Glassfish example source code file (SessionTracker.java)

This example Glassfish source code file (SessionTracker.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Glassfish tags/keywords

arraylist, arraylist, illegalargumentexception, response, response, session, session, sessionlistener, sessiontracker, should, string, string, util

The Glassfish SessionTracker.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 *
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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.
 */

package org.apache.catalina.connector;

import org.apache.catalina.Session;
import org.apache.catalina.SessionEvent;
import org.apache.catalina.SessionListener;

import java.util.ArrayList;

/**
 * Class responsible for keeping track of the total number of active sessions
 * associated with an HTTP request.
 *
 * <p>A given HTTP request may be associated with more than one active
 * session if it has been dispatched to one or more foreign contexts.
 *
 * <p>The number of active sessions being tracked is used to determine whether
 * or not any session information needs to be reflected in the response (e.g.,
 * in the form of a response cookie). If no active sessions are associated
 * with the request by the time the response is committed, no session
 * information will be reflected in the response.
 *
 * See GlassFish Issue 896 for additional details.
 */
public class SessionTracker implements SessionListener {

    // The number of currently tracked sessions
    private int count;

    // The session id that is shared by all tracked sessions
    private String trackedSessionId;

    private Response response;

    /*
     * The list of contexts whose sessions we're tracking.
     *
     * The size of this list will be greater than one only in cross
     * context request dispatch scenarios
     */
    private ArrayList contextNames = new ArrayList(2);

    /**
     * Processes the given session event, by unregistering this SessionTracker
     * as a session listener from the session that is the source of the event,
     * and by decrementing the counter of currently tracked sessions.
     *
     * @param event The session event
     */
    public void sessionEvent(SessionEvent event) {

        if (!Session.SESSION_DESTROYED_EVENT.equals(event.getType())) {
            return;
        }

        Session session = event.getSession();

        synchronized (this) {
            if (session.getIdInternal() != null
                    && session.getIdInternal().equals(trackedSessionId)
                    && session.getManager() != null
                    && session.getManager().getContainer() != null
                    && contextNames.contains(
                            session.getManager().getContainer().getName())) {
                count--;
                if (count == 0) {
                    trackedSessionId = null;
                    if (response != null) {
                        response.removeSessionCookies();
                    }
                }
            }

            session.removeSessionListener(this);
        }
    }

    /**
     * Gets the number of active sessions that are being tracked.
     *
     * @return The number of active sessions being tracked
     */
    public int getActiveSessions() {
        return count;
    }

    /**
     * Gets the id of the sessions that are being tracked.
     *
     * Notice that since all sessions are associated with the same request,
     * albeit in different context, they all share the same id.
     *
     * @return The id of the sessions that are being tracked
     */
    public String getSessionId() {
        return trackedSessionId;
    }

    /**
     * Tracks the given session, by registering this SessionTracker as a
     * listener with the given session, and by incrementing the counter of
     * currently tracked sessions.
     *
     * @param session The session to track
     */
    public synchronized void track(Session session) {

        if (trackedSessionId == null) {
            trackedSessionId = session.getIdInternal();
        } else if (!trackedSessionId.equals(session.getIdInternal())) {
            throw new IllegalArgumentException("Should never reach here");
        }

        count++;

        if (session.getManager() != null
                && session.getManager().getContainer() != null
                && session.getManager().getContainer().getName() != null) {
            contextNames.add(session.getManager().getContainer().getName());
        }

        session.addSessionListener(this);
    }

    /**
     * Associates the given response with this SessionTracker.
     *
     * If the number of tracked sessions drops to zero, this SessionTracker
     * will remove the Set-Cookie from the given response.
     *
     * @param response The response from which to remove the Set-Cookie
     * header if the number of tracked sessions drops to zero
     */
    public synchronized void setResponse(Response response) {
        this.response = response;
    }

    /**
     * Resets this session tracker.
     */
    public synchronized void reset() {
        count = 0;
        trackedSessionId = null;
        contextNames.clear();
    }

}