durableconsumerendpoint.java

一个java方面的消息订阅发送的源码

/**
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 *    please contact [e-mail].
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 * 5. Due credit should be given to the Exolab Project
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 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 *
 * Copyright 2001-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: DurableConsumerEndpoint.java,v 1.2 2005/03/18 03:58:39 tanderson Exp $
 */
package org.exolab.jms.messagemgr;

import java.sql.Connection;
import java.util.Iterator;
import java.util.List;
import javax.jms.InvalidSelectorException;
import javax.jms.JMSException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.exolab.jms.client.JmsTopic;
import org.exolab.jms.persistence.DatabaseService;
import org.exolab.jms.persistence.SQLHelper;
import org.exolab.jms.scheduler.Scheduler;
import org.exolab.jms.server.JmsServerSession;
import org.exolab.jms.server.JmsServerSession;


/**
 * A {@link ConsumerEndpoint} for durable topic consumers.
 * The state of durable topic consumers is maintained across server
 * invocations by the persistent layer.
 *
 * @author <a href="mailto:[e-mail]">Jim Alateras</a>
 * @author <a href="mailto:[e-mail]">Tim Anderson</a>
 * @version $Revision: 1.2 $ $Date: 2005/03/18 03:58:39 $
 */
public class DurableConsumerEndpoint
        extends AbstractTopicConsumerEndpoint {

    /**
     * The persistent name of the durable subscriber
     */
    private final String _name;

    /**
     * The logger
     */
    private static final Log _log
            = LogFactory.getLog(DurableConsumerEndpoint.class);

    /**
     * Create an durable consumer endpoint. This is a well-known endpoint which
     * can only be activated by one client at any one time.
     * <p/>
     * DurableConsumerEndpoints are always loaded in memory, whether they are
     * active or inactive. When they are inactive they simply process persistent
     * messages. Non-persistent message are ignored when the durable consumer is
     * inactive.
     *
     * @param consumerId the identity of this consumer
     * @param session    the owning session
     * @param topic      the topic to access
     * @param name       the well known name of the durable subscriber
     * @param selector   the message selector. May be <code>null</code>
     * @param noLocal    if true, inhibits the delivery of messages published by
     *                   its own connection.
     * @param scheduler  used to schedule asynchronous message delivery.
     * @throws InvalidSelectorException if the selector is invalid
     * @throws JMSException             if the destination caches can't be
     *                                  constructed
     */
    public DurableConsumerEndpoint(long consumerId, JmsServerSession session,
                                   JmsTopic topic, String name, String selector,
                                   boolean noLocal, Scheduler scheduler)
            throws InvalidSelectorException, JMSException {
        super(consumerId, session, topic, selector, noLocal, scheduler);
        _name = name;

        // call the persistence adapter to retrieve the state of this consumer
        Connection connection = null;
        try {
            connection = DatabaseService.getConnection();

            // remove expired messages
            DatabaseService.getAdapter().removeExpiredMessageHandles(
                    connection, _name);

            TopicDestinationCache cache = (TopicDestinationCache)
                    DestinationManager.instance().getDestinationCache(topic);
            // @todo - broken for wildcard subscriptions
            // getMessageHandles() needs to return all handles for a given
            // subscription name
            List handles = cache.getDurableMessageHandles(_name, connection);

            connection.commit();

            // iterate over each handle and add them to the list of messages
            // for the durable consumer
            Iterator iterator = handles.iterator();
            while (iterator.hasNext()) {
                MessageHandle handle = (MessageHandle) iterator.next();
                TopicConsumerMessageHandle consumer =
                        new TopicConsumerMessageHandle(handle, this);
                addMessage(consumer);
            }
        } catch (Exception exception) {
            SQLHelper.rollback(connection);
            String msg = "Failed to create durable consumer, name=" + name
                    + ", for topic=" + topic.getName();
            _log.error(msg, exception);
            throw new JMSException(msg + ": " + exception.getMessage());
        } finally {
            SQLHelper.close(connection);
        }

        init();
    }

    /**
     * Determines if this is a persistent or non-persistent consumer.
     * <p/>
     * If persistent, then the consumer is persistent accross subscriptions and
     * server restarts, and {@link #getPersistentId} returns a non-null value
     *
     * @return <code>true</code>
     */
    public boolean isPersistent() {
        return true;
    }

    /**
     * Returns the persistent identifier for this consumer.
     * <p/>
     * This is the identity of the consumer which is persistent across
     * subscriptions and server restarts.
     * <p/>
     * This implementation returns the consumer name.
     *
     * @return the persistent identifier for this consumer
     */
    public String getPersistentId() {
        return _name;
    }


}