/*

  * Copyright 2007-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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.kuali.rice.ken.util;

 import java.io.IOException;

 import java.util.ArrayList;

 import java.util.List;

 import org.apache.log4j.Logger;

 import org.xml.sax.EntityResolver;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 /**

  * EntityResolver implementation that delegates in sequence to a list of EntityResolvers,

  * returning the first match.

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class CompoundEntityResolver implements EntityResolver {

     private static final Logger LOG = Logger.getLogger(CompoundEntityResolver.class);

     private final List<EntityResolver> resolvers;

     /**

      * Constructs a CompoundEntityResolver.java.

      * @param first

      * @param second

      */

     public CompoundEntityResolver(EntityResolver first, EntityResolver second) {

         this.resolvers = new ArrayList<EntityResolver>(2);

         this.resolvers.add(first);

         this.resolvers.add(second);

     }

     /**

      * Constructs a CompoundEntityResolver.java.

      * @param resolvers

      */

     public CompoundEntityResolver(List<EntityResolver> resolvers) {

         this.resolvers = resolvers;

     }

     /**

      * @see org.xml.sax.EntityResolver#resolveEntity(java.lang.String, java.lang.String)

      */

     public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {

         LOG.debug("resolveEntity: " + publicId + " " + systemId);

         for (EntityResolver resolver: resolvers) {

             LOG.debug("Invoking entity resolver: " + resolver);

             InputSource source = resolver.resolveEntity(publicId, systemId);

             if (source != null) {

                 LOG.debug("source != null: " + source);

                 return source;

             }

         }

         return null;

     }

 }