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.view.faces;

 import java.util.ArrayList;

 import java.util.Enumeration;

 import java.util.Iterator;

 import java.util.List;

 import javax.faces.context.FacesContext;

 import javax.servlet.ServletContextAttributeEvent;

 import javax.servlet.ServletContextAttributeListener;

 import javax.servlet.ServletContextEvent;

 import javax.servlet.ServletContextListener;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletRequestAttributeEvent;

 import javax.servlet.ServletRequestAttributeListener;

 import javax.servlet.ServletRequestEvent;

 import javax.servlet.ServletRequestListener;

 import javax.servlet.http.HttpSessionActivationListener;

 import javax.servlet.http.HttpSessionAttributeListener;

 import javax.servlet.http.HttpSessionBindingEvent;

 import javax.servlet.http.HttpSessionEvent;

 import javax.servlet.http.HttpSessionListener;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.shale.view.AbstractApplicationBean;

 import org.apache.shale.view.AbstractRequestBean;

 import org.apache.shale.view.AbstractSessionBean;

 import org.apache.shale.view.Constants;

 import org.apache.shale.view.ExceptionHandler;

 import org.apache.shale.view.ViewController;

 /**

  * <p><strong>LifecycleListener</strong> implements the lifecycle startup

  * and shutdown calls (<code>init()</code> and <code>destroy()</code>) for

  * subclasses of {@link AbstractApplicationBean}, {@link AbstractRequestBean},

  * and {@link AbstractSessionBean}.</p>

  *

  * <p>It must be registered with the servlet container as a listener,

  * through an entry in either the <code>/WEB-INF/web.xml</code> resource

  * or a tag library descriptor included in the web application.</p>

  *

  * $Id: LifecycleListener.java 464373 2006-10-16 04:21:54Z rahul $

  *

  * @since 1.0.3

  */

 public class LifecycleListener

     implements ServletContextAttributeListener,

                ServletContextListener,

                HttpSessionActivationListener,

                HttpSessionAttributeListener,

                HttpSessionListener,

                ServletRequestAttributeListener,

                ServletRequestListener {

     // ------------------------------------------------------------- Constructor

     /**

      * <p>Create a new lifecycle listener.</p>

      */

     public LifecycleListener() {

         if (log.isInfoEnabled()) {

             log.info("Initializing org.apache.shale.view.faces.LifecycleListener");

         }

     }

     // -------------------------------------------------------- Static Variables

     /**

      * <p>The <code>Log</code> instance for this class.</p>

      */

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

     // ------------------------------------------------------ Manifest Constants

     /**

      * <p>The fully qualified class name of the <em>Tiger Extensions</em>

      * verison of this listener class.</p>

      */

     private static final String TIGER_LISTENER =

             "org.apache.shale.tiger.view.faces.LifecycleListener2";

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

     /**

      * <p>The <em>Tiger Extensions</em> implementation of this listener, if

      * such a class exists in the application classpath.  This value is lazily

      * instantiated.</p>

      */

     private LifecycleListener tiger = null;

     /**

      * <p>Flag indicating whether the <code>tiger</code> value has been calculated

      * already.</p>

      */

     private boolean tigerInitialized = false;

     // ------------------------------------------ ServletContextListener Methods

     /**

      * <p>Respond to a context created event.  No special processing

      * is required.</p>

      *

      * @param event Event to be processed

      */

     public void contextInitialized(ServletContextEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.contextInitialized(event);

         }

     }

     /**

      * <p>Respond to a context destroyed event.  Causes any application

      * scope attribute that implements {@link AbstractApplicationBean}

      * to be removed, triggering an <code>attributeRemoved()</code> event.</p>

      *

      * @param event Event to be processed

      */

     public void contextDestroyed(ServletContextEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.contextDestroyed(event);

         }

         // Remove any AbstractApplicationBean attributes, which will

         // trigger an attributeRemoved event

         List list = new ArrayList();

         Enumeration names = event.getServletContext().getAttributeNames();

         while (names.hasMoreElements()) {

             String name = (String) names.nextElement();

             list.add(name);

         }

         Iterator keys = list.iterator();

         while (keys.hasNext()) {

             String key = (String) keys.next();

             event.getServletContext().removeAttribute(key);

         }

     }

     // --------------------------------- ServletContextAttributeListener Methods

     /**

      * <p>Respond to an application scope attribute being added.  If the

      * value is an {@link AbstractApplicationBean}, call its

      * <code>init()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeAdded(ServletContextAttributeEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeAdded(event);

             return; // Tiger logic replaces our own

         }

         // If the new value is an AbstractApplicationBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireApplicationInit(value);

         }

     }

     /**

      * <p>Respond to an application scope attribute being replaced.

