001/* 002 * Copyright 2002-2017 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.context.annotation; 018 019import java.lang.annotation.Documented; 020import java.lang.annotation.ElementType; 021import java.lang.annotation.Retention; 022import java.lang.annotation.RetentionPolicy; 023import java.lang.annotation.Target; 024 025/** 026 * Indicates that a component is only eligible for registration when all 027 * {@linkplain #value specified conditions} match. 028 * 029 * <p>A <em>condition</em> is any state that can be determined programmatically 030 * before the bean definition is due to be registered (see {@link Condition} for details). 031 * 032 * <p>The {@code @Conditional} annotation may be used in any of the following ways: 033 * <ul> 034 * <li>as a type-level annotation on any class directly or indirectly annotated with 035 * {@code @Component}, including {@link Configuration @Configuration} classes</li> 036 * <li>as a meta-annotation, for the purpose of composing custom stereotype 037 * annotations</li> 038 * <li>as a method-level annotation on any {@link Bean @Bean} method</li> 039 * </ul> 040 * 041 * <p>If a {@code @Configuration} class is marked with {@code @Conditional}, 042 * all of the {@code @Bean} methods, {@link Import @Import} annotations, and 043 * {@link ComponentScan @ComponentScan} annotations associated with that 044 * class will be subject to the conditions. 045 * 046 * <p><strong>NOTE</strong>: Inheritance of {@code @Conditional} annotations 047 * is not supported; any conditions from superclasses or from overridden 048 * methods will not be considered. In order to enforce these semantics, 049 * {@code @Conditional} itself is not declared as 050 * {@link java.lang.annotation.Inherited @Inherited}; furthermore, any 051 * custom <em>composed annotation</em> that is meta-annotated with 052 * {@code @Conditional} must not be declared as {@code @Inherited}. 053 * 054 * @author Phillip Webb 055 * @author Sam Brannen 056 * @since 4.0 057 * @see Condition 058 */ 059@Target({ElementType.TYPE, ElementType.METHOD}) 060@Retention(RetentionPolicy.RUNTIME) 061@Documented 062public @interface Conditional { 063 064 /** 065 * All {@link Condition}s that must {@linkplain Condition#matches match} 066 * in order for the component to be registered. 067 */ 068 Class<? extends Condition>[] value(); 069 070}