/*
* This file is part of FFMQ.
*
* FFMQ is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* FFMQ is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with FFMQ; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package net.timewalker.ffmq3.local.session;
import java.util.NoSuchElementException;
import javax.jms.JMSException;
import javax.jms.QueueBrowser;
import net.timewalker.ffmq3.common.message.AbstractMessage;
import net.timewalker.ffmq3.common.message.MessageSelector;
import net.timewalker.ffmq3.common.message.MessageTools;
import net.timewalker.ffmq3.common.session.AbstractQueueBrowserEnumeration;
import net.timewalker.ffmq3.local.destination.LocalQueue;
import net.timewalker.ffmq3.storage.message.MessageSerializationLevel;
/**
* <p>
* Implementation of a local {@link QueueBrowser} enumeration.
* Allows to browse messages in a local queue.
* </p>
* @see LocalQueueBrowser
*/
public final class LocalQueueBrowserEnumeration extends AbstractQueueBrowserEnumeration
{
private LocalQueue localQueue;
private MessageSelector parsedSelector;
private LocalQueueBrowserCursor cursor = new LocalQueueBrowserCursor();
// Runtime
private AbstractMessage nextMessage;
/**
* Constructor (package-private)
*/
protected LocalQueueBrowserEnumeration( LocalQueueBrowser browser , LocalQueue localQueue , MessageSelector parsedSelector , String enumId )
{
super(browser,enumId);
this.localQueue = localQueue;
this.parsedSelector = parsedSelector;
}
/**
* Fetch the next browsable message in the associated queue
* @return a message or null
* @throws JMSException on queue browsing error
*/
private AbstractMessage fetchNext() throws JMSException
{
if (nextMessage != null)
return nextMessage; // Already fetched
nextMessage = localQueue.browse(cursor, parsedSelector); // Lookup next candidate
if (nextMessage == null)
close(); // Auto-close enumeration at end of queue
return nextMessage;
}
/*
* (non-Javadoc)
* @see java.util.Enumeration#hasMoreElements()
*/
public boolean hasMoreElements()
{
if (cursor.endOfQueueReached())
return false;
try
{
checkNotClosed();
AbstractMessage msg = fetchNext();
return msg != null;
}
catch (JMSException e)
{
throw new IllegalStateException(e.toString());
}
}
/*
* (non-Javadoc)
* @see java.util.Enumeration#nextElement()
*/
public Object nextElement()
{
if (cursor.endOfQueueReached())
throw new NoSuchElementException();
try
{
checkNotClosed();
AbstractMessage msg = fetchNext();
if (msg != null)
{
nextMessage = null; // Consume fetched message
AbstractMessage msgCopy = MessageTools.duplicate(msg);
msgCopy.ensureDeserializationLevel(MessageSerializationLevel.FULL);
return msgCopy;
}
throw new NoSuchElementException();
}
catch (NoSuchElementException e)
{
throw e;
}
catch (JMSException e)
{
throw new IllegalStateException(e.toString());
}
}
}