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);
 
     }
 
 
 }