2009/05/20 - Apache Shale has been retired.

 /*

  * 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.

  */

 package org.apache.shale.dialog.base;

 import java.util.ArrayList;

 import java.util.List;

 import javax.faces.context.FacesContext;

 import javax.servlet.http.HttpSessionBindingEvent;

 import javax.servlet.http.HttpSessionBindingListener;

 import org.apache.shale.dialog.Constants;

 import org.apache.shale.dialog.DialogContext;

 import org.apache.shale.dialog.DialogContextManager;

 import org.apache.shale.dialog.DialogContextManagerListener;

 import org.apache.shale.dialog.DialogLifecycleListener;

 /**

  * <p>Abstract base class for {@link DialogContextManager} implementations.

  * Provides listener registration and event firing convenience methods.

  * Subclasses are expected to be serializable.</p>

  *

  * @since 1.0.4

  */

 public abstract class AbstractDialogContextManager

   implements DialogContextManager, HttpSessionBindingListener {

     // ------------------------------------------------------ Instance Variables

     /**

      * <p><code>List</code> of registered {@link DialogContextManagerListener}

      * instances.</p>

      */

     private List listeners = new ArrayList();

     // -------------------------------------- HttpSessionBindingListener Methods

     /**

      * <p>Handle an instance of this class being bound into an HttpSession.</p>

      *

      * @param event HttpSessionBindingEvent to be handled

      */

     public void valueBound(HttpSessionBindingEvent event) {

         DialogLifecycleListener listener = lifecycleListener();

         if (listener != null) {

             listener.onInit(this);

         }

     }

     /**

      * <p>Handle an instance of this class being unbound from an HttpSession.</p>

      *

      * @param event HttpSessionBindingEvent to be handled

      */

     public void valueUnbound(HttpSessionBindingEvent event) {

         DialogLifecycleListener listener = lifecycleListener();

         if (listener != null) {

             listener.onDestroy(this);

         }

     }

     // --------------------------------------------------- Listener Registration

     /**

      * <p>Register a new {@link DialogContextManagerListener} instance.</p>

      *

      * @param listener The new listener instance to be registered

      */

     public void addDialogContextManagerListener(DialogContextManagerListener listener) {

         if (listener == null) {

             throw new IllegalArgumentException("Cannot register null DialogContextManagerListener");

         }

         synchronized (listeners) {

             if (listeners.contains(listener)) {

                 throw new IllegalArgumentException("DialogContextManagerListener already registered");

             }

             listener.setDialogContextManager(this); // attach self reference

             listeners.add(listener);

         }

     }

     /**

      * <p>Return the set of currently registered {@link DialogContextManagerListener}s.

      * If there are no registered listeners, a zero-length array is returned.</p>

      */

     public DialogContextManagerListener[] getDialogContextManagerListeners() {

         synchronized (listeners) {

             return (DialogContextManagerListener[])

               listeners.toArray(new DialogContextManagerListener[listeners.size()]);

         }

     }

     /**

      * <p>Deregister an existing {@link DialogContextManagerListener} instance.</p>

      *

      * @param listener The existing listener to be deregistered

      */

     public void removeDialogContextManagerListener(DialogContextManagerListener listener) {

         if (listener == null) {

             throw new IllegalArgumentException("Cannot remove null DialogContextManagerListener");

         }

         boolean removed;

         synchronized (listeners) {

             removed = listeners.remove(listener);

         }

         if (removed) {

             listener.setDialogContextManager(null); // detach self reference

         }

     }

     // ---------------------------------------------------- Event Firing Methods

     /**

      * <p>Fire an <code>onCreate()</code> event to all registered listeners.</p>

      *

      * @param context The {@link DialogContext} instance that has been created

      */

     protected void fireOnCreate(DialogContext context) {

         DialogContextManagerListener[] listeners =

           getDialogContextManagerListeners();

         for (int i = 0; i < listeners.length; i++) {

             listeners[i].onCreate(context);

         }

     }

     /**

      * <p>Fire an <code>onRemove()</code> event to all registered listeners.</p>

      *

      * @param context The {@link DialogContext} instance that has been removed

      */

     protected void fireOnRemove(DialogContext context) {

         DialogContextManagerListener[] listeners =

           getDialogContextManagerListeners();

         for (int i = 0; i < listeners.length; i++) {

             listeners[i].onRemove(context);

         }

     }

     // --------------------------------------------------------- Private Methods

     /**

      * <p>Return the {@link DialogLifecycleListener} for this application

      * (if any); otherwise, return <code>null</code>.</p>

      */

     private DialogLifecycleListener lifecycleListener() {

         FacesContext context = FacesContext.getCurrentInstance();

         if (context == null) {

             return null;

         }

         Object result =

           context.getApplication().getVariableResolver().

           resolveVariable(context, Constants.LIFECYCLE_ATTR);

         if ((result != null) && (result instanceof DialogLifecycleListener)) {

             return (DialogLifecycleListener) result;

         } else {

             return null;

         }

     }

 }