文章目录

• Pre
• org.springframework.context.support.ApplicationContextAwareProcessor
• 内部的7个扩展点
• 源码解析
• 扩展示例

Pre

Spring Boot - 扩展接口一览

org.springframework.context.support.ApplicationContextAwareProcessor

/** Copyright 2002-2020 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**      https://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.context.support;import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.EmbeddedValueResolver;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.context.ApplicationStartupAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.EmbeddedValueResolverAware;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.MessageSourceAware;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.lang.Nullable;
import org.springframework.util.StringValueResolver;/*** {@link BeanPostProcessor} implementation that supplies the {@code ApplicationContext},* {@link org.springframework.core.env.Environment Environment}, or* {@link StringValueResolver} for the {@code ApplicationContext} to beans that* implement the {@link EnvironmentAware}, {@link EmbeddedValueResolverAware},* {@link ResourceLoaderAware}, {@link ApplicationEventPublisherAware},* {@link MessageSourceAware}, and/or {@link ApplicationContextAware} interfaces.** 
Implemented interfaces are satisfied in the order in which they are* mentioned above.** 
Application contexts will automatically register this with their* underlying bean factory. Applications do not use this directly.** @author Juergen Hoeller* @author Costin Leau* @author Chris Beams* @since 10.10.2003* @see org.springframework.context.EnvironmentAware* @see org.springframework.context.EmbeddedValueResolverAware* @see org.springframework.context.ResourceLoaderAware* @see org.springframework.context.ApplicationEventPublisherAware* @see org.springframework.context.MessageSourceAware* @see org.springframework.context.ApplicationContextAware* @see org.springframework.context.support.AbstractApplicationContext#refresh()*/
class ApplicationContextAwareProcessor implements BeanPostProcessor {private final ConfigurableApplicationContext applicationContext;private final StringValueResolver embeddedValueResolver;/*** Create a new ApplicationContextAwareProcessor for the given context.*/public ApplicationContextAwareProcessor(ConfigurableApplicationContext applicationContext) {this.applicationContext = applicationContext;this.embeddedValueResolver = new EmbeddedValueResolver(applicationContext.getBeanFactory());}@Override@Nullablepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {if (!(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware ||bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware ||bean instanceof ApplicationStartupAware)) {return bean;}AccessControlContext acc = null;if (System.getSecurityManager() != null) {acc = this.applicationContext.getBeanFactory().getAccessControlContext();}if (acc != null) {AccessController.doPrivileged((PrivilegedAction