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.tiger.view.faces;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.util.HashMap;
  import java.util.Map;
  import javax.faces.context.FacesContext;
  import org.apache.shale.tiger.view.Preprocess;
  import org.apache.shale.tiger.view.Prerender;
  import org.apache.shale.tiger.view.View;
  import org.apache.shale.view.ViewController;
  import org.apache.shale.view.faces.ViewControllerCallbacks;
  
  /***
   * <p>Utility class to perform the event callbacks specified by the
   * {@link ViewController} interface.  This version will call through
   * to ViewController methods if the bean class actually implements this
   * interface, or ituses annotations to identify the relevant methods.</p>
   *
   * <p><strong>NOTE</strong> - The annotated callback methods must be
   * public, and take no arguments.  They may exist on the class of the
   * instance being passed in, or be inherited from a superclass.</p>
   *
   * $Id: ViewControllerCallbacks2.java 465074 2006-10-17 22:05:53Z rahul $
   *
   * @since 1.0.1
   */
  public class ViewControllerCallbacks2 extends ViewControllerCallbacks {
  
  
      // ------------------------------------------------------------ Constructors
  
  
      // ------------------------------------------------------ Instance Variables
  
  
      // ---------------------------------------------------------- Public Methods
  
  
      /***
       * <p>Perform the <code>preprocess</code> callback on the specified
       * instance.</p>
       *
       * @param instance Bean instance on which to perform this callback
       */
      public void preprocess(Object instance) {
  
          if (instance instanceof ViewController) {
              try {
                  ((ViewController) instance).preprocess();
              } catch (Exception e) {
                  handleException(FacesContext.getCurrentInstance(), e);
              }
              return;
          }
  
          Method method = method(instance, Preprocess.class);
          if (method != null) {
              try {
                  method.invoke(instance, new Object[0]);
              } catch (IllegalAccessException e) {
                  handleException(FacesContext.getCurrentInstance(), e);
              } catch (InvocationTargetException e) {
                  handleException(FacesContext.getCurrentInstance(), (Exception) e.getCause());
              }
          }
  
      }
  
  
      /***
       * <p>Perform the <code>prerender</code> callback on the specified
       * instance.</p>
       *
       * @param instance Bean instance on which to perform this callback
       */
      public void prerender(Object instance) {
  
          if (instance instanceof ViewController) {
              try {
                  ((ViewController) instance).prerender();
              } catch (Exception e) {
                 handleException(FacesContext.getCurrentInstance(), e);
             }
             return;
         }
 
         Method method = method(instance, Prerender.class);
         if (method != null) {
             try {
                 method.invoke(instance, new Object[0]);
             } catch (IllegalAccessException e) {
                 handleException(FacesContext.getCurrentInstance(), e);
             } catch (InvocationTargetException e) {
                 handleException(FacesContext.getCurrentInstance(), (Exception) e.getCause());
             }
         }
 
     }
 
 
     // --------------------------------------------------------- Private Methods
 
 
     /***
      * <p>The set of method annotations for callbacks of interest.</p>
      */
     private static final Class[] annotations =
     { Preprocess.class, Prerender.class };
 
 
 
     /***
      * <p>Data structure to maintain information about annotated
      * methods.  In this map, the key is the Class being analyzed,
      * and the value is an inner map.  In the inner map, the key
      * is an Annotation class, and the value is the corresponding
      * Method instance.</p>
      */
     private transient Map<Class,Map<Class,Method>> maps =
       new HashMap<Class,Map<Class,Method>>();
 
 
     /***
      * <p>Return the <code>Method</code> to be called for the specified
      * annotation on the specified instance, if any.  If there is no such
      * method, return <code>null</code>.</p>
      *
      * @param instance Instance on which callbacks will be performed
      * @param annotation Annotation for which to return a method
      */
     private Method method(Object instance, Class annotation) {
 
         // Does the underlying class implement the View annotation?
         // If not, exit early
         Class clazz = instance.getClass();
         if (clazz.getAnnotation(View.class) == null) {
             return null;
         }
 
         synchronized (maps) {
 
             // If we have seen this Class already, simply return the
             // previously located Method (if any)
             Map<Class,Method> map = maps.get(clazz);
             if (map != null) {
                 return map.get(annotation);
             }
 
             // Construct and cache a new Map identifying the
             // methods of interest for these callbacks
             map = new HashMap<Class,Method>();
             Method[] methods = clazz.getMethods();
             for (int i = 0; i < methods.length; i++) {
                 if (methods[i].getParameterTypes().length > 0) {
                     continue;
                 }
                 for (int j = 0; j < annotations.length; j++) {
                     if (methods[i].getAnnotation(annotations[j]) != null) {
                         map.put(annotations[j], methods[i]);
                     }
                 }
             }
             maps.put(clazz, map);
             return map.get(annotation);
 
         }
 
     }
 
 
 }