trunk/core/src/main/java/org/apache/struts2/config/ServletContextSingleton.java

/*
 * $Id$
 *
 * Copyright 2006 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.struts2.config;

import javax.servlet.ServletContext;

/**
 * This singleton holds an instance of the web servlet context.
 * <p/>
 * This is needed for running Struts on Weblogic Server 6.1
 * because there is no provision to retrieve the servlet context
 * from the web session object.
 * <p/>
 * This class is created to bet that this singleton can be set by
 * {@link org.apache.struts2.dispatcher.FilterDispatcherCompatWeblogic61}
 * before the servlet context is needed by
 * {@link org.apache.struts2.lifecycle.SessionLifecycleListener}
 * which will use this object to get it.
 *
 */
public class ServletContextSingleton {
    /**
     * The web servlet context.  Holding this is the
     * purpose of this singleton.
     */
    private ServletContext servletContext;

    /**
     * The sole instance of this class.
     */
    private static ServletContextSingleton singleton;

    /**
     * Constructor which cannot be called
     * publicly.
     */
    private ServletContextSingleton() {
    }

    /**
     * Answers the singleton.
     * <p/>
     * At some point, the caller must populate the web servlet
     * context.
     *
     * @return Answers the singleton instance of this class
     */
    public static ServletContextSingleton getInstance() {
        if (singleton == null) {
            singleton = new ServletContextSingleton();
        }
        return singleton;
    }

    /**
     * Gets the servlet context
     * 
     * @return The web servlet context
     */
    public ServletContext getServletContext() {
        return servletContext;
    }

    /**
     * Sets the servlet context
     * 
     * @param context The web servlet context
     */
    public void setServletContext(ServletContext context) {
        servletContext = context;
    }

}