      * If the old value was an {@link AbstractApplicationBean}, call

      * its <code>destroy()</code> method.  If the new value is an

      * {@link AbstractApplicationBean}, call its <code>init()</code>

      * method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeReplaced(ServletContextAttributeEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeReplaced(event);

             return; // Tiger logic replaces our own

         }

         // If the old value is an AbstractApplicationBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireApplicationDestroy(value);

         }

         // If the new value is an AbstractApplicationBean, notify it

         value = event.getServletContext().getAttribute(event.getName());

         if (value != null) {

             fireApplicationInit(value);

         }

     }

     /**

      * <p>Respond to an application scope attribute being removed.

      * If the old value was an {@link AbstractApplicationBean}, call

      * its <code>destroy()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeRemoved(ServletContextAttributeEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeRemoved(event);

             return; // Tiger logic replaces our own

         }

         // If the old value is an AbstractApplicationBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireApplicationDestroy(value);

         }

     }

     // --------------------------------------------- HttpSessionListener Methods

     /**

      * <p>Respond to a session created event.  No special processing

      * is required.</p>

      *

      * @param event Event to be processed

      */

     public void sessionCreated(HttpSessionEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.sessionCreated(event);

         }

     }

     /**

      * <p>Respond to a session destroyed event.  Causes any session

      * scope attribute that implements {@link AbstractSessionBean}

      * to be removed, triggering an <code>attributeRemoved()</code> event.</p>

      *

      * @param event Event to be processed

      */

     public void sessionDestroyed(HttpSessionEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.sessionDestroyed(event);

         }

         // Remove any AbstractSessionBean attributes, which will

         // trigger an attributeRemoved event

         List list = new ArrayList();

         try {

             Enumeration names = event.getSession().getAttributeNames();

             while (names.hasMoreElements()) {

                 String name = (String) names.nextElement();

                 list.add(name);

             }

             Iterator keys = list.iterator();

             while (keys.hasNext()) {

                 String key = (String) keys.next();

                 event.getSession().removeAttribute(key);

             }

         } catch (IllegalStateException e) {

             // If the session has already been invalidated, there is nothing

             // we can do.  In a Servlet 2.4 or later container, this should not

             // happen, because the event handler is supposed to be called before

             // invalidation occurs, rather than after.

             ;

         }

     }

     // ----------------------------------- HttpSessionActivationListener Methods

     /**

      * <p>Respond to a "session will passivate" event.  Notify all session

      * scope attributes that are {@link AbstractSessionBean}s.</p>

      *

      * @param event Event to be processed

      */

     public void sessionWillPassivate(HttpSessionEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.sessionWillPassivate(event);

             return; // Tiger logic replaces our own

         }

         // Notify any AbstractSessionBean attributes

         Enumeration names = event.getSession().getAttributeNames();

         while (names.hasMoreElements()) {

             String name = (String) names.nextElement();

             Object value = event.getSession().getAttribute(name);

             if (value != null) {

                 fireSessionPassivate(value);

             }

         }

     }

     /**

      * <p>Respond to a "session did activate" event.  Notify all session

      * scope attributes that are {@link AbstractSessionBean}s.</p>

      *

      * @param event Event to be processed

      */

     public void sessionDidActivate(HttpSessionEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.sessionDidActivate(event);

             return; // Tiger logic replaces our own

         }

         // Notify any AbstractSessionBean attributes

         Enumeration names = event.getSession().getAttributeNames();

         while (names.hasMoreElements()) {

             String name = (String) names.nextElement();

             Object value = event.getSession().getAttribute(name);

             if (value != null) {

                 fireSessionActivate(value);

             }

         }

     }

     // ------------------------------------ HttpSessionAttributeListener Methods

     /**

      * <p>Respond to a session scope attribute being added.  If the

      * value is an {@link AbstractSessionBean}, call its

      * <code>init()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeAdded(HttpSessionBindingEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeAdded(event);

             return; // Tiger logic replaces our own

         }

         // If the new value is an AbstractSessionBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireSessionInit(value);

         }

     }

     /**

      * <p>Respond to a session scope attribute being replaced.

