeanFactory.

Since:

2.0

Author:

Juergen Hoeller

See Also:

autowireConstructor(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition), instantiateUsingFactoryMethod(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[]), AbstractAutowireCapableBeanFactory

Field Summary

protected Log

logger Logger available to subclasses

Constructor Summary

ConstructorResolver(AbstractBeanFactory beanFactory, InstantiationStrategy instantiationStrategy)
Create a new ConstructorResolver for the given factory and instantiation strategy.

Method Summary

protected BeanWrapper	autowireConstructor(String beanName, RootBeanDefinition mergedBeanDefinition) "autowire constructor" (with constructor arguments by type) behavior.
protected abstract Map	findAutowireCandidates(String beanName, Class requiredType) Find bean instances that match the required type.
BeanWrapper	instantiateUsingFactoryMethod(String beanName, RootBeanDefinition mergedBeanDefinition, Object[] explicitArgs) Instantiate the bean using a named factory method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected final Log logger

Logger available to subclasses

Constructor Detail

ConstructorResolver

public ConstructorResolver(AbstractBeanFactory beanFactory,
                           InstantiationStrategy instantiationStrategy)

Create a new ConstructorResolver for the given factory and instantiation strategy.

Parameters:

beanFactory - the BeanFactory to work with

instantiationStrategy - the instantiate strategy for creating bean instances

Method Detail

autowireConstructor

protected BeanWrapper autowireConstructor(String beanName,
                                          RootBeanDefinition mergedBeanDefinition)
                                   throws BeansException

"autowire constructor" (with constructor arguments by type) behavior. Also applied if explicit constructor argument values are specified, matching all remaining arguments with beans from the bean factory.

This corresponds to constructor injection: In this mode, a Spring bean factory is able to host components that expect constructor-based dependency resolution.

Parameters:

beanName - name of the bean

mergedBeanDefinition - the bean definition for the bean

Returns:

BeanWrapper for the new instance

Throws:

BeansException

instantiateUsingFactoryMethod

public BeanWrapper instantiateUsingFactoryMethod(String beanName,
                                                 RootBeanDefinition mergedBeanDefinition,
                                                 Object[] explicitArgs)
                                          throws BeansException

Instantiate the bean using a named factory method. The method may be static, if the mergedBeanDefinition parameter specifies a class, rather than a factoryBean, or an instance variable on a factory object itself configured using Dependency Injection.

Implementation requires iterating over the static or instance methods with the name specified in the RootBeanDefinition (the method may be overloaded) and trying to match with the parameters. We don't have the types attached to constructor args, so trial and error is the only way to go here. The explicitArgs array may contain argument values passed in programmatically via the corresponding getBean method.

Parameters:

beanName - name of the bean

mergedBeanDefinition - the bean definition for the bean

explicitArgs - argument values passed in programmatically via the getBean method, or null if none (-> use constructor argument values from bean definition)

Returns:

BeanWrapper for the new instance

Throws:

BeansException

findAutowireCandidates

protected abstract Map findAutowireCandidates(String beanName,
                                              Class requiredType)
                                       throws BeansException

Find bean instances that match the required type. Called during autowiring for the specified bean.

If a subclass cannot obtain information about bean names by type, a corresponding exception should be thrown.

Parameters:

beanName - the name of the bean that is about to be wired

requiredType - the type of the autowired constructor argument

Returns:

a Map of candidate names and candidate instances that match the required type (never null)

Throws:

BeansException - in case of errors

See Also:

autowireConstructor(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition)