org.springframework.integration.support.channel.BeanFactoryChannelResolver.java Source code

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Here is the source code for org.springframework.integration.support.channel.BeanFactoryChannelResolver.java

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/*
 * Copyright 2002-2019 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.integration.support.channel;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.integration.context.IntegrationContextUtils;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.core.DestinationResolutionException;
import org.springframework.messaging.core.DestinationResolver;
import org.springframework.util.Assert;

/**
 * {@link DestinationResolver} implementation based on a Spring {@link BeanFactory}.
 *
 * <p>Will lookup Spring managed beans identified by bean name,
 * expecting them to be of type {@link MessageChannel}.
 *
 * Consults a {@link HeaderChannelRegistry}, if available, if the bean is not found.
 *
 * @author Mark Fisher
 * @author Gary Russell
 * @author Artem Bilan
 *
 * @see org.springframework.beans.factory.BeanFactory
 */
public class BeanFactoryChannelResolver implements DestinationResolver<MessageChannel>, BeanFactoryAware {

    private static final Log logger = LogFactory.getLog(BeanFactoryChannelResolver.class);

    private BeanFactory beanFactory;

    private HeaderChannelRegistry replyChannelRegistry;

    private volatile boolean initialized;

    /**
     * Create a new instance of the {@link BeanFactoryChannelResolver} class.
     * <p>The BeanFactory to access must be set via <code>setBeanFactory</code>.
     * This will happen automatically if this resolver is defined within an
     * ApplicationContext thereby receiving the callback upon initialization.
     * @see #setBeanFactory
     */
    public BeanFactoryChannelResolver() {
    }

    /**
     * Create a new instance of the {@link BeanFactoryChannelResolver} class.
     * <p>Use of this constructor is redundant if this object is being created
     * by a Spring IoC container as the supplied {@link BeanFactory} will be
     * replaced by the {@link BeanFactory} that creates it (c.f. the
     * {@link BeanFactoryAware} contract). So only use this constructor if you
     * are instantiating this object explicitly rather than defining a bean.
     * @param beanFactory the bean factory to be used to lookup {@link MessageChannel}s.
     */
    public BeanFactoryChannelResolver(BeanFactory beanFactory) {
        Assert.notNull(beanFactory, "BeanFactory must not be null");
        this.beanFactory = beanFactory;
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
    }

    @Override
    public MessageChannel resolveDestination(String name) {
        Assert.state(this.beanFactory != null, "BeanFactory is required");
        try {
            return this.beanFactory.getBean(name, MessageChannel.class);
        } catch (BeansException e) {
            if (!(e instanceof NoSuchBeanDefinitionException)) {
                throw new DestinationResolutionException(
                        "A bean definition with name '" + name + "' exists, but failed to be created", e);
            }
            if (!this.initialized) {
                synchronized (this) {
                    if (!this.initialized) {
                        try {
                            this.replyChannelRegistry = this.beanFactory.getBean(
                                    IntegrationContextUtils.INTEGRATION_HEADER_CHANNEL_REGISTRY_BEAN_NAME,
                                    HeaderChannelRegistry.class);
                        } catch (Exception ex) {
                            logger.debug("No HeaderChannelRegistry found");
                        }
                        this.initialized = true;
                    }
                }
            }
            if (this.replyChannelRegistry != null) {
                MessageChannel channel = this.replyChannelRegistry.channelNameToChannel(name);
                if (channel != null) {
                    return channel;
                }
            }
            throw new DestinationResolutionException(
                    "failed to look up MessageChannel with name '" + name + "' in the BeanFactory"
                            + (this.replyChannelRegistry == null
                                    ? " (and there is no HeaderChannelRegistry present)."
                                    : "."),
                    e);
        }
    }

}