001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.jnet; 018 019 import java.net.URLStreamHandler; 020 import java.net.URLStreamHandlerFactory; 021 022 /** 023 * A parent aware url stream handler factory delegates to a parent 024 * url stream handler factory, 025 */ 026 public abstract class ParentAwareURLStreamHandlerFactory implements URLStreamHandlerFactory { 027 028 protected URLStreamHandlerFactory parentFactory; 029 030 /** 031 * Set the parent factory. 032 * @param factory 033 */ 034 public void setParentFactory(URLStreamHandlerFactory factory) { 035 this.parentFactory = factory; 036 } 037 038 /** 039 * Return the parent factory. 040 * @return The parent factory. 041 */ 042 public URLStreamHandlerFactory getParent() { 043 return this.parentFactory; 044 } 045 046 /** 047 * @see java.net.URLStreamHandlerFactory#createURLStreamHandler(java.lang.String) 048 */ 049 public URLStreamHandler createURLStreamHandler(String protocol) { 050 URLStreamHandler handler = this.create(protocol); 051 if ( handler == null && this.parentFactory != null ) { 052 handler = this.parentFactory.createURLStreamHandler(protocol); 053 } 054 return handler; 055 } 056 057 /** 058 * This method can be overwritten by subclasses to instantiate url stream 059 * handlers for the given protocol. 060 * @param protocol The protocol. 061 * @return A url stream handler for the protocol or null. 062 */ 063 protected abstract URLStreamHandler create(String protocol); 064 }