001/* 002 * Copyright 2002-2019 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.annotation.Annotation; 020 021/** 022 * Strategy interface used to select between two {@link MergedAnnotation} 023 * instances. 024 * 025 * @author Phillip Webb 026 * @since 5.2 027 * @param <A> the annotation type 028 * @see MergedAnnotationSelectors 029 */ 030@FunctionalInterface 031public interface MergedAnnotationSelector<A extends Annotation> { 032 033 /** 034 * Determine if the existing annotation is known to be the best 035 * candidate and any subsequent selections may be skipped. 036 * @param annotation the annotation to check 037 * @return {@code true} if the annotation is known to be the best candidate 038 */ 039 default boolean isBestCandidate(MergedAnnotation<A> annotation) { 040 return false; 041 } 042 043 /** 044 * Select the annotation that should be used. 045 * @param existing an existing annotation returned from an earlier result 046 * @param candidate a candidate annotation that may be better suited 047 * @return the most appropriate annotation from the {@code existing} or 048 * {@code candidate} 049 */ 050 MergedAnnotation<A> select(MergedAnnotation<A> existing, MergedAnnotation<A> candidate); 051 052}