001/* 002 * Copyright 2002-2018 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.core.annotation; 018 019import java.lang.reflect.AnnotatedElement; 020import java.lang.reflect.Method; 021import java.util.Arrays; 022import java.util.Collections; 023import java.util.List; 024 025import org.springframework.core.DecoratingProxy; 026import org.springframework.core.OrderComparator; 027 028/** 029 * {@code AnnotationAwareOrderComparator} is an extension of 030 * {@link OrderComparator} that supports Spring's 031 * {@link org.springframework.core.Ordered} interface as well as the 032 * {@link Order @Order} and {@link javax.annotation.Priority @Priority} 033 * annotations, with an order value provided by an {@code Ordered} 034 * instance overriding a statically defined annotation value (if any). 035 * 036 * <p>Consult the Javadoc for {@link OrderComparator} for details on the 037 * sort semantics for non-ordered objects. 038 * 039 * @author Juergen Hoeller 040 * @author Oliver Gierke 041 * @author Stephane Nicoll 042 * @since 2.0.1 043 * @see org.springframework.core.Ordered 044 * @see org.springframework.core.annotation.Order 045 * @see javax.annotation.Priority 046 */ 047public class AnnotationAwareOrderComparator extends OrderComparator { 048 049 /** 050 * Shared default instance of {@code AnnotationAwareOrderComparator}. 051 */ 052 public static final AnnotationAwareOrderComparator INSTANCE = new AnnotationAwareOrderComparator(); 053 054 055 /** 056 * This implementation checks for {@link Order @Order} or 057 * {@link javax.annotation.Priority @Priority} on various kinds of 058 * elements, in addition to the {@link org.springframework.core.Ordered} 059 * check in the superclass. 060 */ 061 @Override 062 protected Integer findOrder(Object obj) { 063 // Check for regular Ordered interface 064 Integer order = super.findOrder(obj); 065 if (order != null) { 066 return order; 067 } 068 069 // Check for @Order and @Priority on various kinds of elements 070 if (obj instanceof Class) { 071 return OrderUtils.getOrder((Class<?>) obj); 072 } 073 else if (obj instanceof Method) { 074 Order ann = AnnotationUtils.findAnnotation((Method) obj, Order.class); 075 if (ann != null) { 076 return ann.value(); 077 } 078 } 079 else if (obj instanceof AnnotatedElement) { 080 Order ann = AnnotationUtils.getAnnotation((AnnotatedElement) obj, Order.class); 081 if (ann != null) { 082 return ann.value(); 083 } 084 } 085 else if (obj != null) { 086 order = OrderUtils.getOrder(obj.getClass()); 087 if (order == null && obj instanceof DecoratingProxy) { 088 order = OrderUtils.getOrder(((DecoratingProxy) obj).getDecoratedClass()); 089 } 090 } 091 092 return order; 093 } 094 095 /** 096 * This implementation retrieves an @{@link javax.annotation.Priority} 097 * value, allowing for additional semantics over the regular @{@link Order} 098 * annotation: typically, selecting one object over another in case of 099 * multiple matches but only one object to be returned. 100 */ 101 @Override 102 public Integer getPriority(Object obj) { 103 Integer priority = null; 104 if (obj instanceof Class) { 105 priority = OrderUtils.getPriority((Class<?>) obj); 106 } 107 else if (obj != null) { 108 priority = OrderUtils.getPriority(obj.getClass()); 109 if (priority == null && obj instanceof DecoratingProxy) { 110 priority = OrderUtils.getPriority(((DecoratingProxy) obj).getDecoratedClass()); 111 } 112 } 113 return priority; 114 } 115 116 117 /** 118 * Sort the given List with a default AnnotationAwareOrderComparator. 119 * <p>Optimized to skip sorting for lists with size 0 or 1, 120 * in order to avoid unnecessary array extraction. 121 * @param list the List to sort 122 * @see java.util.Collections#sort(java.util.List, java.util.Comparator) 123 */ 124 public static void sort(List<?> list) { 125 if (list.size() > 1) { 126 Collections.sort(list, INSTANCE); 127 } 128 } 129 130 /** 131 * Sort the given array with a default AnnotationAwareOrderComparator. 132 * <p>Optimized to skip sorting for lists with size 0 or 1, 133 * in order to avoid unnecessary array extraction. 134 * @param array the array to sort 135 * @see java.util.Arrays#sort(Object[], java.util.Comparator) 136 */ 137 public static void sort(Object[] array) { 138 if (array.length > 1) { 139 Arrays.sort(array, INSTANCE); 140 } 141 } 142 143 /** 144 * Sort the given array or List with a default AnnotationAwareOrderComparator, 145 * if necessary. Simply skips sorting when given any other value. 146 * <p>Optimized to skip sorting for lists with size 0 or 1, 147 * in order to avoid unnecessary array extraction. 148 * @param value the array or List to sort 149 * @see java.util.Arrays#sort(Object[], java.util.Comparator) 150 */ 151 public static void sortIfNecessary(Object value) { 152 if (value instanceof Object[]) { 153 sort((Object[]) value); 154 } 155 else if (value instanceof List) { 156 sort((List<?>) value); 157 } 158 } 159 160}