org.springframework.beans.factory.support.AutowireCandidateResolver Maven / Gradle / Ivy
/*
* Copyright 2002-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.beans.factory.support;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.config.DependencyDescriptor;
import org.springframework.lang.Nullable;
/**
* Strategy interface for determining whether a specific bean definition
* qualifies as an autowire candidate for a specific dependency.
*
* @author Juergen Hoeller
* @author Mark Fisher
* @since 2.5
*/
public interface AutowireCandidateResolver {
/**
* Determine whether the given bean definition qualifies as an
* autowire candidate for the given dependency.
* The default implementation checks
* {@link org.springframework.beans.factory.config.BeanDefinition#isAutowireCandidate()}.
* @param bdHolder the bean definition including bean name and aliases
* @param descriptor the descriptor for the target method parameter or field
* @return whether the bean definition qualifies as autowire candidate
* @see org.springframework.beans.factory.config.BeanDefinition#isAutowireCandidate()
*/
default boolean isAutowireCandidate(BeanDefinitionHolder bdHolder, DependencyDescriptor descriptor) {
return bdHolder.getBeanDefinition().isAutowireCandidate();
}
/**
* Determine whether the given descriptor is effectively required.
*
The default implementation checks {@link DependencyDescriptor#isRequired()}.
* @param descriptor the descriptor for the target method parameter or field
* @return whether the descriptor is marked as required or possibly indicating
* non-required status some other way (e.g. through a parameter annotation)
* @since 5.0
* @see DependencyDescriptor#isRequired()
*/
default boolean isRequired(DependencyDescriptor descriptor) {
return descriptor.isRequired();
}
/**
* Determine whether the given descriptor declares a qualifier beyond the type
* (typically - but not necessarily - a specific kind of annotation).
*
The default implementation returns {@code false}.
* @param descriptor the descriptor for the target method parameter or field
* @return whether the descriptor declares a qualifier, narrowing the candidate
* status beyond the type match
* @since 5.1
* @see org.springframework.beans.factory.annotation.QualifierAnnotationAutowireCandidateResolver#hasQualifier
*/
default boolean hasQualifier(DependencyDescriptor descriptor) {
return false;
}
/**
* Determine whether a default value is suggested for the given dependency.
*
The default implementation simply returns {@code null}.
* @param descriptor the descriptor for the target method parameter or field
* @return the value suggested (typically an expression String),
* or {@code null} if none found
* @since 3.0
*/
@Nullable
default Object getSuggestedValue(DependencyDescriptor descriptor) {
return null;
}
/**
* Build a proxy for lazy resolution of the actual dependency target,
* if demanded by the injection point.
*
The default implementation simply returns {@code null}.
* @param descriptor the descriptor for the target method parameter or field
* @param beanName the name of the bean that contains the injection point
* @return the lazy resolution proxy for the actual dependency target,
* or {@code null} if straight resolution is to be performed
* @since 4.0
*/
@Nullable
default Object getLazyResolutionProxyIfNecessary(DependencyDescriptor descriptor, @Nullable String beanName) {
return null;
}
/**
* Return a clone of this resolver instance if necessary, retaining its local
* configuration and allowing for the cloned instance to get associated with
* a new bean factory, or this original instance if there is no such state.
*
The default implementation creates a separate instance via the default
* class constructor, assuming no specific configuration state to copy.
* Subclasses may override this with custom configuration state handling
* or with standard {@link Cloneable} support (as implemented by Spring's
* own configurable {@code AutowireCandidateResolver} variants), or simply
* return {@code this} (as in {@link SimpleAutowireCandidateResolver}).
* @since 5.2.7
* @see GenericTypeAwareAutowireCandidateResolver#cloneIfNecessary()
* @see DefaultListableBeanFactory#copyConfigurationFrom
*/
default AutowireCandidateResolver cloneIfNecessary() {
return BeanUtils.instantiateClass(getClass());
}
}