https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
/*
 * 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.context.annotation;

import java.beans.Introspector;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;


BeanNameGenerator implementation for bean classes annotated with the @Component annotation or with another annotation that is itself annotated with @Component as a meta-annotation. For example, Spring's stereotype annotations (such as @Repository) are themselves annotated with @Component. 
Also supports Java EE 6's ManagedBean and JSR-330's Named annotations, if available. Note that Spring component annotations always override such standard annotations. 
If the annotation's value doesn't indicate a bean name, an appropriate
name will be built based on the short name of the class (with the first
letter lower-cased). For example:

com.xyz.FooServiceImpl -> fooServiceImpl


Author:Juergen Hoeller, Mark Fisher
See Also:
Since:2.5
/**
 * {@link BeanNameGenerator} implementation for bean classes annotated with the
 * {@link org.springframework.stereotype.Component @Component} annotation or
 * with another annotation that is itself annotated with {@code @Component} as a
 * meta-annotation. For example, Spring's stereotype annotations (such as
 * {@link org.springframework.stereotype.Repository @Repository}) are
 * themselves annotated with {@code @Component}.
 *
 * <p>Also supports Java EE 6's {@link javax.annotation.ManagedBean} and
 * JSR-330's {@link javax.inject.Named} annotations, if available. Note that
 * Spring component annotations always override such standard annotations.
 *
 * <p>If the annotation's value doesn't indicate a bean name, an appropriate
 * name will be built based on the short name of the class (with the first
 * letter lower-cased). For example:
 *
 * <pre class="code">com.xyz.FooServiceImpl -&gt; fooServiceImpl</pre>
 *
 * @author Juergen Hoeller
 * @author Mark Fisher
 * @since 2.5
 * @see org.springframework.stereotype.Component#value()
 * @see org.springframework.stereotype.Repository#value()
 * @see org.springframework.stereotype.Service#value()
 * @see org.springframework.stereotype.Controller#value()
 * @see javax.inject.Named#value()
 * @see FullyQualifiedAnnotationBeanNameGenerator
 */
public class AnnotationBeanNameGenerator implements BeanNameGenerator {

	
A convenient constant for a default AnnotationBeanNameGenerator instance, as used for component scanning purposes. 
Since:5.2
/**
	 * A convenient constant for a default {@code AnnotationBeanNameGenerator} instance,
	 * as used for component scanning purposes.
	 * @since 5.2
	 */
	public static final AnnotationBeanNameGenerator INSTANCE = new AnnotationBeanNameGenerator();

	private static final String COMPONENT_ANNOTATION_CLASSNAME = "org.springframework.stereotype.Component";

	private final Map<String, Set<String>> metaAnnotationTypesCache = new ConcurrentHashMap<>();


	@Override
	public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
		if (definition instanceof AnnotatedBeanDefinition) {
			String beanName = determineBeanNameFromAnnotation((AnnotatedBeanDefinition) definition);
			if (StringUtils.hasText(beanName)) {
				// Explicit bean name found.
				return beanName;
			}
		}
		// Fallback: generate a unique default bean name.
		return buildDefaultBeanName(definition, registry);
	}

	
Derive a bean name from one of the annotations on the class.

