org.springframework.core.annotation.AbstractAliasAwareAnnotationAttributeExtractor Maven / Gradle / Ivy
/*
* Copyright 2002-2016 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.core.annotation;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* Abstract base class for {@link AnnotationAttributeExtractor} implementations
* that transparently enforce attribute alias semantics for annotation
* attributes that are annotated with {@link AliasFor @AliasFor}.
*
* @author Sam Brannen
* @since 4.2
* @param the type of source supported by this extractor
* @see Annotation
* @see AliasFor
* @see AnnotationUtils#synthesizeAnnotation(Annotation, Object)
*/
abstract class AbstractAliasAwareAnnotationAttributeExtractor implements AnnotationAttributeExtractor {
private final Class annotationType;
@Nullable
private final Object annotatedElement;
private final S source;
private final Map> attributeAliasMap;
/**
* Construct a new {@code AbstractAliasAwareAnnotationAttributeExtractor}.
* @param annotationType the annotation type to synthesize; never {@code null}
* @param annotatedElement the element that is annotated with the annotation
* of the supplied type; may be {@code null} if unknown
* @param source the underlying source of annotation attributes; never {@code null}
*/
AbstractAliasAwareAnnotationAttributeExtractor(
Class annotationType, @Nullable Object annotatedElement, S source) {
Assert.notNull(annotationType, "annotationType must not be null");
Assert.notNull(source, "source must not be null");
this.annotationType = annotationType;
this.annotatedElement = annotatedElement;
this.source = source;
this.attributeAliasMap = AnnotationUtils.getAttributeAliasMap(annotationType);
}
@Override
public final Class getAnnotationType() {
return this.annotationType;
}
@Override
@Nullable
public final Object getAnnotatedElement() {
return this.annotatedElement;
}
@Override
public final S getSource() {
return this.source;
}
@Override
@Nullable
public final Object getAttributeValue(Method attributeMethod) {
String attributeName = attributeMethod.getName();
Object attributeValue = getRawAttributeValue(attributeMethod);
List aliasNames = this.attributeAliasMap.get(attributeName);
if (aliasNames != null) {
Object defaultValue = AnnotationUtils.getDefaultValue(this.annotationType, attributeName);
for (String aliasName : aliasNames) {
Object aliasValue = getRawAttributeValue(aliasName);
if (!ObjectUtils.nullSafeEquals(attributeValue, aliasValue) &&
!ObjectUtils.nullSafeEquals(attributeValue, defaultValue) &&
!ObjectUtils.nullSafeEquals(aliasValue, defaultValue)) {
String elementName = (this.annotatedElement != null ? this.annotatedElement.toString() : "unknown element");
throw new AnnotationConfigurationException(String.format(
"In annotation [%s] declared on %s and synthesized from [%s], attribute '%s' and its " +
"alias '%s' are present with values of [%s] and [%s], but only one is permitted.",
this.annotationType.getName(), elementName, this.source, attributeName, aliasName,
ObjectUtils.nullSafeToString(attributeValue), ObjectUtils.nullSafeToString(aliasValue)));
}
// If the user didn't declare the annotation with an explicit value,
// use the value of the alias instead.
if (ObjectUtils.nullSafeEquals(attributeValue, defaultValue)) {
attributeValue = aliasValue;
}
}
}
return attributeValue;
}
/**
* Get the raw, unmodified attribute value from the underlying
* {@linkplain #getSource source} that corresponds to the supplied
* attribute method.
*/
@Nullable
protected abstract Object getRawAttributeValue(Method attributeMethod);
/**
* Get the raw, unmodified attribute value from the underlying
* {@linkplain #getSource source} that corresponds to the supplied
* attribute name.
*/
@Nullable
protected abstract Object getRawAttributeValue(String attributeName);
}