      * If the old value was an {@link AbstractSessionBean}, call

      * its <code>destroy()</code> method.  If the new value is an

      * {@link AbstractSessionBean}, call its <code>init()</code>

      * method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeReplaced(HttpSessionBindingEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeReplaced(event);

             return; // Tiger logic replaces our own

         }

         // If the old value is an AbstractSessionBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireSessionDestroy(value);

         }

         // If the new value is an AbstractSessionBean, notify it

         value = event.getSession().getAttribute(event.getName());

         if (value != null) {

             fireSessionInit(value);

         }

     }

     /**

      * <p>Respond to a session scope attribute being removed.

      * If the old value was an {@link AbstractSessionBean}, call

      * its <code>destroy()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeRemoved(HttpSessionBindingEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeRemoved(event);

             return; // Tiger logic replaces our own

         }

         // If the old value is an AbstractSessionBean, notify it

         Object value = event.getValue();

         if (value != null) {

             fireSessionDestroy(value);

         }

     }

     // ------------------------------------------ ServletRequestListener Methods

     /**

      * <p>Respond to a request created event.  No special processing

      * is required.</p>

      *

      * @param event Event to be processed

      */

     public void requestInitialized(ServletRequestEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.requestInitialized(event);

         }

     }

     /**

      * <p>Respond to a request destroyed event.  Causes any request

      * scope attribute that implements {@link AbstractRequestBean}

      * or {@link AbstractFragmentBean} to be removed, triggering an

      * <code>attributeRemoved()</code> event.</p>

      *

      * @param event Event to be processed

      */

     public void requestDestroyed(ServletRequestEvent event) {

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.requestDestroyed(event);

         }

         // Remove any AbstractRequestBean or ViewController attributes,

         // which will trigger an attributeRemoved event

         List list = new ArrayList();

         ServletRequest request = event.getServletRequest();

         Enumeration names = request.getAttributeNames();

         while (names.hasMoreElements()) {

             String name = (String) names.nextElement();

             Object value = request.getAttribute(name);

             if ((value instanceof AbstractRequestBean) || (value instanceof ViewController)) {

                 list.add(name);

             }

         }

         Iterator keys = list.iterator();

         while (keys.hasNext()) {

             String key = (String) keys.next();

             event.getServletRequest().removeAttribute(key);

         }

     }

     // --------------------------------- ServletRequestAttributeListener Methods

     /**

      * <p>Respond to a request scope attribute being added.  If the

      * value is an {@link AbstractRequestBean}, call its <code>init()</code> method.

      * </p>

      *

      * @param event Event to be processed

      */

     public void attributeAdded(ServletRequestAttributeEvent event) {

         if (log.isDebugEnabled()) {

             log.debug("ServletRequestAttributeAdded(" + event.getName()

               + "," + event.getValue() + ")");

         }

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeAdded(event);

             return; // Tiger logic replaces our own

         }

         Object value = event.getValue();

         if (value != null) {

             fireRequestInit(value);

         }

     }

     /**

      * <p>Respond to a request scope attribute being replaced.

      * If the old value was an {@link AbstractRequestBean},

      * call its <code>destroy()</code> method.  If the new value is an

      * {@link AbstractRequestBean}, call its <code>init()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeReplaced(ServletRequestAttributeEvent event) {

         if (log.isDebugEnabled()) {

             log.debug("ServletRequestAttributeReplaced(" + event.getName()

               + "," + event.getValue()

               + "," + event.getServletRequest().getAttribute(event.getName())

               + ")");

         }

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeReplaced(event);

             return; // Tiger logic replaces our own

         }

         Object value = event.getValue();

         if (value != null) {

             fireRequestDestroy(value);

         }

         value = event.getServletRequest().getAttribute(event.getName());

         if (value != null) {

             fireRequestInit(value);

         }

     }

     /**

      * <p>Respond to a request scope attribute being removed.

