ApplicationContextAwareProcessor.java

/*
 * Copyright 2002-2010 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
 *
 *      http://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.ConfigurableBeanFactory;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.EmbeddedValueResolverAware;
import org.springframework.context.MessageSourceAware;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.util.StringValueResolver;

/**
 * {@link org.springframework.beans.factory.config.BeanPostProcessor}
 * implementation that passes the ApplicationContext to beans that
 * implement the {@link ResourceLoaderAware}, {@link MessageSourceAware},
 * {@link ApplicationEventPublisherAware} and/or
 * {@link ApplicationContextAware} interfaces.
 * If all of them are implemented, they are satisfied in the given order.
 *
 * <p>Application contexts will automatically register this with their
 * underlying bean factory. Applications do not use this directly.
 *
 * @author Juergen Hoeller
 * @author Costin Leau
 * @since 10.10.2003
 * @see org.springframework.context.ResourceLoaderAware
 * @see org.springframework.context.MessageSourceAware
 * @see org.springframework.context.ApplicationEventPublisherAware
 * @see org.springframework.context.ApplicationContextAware
 * @see org.springframework.context.support.AbstractApplicationContext#refresh()
 */
class ApplicationContextAwareProcessor implements BeanPostProcessor {

	private final ConfigurableApplicationContext applicationContext;


	/**
	 * Create a new ApplicationContextAwareProcessor for the given context.
	 */
	public ApplicationContextAwareProcessor(ConfigurableApplicationContext applicationContext) {
		this.applicationContext = applicationContext;
	}


	public Object postProcessBeforeInitialization(final Object bean, String beanName) throws BeansException {
		AccessControlContext acc = null;

		if (System.getSecurityManager() != null &&
				(bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||
						bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware)) {
			acc = this.applicationContext.getBeanFactory().getAccessControlContext();
		}

		if (acc != null) {
			AccessController.doPrivileged(new PrivilegedAction<Object>() {
				public Object run() {
					invokeAwareInterfaces(bean);
					return null;
				}
			}, acc);
		}
		else {
			invokeAwareInterfaces(bean);
		}
		
		return bean;
	}
	
	private void invokeAwareInterfaces(Object bean) {
		if (bean instanceof EmbeddedValueResolverAware) {
			((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(
					new EmbeddedValueResolver(this.applicationContext.getBeanFactory()));
		}
		if (bean instanceof ResourceLoaderAware) {
			((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
		}
		if (bean instanceof ApplicationEventPublisherAware) {
			((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
		}
		if (bean instanceof MessageSourceAware) {
			((MessageSourceAware) bean).setMessageSource(this.applicationContext);
		}
		if (bean instanceof ApplicationContextAware) {
			((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
		}
	}

	public Object postProcessAfterInitialization(Object bean, String beanName) {
		return bean;
	}


	private static class EmbeddedValueResolver implements StringValueResolver {

		private final ConfigurableBeanFactory beanFactory;

		public EmbeddedValueResolver(ConfigurableBeanFactory beanFactory) {
			this.beanFactory = beanFactory;
		}

		public String resolveStringValue(String strVal) {
			return this.beanFactory.resolveEmbeddedValue(strVal);
		}
	}

}