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.io.IOException;

 import java.util.ArrayList;

 import java.util.List;

 import java.util.Map;

 import javax.faces.component.UINamingContainer;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.shale.util.Messages;

 import org.apache.shale.view.Constants;

 import org.apache.shale.view.ExceptionHandler;

 import org.apache.shale.view.ViewController;

 /**

  * <p>Specialized implementation of <code>UINamingContainer</code> that

  * provides {@link ViewController} functionality for subviews.</p>

  *

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

  */

 public class SubviewComponent extends UINamingContainer {

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

     /**

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

      */

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

     /**

      * <p>Message resources for this class.</p>

      */

     private static Messages messages =

       new Messages("org.apache.shale.view.resources.Bundle",

                    SubviewComponent.class.getClassLoader());

     // ----------------------------------------------------- UIComponent Methods

     /**

      * <p>Return the component family for this component.</p>

      */

     public String getFamily() {

         return "org.apache.shale.view.Subview";

     }

     /**

      * <p>Prior to the standard processing, call the <code>prerender()</code>

      * callback on the {@link ViewController} associated with this subview,

      * if any.</p>

      *

      * @param context <code>FacesContext</code> for the current request

      *

      * @exception IOException if an input/output error occurs

      */

     public void encodeBegin(FacesContext context) throws IOException {

         Object vc = getViewController(context, false);

         if (vc != null) {

             try {

                 getViewControllerCallbacks(context).prerender(vc);

             } catch (Exception e) {

                 handleException(context, e);

             }

         }

         super.encodeBegin(context);

     }

     /**

      * <p>Prior to the standard processing, call the <code>preprocess()</code>

      * callback on the {@link ViewController} associated with this subview,

      * if any.</p>

      *

      * @param context <code>FacesContext</code> for the current request

      */

     public void processDecodes(FacesContext context) {

         Object vc = getViewController(context, true);

         if (vc != null) {

             try {

                 getViewControllerCallbacks(context).preprocess(vc);

             } catch (Exception e) {

                 handleException(context, e);

             }

         }

         super.processDecodes(context);

     }

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

     /**

      * <p>Return the {@link ViewController} associated with this component,

      * if any; otherwise, return <code>null</code>.  Note that the signature

      * for this method is <code>Object</code>, because the instance might

      * have the <code>@View</code> annotation rather than implementing the

      * <code>ViewController</code> interface.</p>

      *

      * @param context <code>FacesContext</code> for the current request

      * @param postback Are we processing a postback?

      */

     private Object getViewController(FacesContext context,

                                      boolean postback) {

         // If there is an existing ViewController instance, return it

         // FIXME - different exception for class cast problems?

         String name = getId(); // Name of the managed bean we are looking for

         ExternalContext econtext = context.getExternalContext();

         Object vc = null;

         vc = econtext.getRequestMap().get(name);

         if (vc == null) {

             vc = econtext.getSessionMap().get(name);

         }

         if (vc == null) {

             vc = econtext.getApplicationMap().get(name);

         }

         if (vc != null) {

             return vc;

         }

         // Construct and initialize a new ViewController, if any is associated

         String expr = "#{" + name + "}";

         vc = context.getApplication().

            createValueBinding(expr).getValue(context);

         if (vc == null) {

             log.debug(messages.getMessage("subview.noBean",

                                           new Object[] { getId() }));

             return null;

         }

         // Initialize the ViewController as needed

         if (vc instanceof ViewController) {

             ((ViewController) vc).setPostBack(postback);

         }

         // Schedule this instance for later processing as needed

         Map map = econtext.getRequestMap();

         List list = (List) map.get(FacesConstants.VIEWS_INITIALIZED);

         if (list == null) {

             list = new ArrayList();

             map.put(FacesConstants.VIEWS_INITIALIZED, list);

         }

         list.add(vc);

         // Return the initialized ViewController

         return vc;

     }

     /**

      * <p>Return the <code>ViewControllerCallbacks</code> instance to be used

      * to forward prerender and preprocess callbacks to our view controller,

      * whether or not it implements the <code>ViewController</code> interface

      * (it may not if it is using the <code>@View</code> annotation from the

      * shale-tiger module).</p>

      *

      * @param context <code>FacesContext</code> for the current request

      */

     private ViewControllerCallbacks getViewControllerCallbacks(FacesContext context) {

         ViewControllerCallbacks vcb = (ViewControllerCallbacks)

           context.getApplication().getVariableResolver().resolveVariable

                 (context, FacesConstants.VIEW_CALLBACKS);

         return vcb;

     }

     /**

      * <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

      */

     private 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);

     }

 }