org.polymap.core.runtime.SessionContext.java Source code

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Here is the source code for org.polymap.core.runtime.SessionContext.java

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/* 
 * polymap.org
 * Copyright 2011, Polymap GmbH. All rights reserved.
 *
 * This 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 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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.
 */
package org.polymap.core.runtime;

import java.util.concurrent.Callable;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Provides a unique API to the context of the session of the current thread. The
 * different front-end systems (RWT, GeoServer/OGC, WebDAV, etc.) can register a
 * specific {@link ISessionContextProvider}.
 * <p>
 * SessionContext also provides the API and SPI of the application context. This
 * interface is independent from HTTP/Servlet session context API.
 * 
 * @author <a href="http://www.polymap.de">Falko Brutigam</a>
 */
public abstract class SessionContext {

    private static Log log = LogFactory.getLog(SessionContext.class);

    private static ISessionContextProvider[] providers = {};

    public static void addProvider(ISessionContextProvider provider) {
        providers = (ISessionContextProvider[]) ArrayUtils.add(providers, provider);
    }

    public static void removeProvider(ISessionContextProvider provider) {
        providers = (ISessionContextProvider[]) ArrayUtils.removeElement(providers, provider);
    }

    public static final SessionContext current() {
        for (ISessionContextProvider provider : providers) {
            SessionContext context = provider.currentContext();
            if (context != null) {
                return context;
            }
        }
        return null;
    }

    // API ************************************************

    public abstract String getSessionKey();

    public abstract <T> T sessionSingleton(Class<T> type);

    /**
     * Executes the given Runnable inside this session context.
     * 
     * @param task The task to be executed. 
     */
    public abstract void execute(Runnable task);

    /**
     * Executes the given Callable inside this session context.
     * 
     * @param task The task to be executed. 
     */
    public abstract <T> T execute(final Callable<T> task) throws Exception;

    public abstract boolean addSessionListener(ISessionListener l);

    public abstract boolean removeSessionListener(ISessionListener l);

    /**
     * Binds an object to this session, using the name specified. If an object of the
     * same name is already bound to the session, the object is replaced.
     * 
     * @param string
     * @param value
     */
    public abstract void setAttribute(String key, Object value);

    public abstract Object getAttribute(String key);

    public abstract boolean isDestroyed();

}