Params:
  • annotatedDef – the annotation-aware bean definition
Returns:the bean name, or null if none is found
/**
	 * Derive a bean name from one of the annotations on the class.
	 * @param annotatedDef the annotation-aware bean definition
	 * @return the bean name, or {@code null} if none is found
	 */
	@Nullable
	protected String determineBeanNameFromAnnotation(AnnotatedBeanDefinition annotatedDef) {
		AnnotationMetadata amd = annotatedDef.getMetadata();
		Set<String> types = amd.getAnnotationTypes();
		String beanName = null;
		for (String type : types) {
			AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(amd, type);
			if (attributes != null) {
				Set<String> metaTypes = this.metaAnnotationTypesCache.computeIfAbsent(type, key -> {
					Set<String> result = amd.getMetaAnnotationTypes(key);
					return (result.isEmpty() ? Collections.emptySet() : result);
				});
				if (isStereotypeWithNameValue(type, metaTypes, attributes)) {
					Object value = attributes.get("value");
					if (value instanceof String) {
						String strVal = (String) value;
						if (StringUtils.hasLength(strVal)) {
							if (beanName != null && !strVal.equals(beanName)) {
								throw new IllegalStateException("Stereotype annotations suggest inconsistent " +
										"component names: '" + beanName + "' versus '" + strVal + "'");
							}
							beanName = strVal;
						}
					}
				}
			}
		}
		return beanName;
	}

	
Check whether the given annotation is a stereotype that is allowed to suggest a component name through its annotation value(). 
Params:
  • annotationType – the name of the annotation class to check
  • metaAnnotationTypes – the names of meta-annotations on the given annotation
  • attributes – the map of attributes for the given annotation
Returns:whether the annotation qualifies as a stereotype with component name
/**
	 * Check whether the given annotation is a stereotype that is allowed
	 * to suggest a component name through its annotation {@code value()}.
	 * @param annotationType the name of the annotation class to check
	 * @param metaAnnotationTypes the names of meta-annotations on the given annotation
	 * @param attributes the map of attributes for the given annotation
	 * @return whether the annotation qualifies as a stereotype with component name
	 */
	protected boolean isStereotypeWithNameValue(String annotationType,
			Set<String> metaAnnotationTypes, @Nullable Map<String, Object> attributes) {

		boolean isStereotype = annotationType.equals(COMPONENT_ANNOTATION_CLASSNAME) ||
				metaAnnotationTypes.contains(COMPONENT_ANNOTATION_CLASSNAME) ||
				annotationType.equals("javax.annotation.ManagedBean") ||
				annotationType.equals("javax.inject.Named");

		return (isStereotype && attributes != null && attributes.containsKey("value"));
	}

	
Derive a default bean name from the given bean definition.

The default implementation delegates to buildDefaultBeanName(BeanDefinition). 
Params:
  • definition – the bean definition to build a bean name for
  • registry – the registry that the given bean definition is being registered with
Returns:the default bean name (never null)
/**
	 * Derive a default bean name from the given bean definition.
	 * <p>The default implementation delegates to {@link #buildDefaultBeanName(BeanDefinition)}.
	 * @param definition the bean definition to build a bean name for
	 * @param registry the registry that the given bean definition is being registered with
	 * @return the default bean name (never {@code null})
	 */
	protected String buildDefaultBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
		return buildDefaultBeanName(definition);
	}

	
Derive a default bean name from the given bean definition.

The default implementation simply builds a decapitalized version
of the short class name: e.g. "mypackage.MyJdbcDao" -> "myJdbcDao".

Note that inner classes will thus have names of the form
"outerClassName.InnerClassName", which because of the period in the
name may be an issue if you are autowiring by name.

Params:
  • definition – the bean definition to build a bean name for
Returns:the default bean name (never null)
/**
	 * Derive a default bean name from the given bean definition.
	 * <p>The default implementation simply builds a decapitalized version
	 * of the short class name: e.g. "mypackage.MyJdbcDao" -> "myJdbcDao".
	 * <p>Note that inner classes will thus have names of the form
	 * "outerClassName.InnerClassName", which because of the period in the
	 * name may be an issue if you are autowiring by name.
	 * @param definition the bean definition to build a bean name for
	 * @return the default bean name (never {@code null})
	 */
	protected String buildDefaultBeanName(BeanDefinition definition) {
		String beanClassName = definition.getBeanClassName();
		Assert.state(beanClassName != null, "No bean class name set");
		String shortClassName = ClassUtils.getShortName(beanClassName);
		return Introspector.decapitalize(shortClassName);
	}

}