      * If the old value was an {@link AbstractRequestBean},

      * call its <code>destroy()</code> method.</p>

      *

      * @param event Event to be processed

      */

     public void attributeRemoved(ServletRequestAttributeEvent event) {

         if (log.isDebugEnabled()) {

             log.debug("ServletRequestAttributeRemoved(" + event.getName()

               + "," + event.getValue() + ")");

         }

         // Delegate to the Tiger Extensions instance if it exists

         LifecycleListener tiger = tiger();

         if (tiger != null) {

             tiger.attributeRemoved(event);

             return; // Tiger logic replaces our own

         }

         Object value = event.getValue();

         if (value != null) {

             fireRequestDestroy(value);

         }

     }

     // ------------------------------------------------------- Protected Methods

     /**

      * <p>Fire a destroy event on an @{link AbstractApplicationBean}.</p>

      *

      * @param bean {@link AbstractApplicationBean} to fire event on

      */

     protected void fireApplicationDestroy(Object bean) {

         try {

             if (bean instanceof AbstractApplicationBean) {

                 ((AbstractApplicationBean) bean).destroy();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire an init event on an {@link AbstractApplicationBean}.</p>

      *

      * @param bean {@link AbstractApplicationBean} to fire event on

      */

     protected void fireApplicationInit(Object bean) {

         try {

             if (bean instanceof AbstractApplicationBean) {

                 ((AbstractApplicationBean) bean).init();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire a destroy event on an @{link AbstractRequestBean}.</p>

      *

      * @param bean {@link AbstractRequestBean} to fire event on

      */

     protected void fireRequestDestroy(Object bean) {

         try {

             if (bean instanceof AbstractRequestBean) {

                 ((AbstractRequestBean) bean).destroy();

             } else if (bean instanceof ViewController) {

                 ((ViewController) bean).destroy();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire an init event on an {@link AbstractRequestBean}.</p>

      *

      * @param bean {@link AbstractRequestBean} to fire event on

      */

     protected void fireRequestInit(Object bean) {

         try {

             if (bean instanceof AbstractRequestBean) {

                 ((AbstractRequestBean) bean).init();

             } else if (bean instanceof ViewController) {

                 ((ViewController) bean).init();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire an activate event on an @{link AbstractSessionBean}.</p>

      *

      * @param bean {@link AbstractSessionBean} to fire event on

      */

     protected void fireSessionActivate(Object bean) {

         try {

             if (bean instanceof AbstractSessionBean) {

                 ((AbstractSessionBean) bean).activate();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire a destroy event on an @{link AbstractSessionBean}.</p>

      *

      * @param bean {@link AbstractSessionBean} to fire event on

      */

     protected void fireSessionDestroy(Object bean) {

         try {

             if (bean instanceof AbstractSessionBean) {

                 ((AbstractSessionBean) bean).destroy();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire an init event on an {@link AbstractSessionBean}.</p>

      *

      * @param bean {@link AbstractSessionBean} to fire event on

      */

     protected void fireSessionInit(Object bean) {

         try {

             if (bean instanceof AbstractSessionBean) {

                 ((AbstractSessionBean) bean).init();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Fire an passivate event on an @{link AbstractSessionBean}.</p>

      *

      * @param bean {@link AbstractSessionBean} to fire event on

      */

     protected void fireSessionPassivate(Object bean) {

         try {

             if (bean instanceof AbstractSessionBean) {

                 ((AbstractSessionBean) bean).passivate();

             }

         } catch (Exception e) {

             handleException(FacesContext.getCurrentInstance(), e);

         }

     }

     /**

      * <p>Handle the specified exception according to the strategy

      * defined by our current {@link ExceptionHandler}.</p>

      *

      * @param context FacesContext for the current request

      * @param exception Exception to be handled

      */

     protected void handleException(FacesContext context, Exception exception) {

         if (context == null) {

             exception.printStackTrace(System.out);

             return;

         }

         ExceptionHandler handler = (ExceptionHandler)

           context.getApplication().getVariableResolver().resolveVariable

                 (context, Constants.EXCEPTION_HANDLER);

         handler.handleException(exception);

     }

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

     /**

      * <p>Return the <em>Tiger Extensions</em> implementation of this listener

      * if one exists; otherwise, return <code>null</code>.</p>

      */

     private LifecycleListener tiger() {

         // If we have already attempted to load the Tiger Extensions version

         // of this class, return the calculated result

         if (tigerInitialized) {

             return tiger;

         }

         // Attempt to load the Tiger Extensions version of this class, and

         // instantiate an appropriate instance

         try {

             Class clazz = this.getClass().getClassLoader().loadClass(TIGER_LISTENER);

             tiger = (LifecycleListener) clazz.newInstance();

         } catch (Exception e) {

             ; // Swallow any class not found or instantiation exception

         }

         // Return the calculated result

         tigerInitialized = true;

         return tiger;

     }

 }