org.springframework.core.annotation.AnnotationAwareOrderComparator Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.core.annotation;
import java.lang.reflect.AnnotatedElement;
import java.util.Arrays;
import java.util.List;
import org.springframework.core.DecoratingProxy;
import org.springframework.core.OrderComparator;
import org.springframework.core.annotation.MergedAnnotations.SearchStrategy;
import org.springframework.lang.Nullable;
/**
* {@code AnnotationAwareOrderComparator} is an extension of
* {@link OrderComparator} that supports Spring's
* {@link org.springframework.core.Ordered} interface as well as the
* {@link Order @Order} and {@link javax.annotation.Priority @Priority}
* annotations, with an order value provided by an {@code Ordered}
* instance overriding a statically defined annotation value (if any).
*
* Consult the Javadoc for {@link OrderComparator} for details on the
* sort semantics for non-ordered objects.
*
* @author Juergen Hoeller
* @author Oliver Gierke
* @author Stephane Nicoll
* @since 2.0.1
* @see org.springframework.core.Ordered
* @see org.springframework.core.annotation.Order
* @see javax.annotation.Priority
*/
public class AnnotationAwareOrderComparator extends OrderComparator {
/**
* Shared default instance of {@code AnnotationAwareOrderComparator}.
*/
public static final AnnotationAwareOrderComparator INSTANCE = new AnnotationAwareOrderComparator();
/**
* This implementation checks for {@link Order @Order} or
* {@link javax.annotation.Priority @Priority} on various kinds of
* elements, in addition to the {@link org.springframework.core.Ordered}
* check in the superclass.
*/
@Override
@Nullable
protected Integer findOrder(Object obj) {
Integer order = super.findOrder(obj);
if (order != null) {
return order;
}
return findOrderFromAnnotation(obj);
}
@Nullable
private Integer findOrderFromAnnotation(Object obj) {
AnnotatedElement element = (obj instanceof AnnotatedElement ? (AnnotatedElement) obj : obj.getClass());
MergedAnnotations annotations = MergedAnnotations.from(element, SearchStrategy.TYPE_HIERARCHY);
Integer order = OrderUtils.getOrderFromAnnotations(element, annotations);
if (order == null && obj instanceof DecoratingProxy) {
return findOrderFromAnnotation(((DecoratingProxy) obj).getDecoratedClass());
}
return order;
}
/**
* This implementation retrieves an @{@link javax.annotation.Priority}
* value, allowing for additional semantics over the regular @{@link Order}
* annotation: typically, selecting one object over another in case of
* multiple matches but only one object to be returned.
*/
@Override
@Nullable
public Integer getPriority(Object obj) {
if (obj instanceof Class) {
return OrderUtils.getPriority((Class) obj);
}
Integer priority = OrderUtils.getPriority(obj.getClass());
if (priority == null && obj instanceof DecoratingProxy) {
return getPriority(((DecoratingProxy) obj).getDecoratedClass());
}
return priority;
}
/**
* Sort the given list with a default {@link AnnotationAwareOrderComparator}.
*
Optimized to skip sorting for lists with size 0 or 1,
* in order to avoid unnecessary array extraction.
* @param list the List to sort
* @see java.util.List#sort(java.util.Comparator)
*/
public static void sort(List list) {
if (list.size() > 1) {
list.sort(INSTANCE);
}
}
/**
* Sort the given array with a default AnnotationAwareOrderComparator.
*
Optimized to skip sorting for lists with size 0 or 1,
* in order to avoid unnecessary array extraction.
* @param array the array to sort
* @see java.util.Arrays#sort(Object[], java.util.Comparator)
*/
public static void sort(Object[] array) {
if (array.length > 1) {
Arrays.sort(array, INSTANCE);
}
}
/**
* Sort the given array or List with a default AnnotationAwareOrderComparator,
* if necessary. Simply skips sorting when given any other value.
*
Optimized to skip sorting for lists with size 0 or 1,
* in order to avoid unnecessary array extraction.
* @param value the array or List to sort
* @see java.util.Arrays#sort(Object[], java.util.Comparator)
*/
public static void sortIfNecessary(Object value) {
if (value instanceof Object[]) {
sort((Object[]) value);
}
else if (value instanceof List) {
sort((List) value);
}
}
}