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ActiveMQ example source code file (AbstractXMLMessageTransformer.java)

This example ActiveMQ source code file (AbstractXMLMessageTransformer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

abstractxmlmessagetransformer, adaptive, io, jmsexception, jmsexception, message, messageconsumer, messagetransform, object, object, objectmessage, objectmessage, textmessage, textmessage, xml

The ActiveMQ AbstractXMLMessageTransformer.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.activemq.util.oxm;

import java.io.Serializable;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.ObjectMessage;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.activemq.MessageTransformerSupport;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.HierarchicalStreamDriver;

/**
 * Abstract class used as a base for implementing transformers from object to text messages (in XML/JSON format)
 * and vice versa using.
 * Supports plugging of custom marshallers
 */
public abstract class AbstractXMLMessageTransformer extends
		MessageTransformerSupport {

    protected MessageTransform transformType;

    /**
     * Defines the type of transformation. If XML (default), - producer
     * transformation transforms from Object to XML. - consumer transformation
     * transforms from XML to Object. If OBJECT, - producer transformation
     * transforms from XML to Object. - consumer transformation transforms from
     * Object to XML. If ADAPTIVE, - producer transformation transforms from
     * Object to XML, or XML to Object depending on the type of the original
     * message - consumer transformation transforms from XML to Object, or
     * Object to XML depending on the type of the original message
     */
    public enum MessageTransform {
        XML, OBJECT, ADAPTIVE
    };


    public AbstractXMLMessageTransformer() {
        this(MessageTransform.XML);
    }

    public AbstractXMLMessageTransformer(MessageTransform transformType) {
        this.transformType = transformType;
    }

    public Message consumerTransform(Session session, MessageConsumer consumer, Message message) throws JMSException {
        switch (transformType) {
        case XML:
            return (message instanceof TextMessage) ? textToObject(session, (TextMessage)message) : message;
        case OBJECT:
            return (message instanceof ObjectMessage) ? objectToText(session, (ObjectMessage)message) : message;
        case ADAPTIVE:
            return (message instanceof TextMessage) ? textToObject(session, (TextMessage)message) : (message instanceof ObjectMessage) ? objectToText(session, (ObjectMessage)message) : message;
        default:
        }
        return message;
    }

    public Message producerTransform(Session session, MessageProducer producer, Message message) throws JMSException {
        switch (transformType) {
        case XML:
            return (message instanceof ObjectMessage) ? objectToText(session, (ObjectMessage)message) : message;
        case OBJECT:
            return (message instanceof TextMessage) ? textToObject(session, (TextMessage)message) : message;
        case ADAPTIVE:
            return (message instanceof TextMessage) ? textToObject(session, (TextMessage)message) : (message instanceof ObjectMessage) ? objectToText(session, (ObjectMessage)message) : message;
        default:
        }
        return message;
    }

    public MessageTransform getTransformType() {
        return transformType;
    }

    public void setTransformType(MessageTransform transformType) {
        this.transformType = transformType;
    }

    /**
     * Transforms an incoming XML encoded {@link TextMessage} to an
     * {@link ObjectMessage}
     * 
     * @param session - JMS session currently being used
     * @param textMessage - text message to transform to object message
     * @return ObjectMessage
     * @throws JMSException
     */
    protected ObjectMessage textToObject(Session session, TextMessage textMessage) throws JMSException {
        Object object = unmarshall(session, textMessage);
        if (object instanceof Serializable) {
            ObjectMessage answer = session.createObjectMessage((Serializable)object);
            copyProperties(textMessage, answer);
            return answer;
        } else {
            throw new JMSException("Object is not serializable: " + object);
        }
    }

    /**
     * Transforms an incoming {@link ObjectMessage} to an XML encoded
     * {@link TextMessage}
     * 
     * @param session - JMS session currently being used
     * @param objectMessage - object message to transform to text message
     * @return XML encoded TextMessage
     * @throws JMSException
     */
    protected TextMessage objectToText(Session session, ObjectMessage objectMessage) throws JMSException {
        TextMessage answer = session.createTextMessage(marshall(session, objectMessage));
        copyProperties(objectMessage, answer);
        return answer;
    }

    /**
     * Marshalls the Object in the {@link ObjectMessage} to a string using XML
     * encoding
     */
    protected abstract String marshall(Session session, ObjectMessage objectMessage) throws JMSException;

    /**
     * Unmarshalls the XML encoded message in the {@link TextMessage} to an
     * Object
     */
    protected abstract Object unmarshall(Session session, TextMessage textMessage) throws JMSException;

}

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