/*
* Copyright 2002-2014 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.integration.transformer;
import org.springframework.integration.context.IntegrationObjectSupport;
import org.springframework.messaging.Message;
/**
* A base class for {@link Transformer} implementations.
*
* @author Mark Fisher
* @author Oleg Zhurakousky
*/
public abstract class AbstractTransformer extends IntegrationObjectSupport implements Transformer {
@Override
public final Message<?> transform(Message<?> message) {
try {
Object result = this.doTransform(message);
if (result == null) {
return null;
}
return (result instanceof Message) ? (Message<?>) result
: this.getMessageBuilderFactory().withPayload(result).copyHeaders(message.getHeaders()).build();
}
catch (MessageTransformationException e) {
throw e;
}
catch (Exception e) {
throw new MessageTransformationException(message, "failed to transform message", e);
}
}
/**
* Subclasses must implement this method to provide the transformation
* logic. If the return value is itself a Message, it will be used as the
* result. Otherwise, any non-null return value will be used as the payload
* of the result Message.
*
* @param message The message.
* @return The result of the transformation.
* @throws Exception Any exception.
*/
protected abstract Object doTransform(Message<?> message) throws Exception;
}