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);

         }

     }

 }