jdillon 2003/08/29 14:13:17
Added: modules/common/src/java/org/apache/geronimo/common/task
URLMonitorTask.java
Log:
o A timer task to monitor urls based on the last modified attribute
Revision Changes Path
1.1
incubator-geronimo/modules/common/src/java/org/apache/geronimo/common/task/URLMonitorTask.java
Index: URLMonitorTask.java
===================================================================
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" and
* "Apache Geronimo" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact [EMAIL PROTECTED]
*
* 5. Products derived from this software may not be called "Apache",
* "Apache Geronimo", nor may "Apache" appear in their name, without
* prior written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* ====================================================================
*/
package org.apache.geronimo.common.task;
import java.net.URL;
import java.net.URLConnection;
import java.util.Timer;
import java.util.TimerTask;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EventObject;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.geronimo.common.NullArgumentException;
/**
* A timer task to monitor a URL.
*
* @version $Revision: 1.1 $ $Date: 2003/08/29 21:13:16 $
*/
public class URLMonitorTask
extends TimerTask
{
private Log log = LogFactory.getLog(URLMonitorTask.class);
protected URL url;
private long lastChanged = -1;
protected List listeners = Collections.synchronizedList(new ArrayList());
public URLMonitorTask(final URL url)
{
if (url == null) {
throw new NullArgumentException("url");
}
this.url = url;
}
public URL getURL()
{
return url;
}
public long getLastChanged()
{
return lastChanged;
}
public void run()
{
log.trace("Checking if URL has changed");
boolean trace = log.isTraceEnabled();
try {
URLConnection connection = url.openConnection();
if (trace) {
log.trace("Connection: " + connection);
}
long lastModified = connection.getLastModified();
if (trace) {
log.trace("Last modified: " + lastModified + ", last changed:
" + lastChanged);
}
if (lastChanged < lastModified) {
fireURLChanged(new Event(this, lastModified));
lastChanged = lastModified;
}
}
catch (Exception e) {
log.warn("Failed to check URL: " + url, e);
}
}
/////////////////////////////////////////////////////////////////////////
// Listener Support //
/////////////////////////////////////////////////////////////////////////
public static class Event
extends EventObject
{
private URLMonitorTask task;
private long lastModified;
Event(final URLMonitorTask task, final long lastModified)
{
super(task);
assert task != null;
this.task = task;
this.lastModified = lastModified;
}
public URLMonitorTask getURLMonitorTask()
{
return task;
}
public URL getURL()
{
return getURLMonitorTask().getURL();
}
public long getLastModified()
{
return lastModified;
}
}
public static interface Listener
{
void doURLChanged(Event event);
}
public void addListener(final Listener listener) {
if (listener == null) {
throw new NullArgumentException("listener");
}
// only add the listener if it isn't already in the list
if (!listeners.contains(listener)) {
listeners.add(listener);
}
}
public void removeThrowableListener(final Listener listener) {
if (listener == null) {
throw new NullArgumentException("listener");
}
listeners.remove(listener);
}
protected void fireURLChanged(final Event event) {
assert event != null;
Object[] list = listeners.toArray();
for (int i=0; i<list.length; i++) {
Listener listener = (Listener)list[i];
assert listener != null;
listener.doURLChanged(event);
}
}
}
