/*
* Copyright 2002-2016 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.integration.aggregator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
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.integration.IntegrationMessageHeaderAccessor;
import org.springframework.integration.store.MessageGroup;
import org.springframework.integration.support.AbstractIntegrationMessageBuilder;
import org.springframework.integration.support.DefaultMessageBuilderFactory;
import org.springframework.integration.support.MessageBuilderFactory;
import org.springframework.integration.support.utils.IntegrationUtils;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
/**
* Base class for MessageGroupProcessor implementations that aggregate the group of Messages into a single Message.
*
* @author Iwein Fuld
* @author Alexander Peters
* @author Mark Fisher
* @author Dave Syer
* @author Gary Russell
* @author Artem Bilan
*
* @since 2.0
*/
public abstract class AbstractAggregatingMessageGroupProcessor implements MessageGroupProcessor,
BeanFactoryAware {
private final Log logger = LogFactory.getLog(this.getClass());
private volatile MessageBuilderFactory messageBuilderFactory = new DefaultMessageBuilderFactory();
private volatile boolean messageBuilderFactorySet;
private BeanFactory beanFactory;
@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.beanFactory = beanFactory;
}
protected MessageBuilderFactory getMessageBuilderFactory() {
if (!this.messageBuilderFactorySet) {
if (this.beanFactory != null) {
this.messageBuilderFactory = IntegrationUtils.getMessageBuilderFactory(this.beanFactory);
}
this.messageBuilderFactorySet = true;
}
return this.messageBuilderFactory;
}
@Override
public final Object processMessageGroup(MessageGroup group) {
Assert.notNull(group, "MessageGroup must not be null");
Map<String, Object> headers = this.aggregateHeaders(group);
Object payload = this.aggregatePayloads(group, headers);
AbstractIntegrationMessageBuilder<?> builder;
if (payload instanceof Message<?>) {
builder = getMessageBuilderFactory().fromMessage((Message<?>) payload);
}
else if (payload instanceof AbstractIntegrationMessageBuilder) {
builder = (AbstractIntegrationMessageBuilder<?>) payload;
}
else {
builder = getMessageBuilderFactory().withPayload(payload);
}
return builder.copyHeadersIfAbsent(headers)
.popSequenceDetails()
.build();
}
/**
* This default implementation simply returns all headers that have no conflicts among the group. An absent header
* on one or more Messages within the group is not considered a conflict. Subclasses may override this method with
* more advanced conflict-resolution strategies if necessary.
*
* @param group The message group.
* @return The aggregated headers.
*/
protected Map<String, Object> aggregateHeaders(MessageGroup group) {
Map<String, Object> aggregatedHeaders = new HashMap<String, Object>();
Set<String> conflictKeys = new HashSet<String>();
for (Message<?> message : group.getMessages()) {
for (Entry<String, Object> entry : message.getHeaders().entrySet()) {
String key = entry.getKey();
if (MessageHeaders.ID.equals(key) || MessageHeaders.TIMESTAMP.equals(key)
|| IntegrationMessageHeaderAccessor.SEQUENCE_SIZE.equals(key)
|| IntegrationMessageHeaderAccessor.SEQUENCE_NUMBER.equals(key)) {
continue;
}
Object value = entry.getValue();
if (!aggregatedHeaders.containsKey(key)) {
aggregatedHeaders.put(key, value);
}
else {
Object existingValue = aggregatedHeaders.get(key);
if (value != existingValue && (value == null || !value.equals(existingValue))) {
conflictKeys.add(key);
}
}
}
}
for (String keyToRemove : conflictKeys) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Excluding header '" + keyToRemove + "' upon aggregation due to conflict(s) "
+ "in MessageGroup with correlation key: " + group.getGroupId());
}
aggregatedHeaders.remove(keyToRemove);
}
return aggregatedHeaders;
}
protected abstract Object aggregatePayloads(MessageGroup group, Map<String, Object> defaultHeaders);
}