/*

  * 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.commons.jnet;

 import java.net.URLStreamHandler;

 import java.net.URLStreamHandlerFactory;

 /**

  * A parent aware url stream handler factory delegates to a parent

  * url stream handler factory,

  */

 public abstract class ParentAwareURLStreamHandlerFactory implements URLStreamHandlerFactory {

     protected URLStreamHandlerFactory parentFactory;

     /**

      * Set the parent factory.

      * @param factory

      */

     public void setParentFactory(URLStreamHandlerFactory factory) {

         this.parentFactory = factory;

     }

     /**

      * Return the parent factory.

      * @return The parent factory.

      */

     public URLStreamHandlerFactory getParent() {

         return this.parentFactory;

     }

     /**

      * @see java.net.URLStreamHandlerFactory#createURLStreamHandler(java.lang.String)

      */

     public URLStreamHandler createURLStreamHandler(String protocol) {

         URLStreamHandler handler = this.create(protocol);

         if ( handler == null && this.parentFactory != null ) {

             handler = this.parentFactory.createURLStreamHandler(protocol);

         }

         return handler;

     }

     /**

      * This method can be overwritten by subclasses to instantiate url stream

      * handlers for the given protocol.

      * @param protocol The protocol.

      * @return A url stream handler for the protocol or null.

      */

     protected abstract URLStreamHandler create(String protocol);

 }