org.springframework.core.annotation.AnnotationAwareOrderComparator Maven / Gradle / Ivy
/*
* Copyright 2002-2014 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.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.springframework.core.OrderComparator;
/**
* {@link java.util.Comparator} implementation that checks Spring's
* {@link org.springframework.core.Ordered} interface as well as the
* {@link Order} annotation and the {@link javax.annotation.Priority}
* annotation, with an order value provided by an {@code Ordered}
* instance overriding a statically defined annotation value (if any).
*
* @author Juergen Hoeller
* @author Oliver Gierke
* @author Stephane Nicoll
* @since 2.0.1
* @see org.springframework.core.Ordered
* @see Order
* @see javax.annotation.Priority
*/
public class AnnotationAwareOrderComparator extends OrderComparator {
/**
* Shared default instance of AnnotationAwareOrderComparator.
*/
public static final AnnotationAwareOrderComparator INSTANCE = new AnnotationAwareOrderComparator();
/**
* This implementation checks for the {@link Order} annotation
* on various kinds of elements, in addition to the
* {@link org.springframework.core.Ordered} check in the superclass.
*/
protected Integer findOrder(Object obj) {
// Check for regular Ordered interface
Integer order = super.findOrder(obj);
if (order != null) {
return order;
}
// Check for @Order annotation on various kinds of elements
if (obj instanceof Class) {
return OrderUtils.getOrder((Class) obj);
}
else if (obj instanceof Method) {
Order ann = AnnotationUtils.findAnnotation((Method) obj, Order.class);
if (ann != null) {
return ann.value();
}
}
else if (obj instanceof AnnotatedElement) {
Order ann = AnnotationUtils.getAnnotation((AnnotatedElement) obj, Order.class);
if (ann != null) {
return ann.value();
}
}
else if (obj != null) {
return OrderUtils.getOrder(obj.getClass());
}
return null;
}
/**
* This implementation checks retrieves a {@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.
*/
public Integer getPriority(Object obj) {
if (obj instanceof Class) {
return OrderUtils.getPriority((Class) obj);
}
else if (obj != null) {
return OrderUtils.getPriority(obj.getClass());
}
return null;
}
/**
* Sort the given List with a default 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.Collections#sort(java.util.List, java.util.Comparator)
*/
public static void sort(List list) {
if (list.size() > 1) {
Collections.sort(list, 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);
}
}
}