ConfigurationPropertiesRebinder.java

/*
 * Copyright 2013-2014 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.context.properties;

import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.aop.framework.Advised;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.BeansException;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationListener;
import org.springframework.core.env.Environment;
import org.springframework.jmx.export.annotation.ManagedAttribute;
import org.springframework.jmx.export.annotation.ManagedOperation;
import org.springframework.jmx.export.annotation.ManagedResource;
import org.springframework.stereotype.Component;

/**
 * Listens for {@link EnvironmentChangeEvent} and rebinds beans that were bound to the
 * {@link Environment} using {@link ConfigurationProperties
 * <code>@ConfigurationProperties</code>}. When these beans are re-bound and
 * re-initialized the changes are available immediately to any component that is using the
 * <code>@ConfigurationProperties</code> bean.
 *
 * @see RefreshScope for a deeper and optionally more focused refresh of bean components
 *
 * @author Dave Syer
 *
 */
@Component
@ManagedResource
public class ConfigurationPropertiesRebinder
		implements ApplicationContextAware, ApplicationListener<EnvironmentChangeEvent> {

	private ConfigurationPropertiesBeans beans;

	private ConfigurationPropertiesBindingPostProcessor binder;

	private ApplicationContext applicationContext;

	private Map<String, Exception> errors = new ConcurrentHashMap<>();

	public ConfigurationPropertiesRebinder(
			ConfigurationPropertiesBindingPostProcessor binder,
			ConfigurationPropertiesBeans beans) {
		this.binder = binder;
		this.beans = beans;
	}

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

	/**
	 * A map of bean name to errors when instantiating the bean.
	 *
	 * @return the errors accumulated since the latest destroy
	 */
	public Map<String, Exception> getErrors() {
		return this.errors;
	}

	@ManagedOperation
	public void rebind() {
		this.errors.clear();
		for (String name : this.beans.getBeanNames()) {
			rebind(name);
		}
	}

	@ManagedOperation
	public boolean rebind(String name) {
		if (!this.beans.getBeanNames().contains(name)) {
			return false;
		}
		if (this.applicationContext != null) {
			try {
				Object bean = this.applicationContext.getBean(name);
				if (AopUtils.isCglibProxy(bean)) {
					bean = getTargetObject(bean);
				}
				this.binder.postProcessBeforeInitialization(bean, name);
				this.applicationContext.getAutowireCapableBeanFactory()
						.initializeBean(bean, name);
				return true;
			}
			catch (RuntimeException e) {
				this.errors.put(name, e);
				throw e;
			}
		}
		return false;
	}

	@SuppressWarnings("unchecked")
	private static <T> T getTargetObject(Object candidate) {
		try {
			if (AopUtils.isAopProxy(candidate) && (candidate instanceof Advised)) {
				return (T) ((Advised) candidate).getTargetSource().getTarget();
			}
		}
		catch (Exception ex) {
			throw new IllegalStateException("Failed to unwrap proxied object", ex);
		}
		return (T) candidate;
	}

	@ManagedAttribute
	public Set<String> getBeanNames() {
		return new HashSet<String>(this.beans.getBeanNames());
	}

	@Override
	public void onApplicationEvent(EnvironmentChangeEvent event) {
		rebind();
	}

}