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.faces;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import javax.faces.FacesException;
  import javax.faces.context.FacesContext;
  import javax.faces.el.EvaluationException;
  import javax.faces.el.VariableResolver;
  import javax.naming.Context;
  import javax.naming.InitialContext;
  import javax.naming.NamingException;
  
  /***
   * <p>Shale-specific VariableResolver for evaluating JavaServer Faces
   * value binding and method binding expressions.  The following special
   * variable names are recognized, and evaluated as indicated:</p>
   * <ul>
   * <li><strong>jndi</strong> - Returns the JNDI context at name
   *     <code>java:comp/env</code> (relative to the initial context
   *     supplied by the container.</li>
   * </ul>
   * <p>All other evaluations are delegated to the previous implementation
   * that was passed to our constructor.</p>
   *
   * <p>Since 1.0.1, if the optional <code>shale-tiger.jar</code> file
   * (containing the Shale Tiger Extensions) is available to this web
   * application, the extra variable resolver implementation found there
   * will be interposed between this instance and the previous
   * implementation instance passed to our constructor.</p>
   *
   * $Id: ShaleVariableResolver.java 464373 2006-10-16 04:21:54Z rahul $
   */
  public class ShaleVariableResolver extends VariableResolver {
  
  
      // ------------------------------------------------------------- Constructor
  
  
      /***
       * <p>Construct a new {@link ShaleVariableResolver} instance.</p>
       *
       * @param original Original resolver to delegate to.
       */
      public ShaleVariableResolver(VariableResolver original) {
  
          // Determine if our optional resolver is present
          VariableResolver delegate = null;
          try {
              // Attempt to load the Shale Tiger Extensions class
              ClassLoader cl = Thread.currentThread().getContextClassLoader();
              Class clazz = cl.loadClass(TIGER_DELEGATE);
              // Instantiate a new instance, passing the original resolver
              Constructor constructor = clazz.getConstructor(VARIABLE_RESOLVER_ARGS);
              delegate =
                (VariableResolver) constructor.newInstance(new Object[] { original });
          } catch (ClassNotFoundException e) {
              delegate = null;
          } catch (RuntimeException e) {
              throw e;
          } catch (InvocationTargetException e) {
              Throwable cause = e.getCause();
              if (cause instanceof RuntimeException) {
                  throw (RuntimeException) cause;
              } else {
                  throw new FacesException(cause);
              }
          } catch (Exception e) {
              throw new FacesException(e);
          }
  
          if (delegate != null) {
              // Interpose our delegate into the chain
              this.original = delegate;
          } else {
              // Use the provided instance directly
              this.original = original;
          }
  
      }
  
  
      // ------------------------------------------------------ Instance Variables
 
 
     /***
      * <p>The original <code>VariableResolver</code> passed to our constructor.</p>
      */
     private VariableResolver original = null;
 
 
     // ------------------------------------------------------ Manifest Constants
 
 
     /***
      * <p>Variable name to be resoved to our JNDI environment context.</p>
      */
     private static final String JNDI_VARIABLE_NAME = "jndi";
 
 
     /***
      * <p>Fully qualified class name of the variable resolver implementation
      * in the Shale Tiger Extensions library.</p>
      */
     private static final String TIGER_DELEGATE =
             "org.apache.shale.tiger.faces.VariableResolverImpl";
 
 
     /***
      * <p>Constructor signature for a VariableResolver that takes a
      * VariableResolver as a parameter.</p>
      */
     private static final Class VARIABLE_RESOLVER_ARGS[] =
     { VariableResolver.class };
 
 
     // ------------------------------------------------ VariableResolver Methods
 
 
     /***
      * <p>Resolve variable names known to this resolver; otherwise, delegate to
      * the original resolver passed to our constructor.</p>
      *
      * @param context FacesContext for the current request
      * @param name Variable name to be resolved
      *
      * @exception EvaluationException if the JNDI naming context
      *  throws a naming exception
      */
     public Object resolveVariable(FacesContext context, String name)
       throws EvaluationException {
 
         if (JNDI_VARIABLE_NAME.equals(name)) {
             try {
                 InitialContext ic = new InitialContext();
                 return (Context) ic.lookup("java:comp/env");
             } catch (NamingException e) {
                 throw new EvaluationException(e);
             }
         } else {
             return original.resolveVariable(context, name);
         }
 
     }
 
 
 }