/*
* Copyright 2002-2017 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
*
* http://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.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.config.DependencyDescriptor;
/**
* 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.
* <p>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.
* <p>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 a default value is suggested for the given dependency.
* <p>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
*/
default Object getSuggestedValue(DependencyDescriptor descriptor) {
return null;
}
/**
* Build a proxy for lazy resolution of the actual dependency target,
* if demanded by the injection point.
* <p>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
*/
default Object getLazyResolutionProxyIfNecessary(DependencyDescriptor descriptor, String beanName) {
return null;
}
}