trunk/activemq-optional/src/main/java/org/apache/activemq/util/xstream/XStreamMessageTransformer.java

/**
 * 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.xstream;

import java.io.Serializable;
import java.io.StringReader;
import java.io.StringWriter;

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;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.xml.PrettyPrintWriter;
import com.thoughtworks.xstream.io.xml.XppReader;

/**
 * Transforms object messages to text messages and vice versa using
 * {@link XStream}
 * 
 * @deprecated as of 5.3.0 release replaced by {@link org.apache.activemq.util.oxm.XStreamMessageTransformer}
 * 
 * 
 */
@Deprecated
public class XStreamMessageTransformer extends MessageTransformerSupport {

    protected MessageTransform transformType;
    private XStream xStream;
    
    /**
     * Specialized driver to be used with stream readers and writers
     */
    private HierarchicalStreamDriver streamDriver;

    /**
     * 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 XStreamMessageTransformer() {
        this(MessageTransform.XML);
    }

    public XStreamMessageTransformer(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;
    }

    // Properties
    // -------------------------------------------------------------------------
    public XStream getXStream() {
        if (xStream == null) {
            xStream = createXStream();
        }
        return xStream;
    }

    public void setXStream(XStream xStream) {
        this.xStream = xStream;
    }

    public HierarchicalStreamDriver getStreamDriver() {
		return streamDriver;
    }

	public void setStreamDriver(HierarchicalStreamDriver streamDriver) {
		this.streamDriver = streamDriver;
    }

	// Implementation methods
    // -------------------------------------------------------------------------
    protected XStream createXStream() {
        return new XStream();
    }

    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 String marshall(Session session, ObjectMessage objectMessage) throws JMSException {
        Serializable object = objectMessage.getObject();
        StringWriter buffer = new StringWriter();
        HierarchicalStreamWriter out;
        if (streamDriver != null) {
        	out = streamDriver.createWriter(buffer);
        } else {
        	out = new PrettyPrintWriter(buffer);
        }
        getXStream().marshal(object, out);
        return buffer.toString();
    }

    /**
     * Unmarshalls the XML encoded message in the {@link TextMessage} to an
     * Object
     */
    protected Object unmarshall(Session session, TextMessage textMessage) throws JMSException {
        HierarchicalStreamReader in;
        if (streamDriver != null) {
        	in = streamDriver.createReader(new StringReader(textMessage.getText()));
        } else {
        	in = new XppReader(new StringReader(textMessage.getText()));
        }
        return getXStream().unmarshal(in);
    }

}