org.eclipse.jetty.server.handler.ManagedAttributeListener Maven / Gradle / Ivy
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Ehcache is an open source, standards-based cache used to boost performance,
offload the database and simplify scalability. Ehcache is robust, proven and full-featured and
this has made it the most widely-used Java-based cache.
//
// ========================================================================
// Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.server.handler;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/* ------------------------------------------------------------ */
/** Enable Jetty style JMX MBeans from within a Context
*/
public class ManagedAttributeListener implements ServletContextListener, ServletContextAttributeListener
{
private static final Logger LOG = Log.getLogger(ManagedAttributeListener.class);
final Set _managedAttributes=new HashSet<>();
final ContextHandler _context;
public ManagedAttributeListener(ContextHandler context,String... managedAttributes)
{
_context=context;
for (String attr:managedAttributes)
_managedAttributes.add(attr);
if (LOG.isDebugEnabled())
LOG.debug("managedAttributes {}",_managedAttributes);
}
@Override
public void attributeReplaced(ServletContextAttributeEvent event)
{
if (_managedAttributes.contains(event.getName()))
updateBean(event.getName(),event.getValue(),event.getServletContext().getAttribute(event.getName()));
}
@Override
public void attributeRemoved(ServletContextAttributeEvent event)
{
if (_managedAttributes.contains(event.getName()))
updateBean(event.getName(),event.getValue(),null);
}
@Override
public void attributeAdded(ServletContextAttributeEvent event)
{
if (_managedAttributes.contains(event.getName()))
updateBean(event.getName(),null,event.getValue());
}
@Override
public void contextInitialized(ServletContextEvent event)
{
// Update existing attributes
Enumeration e = event.getServletContext().getAttributeNames();
while (e.hasMoreElements())
{
String name = e.nextElement();
if (_managedAttributes.contains(name))
updateBean(name,null,event.getServletContext().getAttribute(name));
}
}
@Override
public void contextDestroyed(ServletContextEvent event)
{
Enumeration e = _context.getServletContext().getAttributeNames();
while (e.hasMoreElements())
{
String name = e.nextElement();
if (_managedAttributes.contains(name))
updateBean(name,event.getServletContext().getAttribute(name),null);
}
}
protected void updateBean(String name,Object oldBean,Object newBean)
{
LOG.info("update {} {}->{} on {}",name,oldBean,newBean,_context);
if (LOG.isDebugEnabled())
LOG.debug("update {} {}->{} on {}",name,oldBean,newBean,_context);
_context.updateBean(oldBean,newBean,false);
}
}