001/*
002 * Copyright 2002-2020 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 org.springframework.core.type.AnnotationMetadata;
020
021/**
022 * Interface to be implemented by types that determine which @{@link Configuration}
023 * class(es) should be imported based on a given selection criteria, usually one or
024 * more annotation attributes.
025 *
026 * <p>An {@link ImportSelector} may implement any of the following
027 * {@link org.springframework.beans.factory.Aware Aware} interfaces,
028 * and their respective methods will be called prior to {@link #selectImports}:
029 * <ul>
030 * <li>{@link org.springframework.context.EnvironmentAware EnvironmentAware}</li>
031 * <li>{@link org.springframework.beans.factory.BeanFactoryAware BeanFactoryAware}</li>
032 * <li>{@link org.springframework.beans.factory.BeanClassLoaderAware BeanClassLoaderAware}</li>
033 * <li>{@link org.springframework.context.ResourceLoaderAware ResourceLoaderAware}</li>
034 * </ul>
035 *
036 * <p>{@code ImportSelector} implementations are usually processed in the same way
037 * as regular {@code @Import} annotations, however, it is also possible to defer
038 * selection of imports until all {@code @Configuration} classes have been processed
039 * (see {@link DeferredImportSelector} for details).
040 *
041 * @author Chris Beams
042 * @since 3.1
043 * @see DeferredImportSelector
044 * @see Import
045 * @see ImportBeanDefinitionRegistrar
046 * @see Configuration
047 */
048public interface ImportSelector {
049
050        /**
051         * Select and return the names of which class(es) should be imported based on
052         * the {@link AnnotationMetadata} of the importing @{@link Configuration} class.
053         * @return the class names, or an empty array if none
054         */
055        String[] selectImports(AnnotationMetadata importingClassMetadata);
056
057}