ConfigurationPropertiesRebinderAutoConfiguration.java

/*
 * Copyright 2013-2015 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.cloud.autoconfigure;

import java.util.Collections;

import org.springframework.beans.factory.SmartInitializingSingleton;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.SearchStrategy;
import org.springframework.boot.context.properties.ConfigurationBeanFactoryMetaData;
import org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor;
import org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessorRegistrar;
import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
import org.springframework.cloud.context.properties.ConfigurationPropertiesBeans;
import org.springframework.cloud.context.properties.ConfigurationPropertiesRebinder;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConditionalOnBean(ConfigurationPropertiesBindingPostProcessor.class)
public class ConfigurationPropertiesRebinderAutoConfiguration
		implements ApplicationContextAware, SmartInitializingSingleton {

	private ApplicationContext context;

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) {
		this.context = applicationContext;
	}

	@Bean
	@ConditionalOnMissingBean(search = SearchStrategy.CURRENT)
	public ConfigurationPropertiesBeans configurationPropertiesBeans() {
		// Since this is a BeanPostProcessor we have to be super careful not to
		// cause a cascade of bean instantiation. Knowing the *name* of the beans we
		// need is super optimal, but a little brittle (unfortunately we have no
		// choice).
		ConfigurationBeanFactoryMetaData metaData = this.context.getBean(
				ConfigurationPropertiesBindingPostProcessorRegistrar.BINDER_BEAN_NAME
						+ ".store",
				ConfigurationBeanFactoryMetaData.class);
		ConfigurationPropertiesBeans beans = new ConfigurationPropertiesBeans();
		beans.setBeanMetaDataStore(metaData);
		return beans;
	}

	@Bean
	@ConditionalOnMissingBean(search = SearchStrategy.CURRENT)
	public ConfigurationPropertiesRebinder configurationPropertiesRebinder(
			ConfigurationPropertiesBeans beans,
			ConfigurationPropertiesBindingPostProcessor binder) {
		ConfigurationPropertiesRebinder rebinder = new ConfigurationPropertiesRebinder(
				binder, beans);
		return rebinder;
	}

	@Override
	public void afterSingletonsInstantiated() {
		// After all beans are initialized send a pre-emptive EnvironmentChangeEvent
		// so that anything that needs to rebind gets a chance now (especially for
		// beans in the parent context)
		this.context.publishEvent(
				new EnvironmentChangeEvent(Collections.<String> emptySet()));
	}
}