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.discovery.resource; 018 019 import java.io.IOException; 020 import java.net.URL; 021 import java.util.Enumeration; 022 023 import org.apache.commons.discovery.Resource; 024 import org.apache.commons.discovery.ResourceDiscover; 025 import org.apache.commons.discovery.ResourceIterator; 026 import org.apache.commons.discovery.jdk.JDKHooks; 027 import org.apache.commons.discovery.log.DiscoveryLogFactory; 028 import org.apache.commons.logging.Log; 029 030 031 /** 032 * @author Richard A. Sitze 033 * @author Craig R. McClanahan 034 * @author Costin Manolache 035 * @author James Strachan 036 */ 037 public class DiscoverResources 038 extends ResourceDiscoverImpl 039 implements ResourceDiscover 040 { 041 private static Log log = DiscoveryLogFactory.newLog(DiscoverResources.class); 042 public static void setLog(Log _log) { 043 log = _log; 044 } 045 046 /** 047 * Construct a new resource discoverer 048 */ 049 public DiscoverResources() { 050 super(); 051 } 052 053 /** 054 * Construct a new resource discoverer 055 */ 056 public DiscoverResources(ClassLoaders classLoaders) { 057 super(classLoaders); 058 } 059 060 /** 061 * @return ResourceIterator 062 */ 063 public ResourceIterator findResources(final String resourceName) { 064 if (log.isDebugEnabled()) 065 log.debug("find: resourceName='" + resourceName + "'"); 066 067 return new ResourceIterator() { 068 private int idx = 0; 069 private ClassLoader loader = null; 070 private Enumeration resources = null; 071 private Resource resource = null; 072 073 public boolean hasNext() { 074 if (resource == null) { 075 resource = getNextResource(); 076 } 077 return resource != null; 078 } 079 080 public Resource nextResource() { 081 Resource element = resource; 082 resource = null; 083 return element; 084 } 085 086 private Resource getNextResource() { 087 if (resources == null || !resources.hasMoreElements()) { 088 resources = getNextResources(); 089 } 090 091 Resource resourceInfo; 092 if (resources != null) { 093 URL url = (URL)resources.nextElement(); 094 095 if (log.isDebugEnabled()) 096 log.debug("getNextResource: next URL='" + url + "'"); 097 098 resourceInfo = new Resource(resourceName, url, loader); 099 } else { 100 resourceInfo = null; 101 } 102 103 return resourceInfo; 104 } 105 106 private Enumeration getNextResources() { 107 while (idx < getClassLoaders().size()) { 108 loader = getClassLoaders().get(idx++); 109 if (log.isDebugEnabled()) 110 log.debug("getNextResources: search using ClassLoader '" + loader + "'"); 111 try { 112 Enumeration e = JDKHooks.getJDKHooks().getResources(loader, resourceName); 113 if (e != null && e.hasMoreElements()) { 114 return e; 115 } 116 } catch( IOException ex ) { 117 log.warn("getNextResources: Ignoring Exception", ex); 118 } 119 } 120 return null; 121 } 122 }; 123 } 124 }