Mega Code Archive
Servlet HttpSessionListener
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
/**
* Example listener for context-related application events, which were
* introduced in the 2.3 version of the Servlet API. This listener
* merely documents the occurrence of such events in the application log
* associated with our servlet context.
*
* @author Craig R. McClanahan
* @version $Revision: 466607 $ $Date: 2006-10-21 17:09:50 -0600 (Sat, 21 Oct 2006) $
*/
public final class MyServlet
implements ServletContextListener,
HttpSessionAttributeListener, HttpSessionListener {
// ----------------------------------------------------- Instance Variables
/**
* The servlet context with which we are associated.
*/
private ServletContext context = null;
// --------------------------------------------------------- Public Methods
/**
* Record the fact that a servlet context attribute was added.
*
* @param event The session attribute event
*/
public void attributeAdded(HttpSessionBindingEvent event) {
log("attributeAdded('" + event.getSession().getId() + "', '" +
event.getName() + "', '" + event.getValue() + "')");
}
/**
* Record the fact that a servlet context attribute was removed.
*
* @param event The session attribute event
*/
public void attributeRemoved(HttpSessionBindingEvent event) {
log("attributeRemoved('" + event.getSession().getId() + "', '" +
event.getName() + "', '" + event.getValue() + "')");
}
/**
* Record the fact that a servlet context attribute was replaced.
*
* @param event The session attribute event
*/
public void attributeReplaced(HttpSessionBindingEvent event) {
log("attributeReplaced('" + event.getSession().getId() + "', '" +
event.getName() + "', '" + event.getValue() + "')");
}
/**
* Record the fact that this web application has been destroyed.
*
* @param event The servlet context event
*/
public void contextDestroyed(ServletContextEvent event) {
log("contextDestroyed()");
this.context = null;
}
/**
* Record the fact that this web application has been initialized.
*
* @param event The servlet context event
*/
public void contextInitialized(ServletContextEvent event) {
this.context = event.getServletContext();
log("contextInitialized()");
}
/**
* Record the fact that a session has been created.
*
* @param event The session event
*/
public void sessionCreated(HttpSessionEvent event) {
log("sessionCreated('" + event.getSession().getId() + "')");
}
/**
* Record the fact that a session has been destroyed.
*
* @param event The session event
*/
public void sessionDestroyed(HttpSessionEvent event) {
log("sessionDestroyed('" + event.getSession().getId() + "')");
}
// -------------------------------------------------------- Private Methods
/**
* Log a message to the servlet context application log.
*
* @param message Message to be logged
*/
private void log(String message) {
if (context != null)
context.log("SessionListener: " + message);
else
System.out.println("SessionListener: " + message);
}
/**
* Log a message and associated exception to the servlet context
* application log.
*
* @param message Message to be logged
* @param throwable Exception to be logged
*/
private void log(String message, Throwable throwable) {
if (context != null)
context.log("SessionListener: " + message, throwable);
else {
System.out.println("SessionListener: " + message);
throwable.printStackTrace(System.out);
}
}
}
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<listener>
<listener-class>MyServlet</listener-class>
</listener>
</web-app>
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