AbstractMessageListener.java

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 * Copyright 2011, Red Hat, Inc. and/or its affiliates, and individual
 * contributors by the @authors tag. See the copyright.txt in the
 * distribution for a full listing of individual contributors.
 *
 * 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.jboss.seam.jms;

import javax.enterprise.inject.spi.BeanManager;
import javax.jms.JMSException;
import javax.jms.Message;

import org.jboss.solder.logging.Logger;

/**
 * Supporting base MessageListener for working in CDI enabled environments.
 * This is useful for having a MessageListener
 *
 * @author johnament
 */
public abstract class AbstractMessageListener implements javax.jms.MessageListener {

    private Logger logger;
    protected BeanManager beanManager;
    protected ClassLoader classLoader;

    protected AbstractMessageListener() {
        this.logger = Logger.getLogger(AbstractMessageListener.class);
    }

    protected AbstractMessageListener(BeanManager beanManager, ClassLoader classLoader) {
        this();
        this.beanManager = beanManager;
        this.classLoader = classLoader;
        logger.debug("Creating new AbstractMessageListener.");
    }

    protected void setBeanManager(BeanManager beanManager) {
        this.beanManager = beanManager;
    }

    protected void setClassLoader(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }

    /**
     * AbstractMessageListener implements the basic on message functionality to
     * handle classloader behavior for working in CDI environments.
     * <p/>
     * This method should not be overridden, even though it is not final.
     *
     * @param message The JMS Message that is being received.
     */
    public void onMessage(Message message) {
        logger.info("Received a message");
        ClassLoader prevCl = Thread.currentThread().getContextClassLoader();
        Thread.currentThread().setContextClassLoader(classLoader);
        try {
            handleMessage(message);
        } catch (JMSException e) {
            logger.warn("A JMS Exception occurred during processing.", e);
        } finally {
            Thread.currentThread().setContextClassLoader(prevCl);
        }
    }

    /**
     * Implementations should override this method and
     * perform necessary business logic in here.
     * <p/>
     * A BeanManager reference is available, for looking up beans.
     *
     * @param message The message to be handled.
     * @throws JMSException The method can throw this exception if an error occurred.
     */
    protected abstract void handleMessage(Message message) throws JMSException;
}