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.names; 018 019 import java.util.Vector; 020 021 import org.apache.commons.discovery.ResourceNameDiscover; 022 import org.apache.commons.discovery.ResourceNameIterator; 023 import org.apache.commons.discovery.log.DiscoveryLogFactory; 024 import org.apache.commons.logging.Log; 025 026 027 /** 028 * Holder for multiple ResourceNameDiscover instances. 029 * The result is the union of the results from each 030 * (not a chained sequence, where results feed the next in line. 031 * 032 * @author Richard A. Sitze 033 */ 034 public class NameDiscoverers 035 extends ResourceNameDiscoverImpl 036 implements ResourceNameDiscover 037 { 038 private static Log log = DiscoveryLogFactory.newLog(NameDiscoverers.class); 039 public static void setLog(Log _log) { 040 log = _log; 041 } 042 043 private Vector discoverers = new Vector(); 044 045 /** 046 * Construct a new resource name discoverer 047 */ 048 public NameDiscoverers() { 049 } 050 051 /** 052 * Specify an additional class loader to be used in searching. 053 * The order of loaders determines the order of the result. 054 * It is recommended to add the most specific loaders first. 055 */ 056 public void addResourceNameDiscover(ResourceNameDiscover discover) { 057 if (discover != null) { 058 discoverers.addElement(discover); 059 } 060 } 061 062 protected ResourceNameDiscover getResourceNameDiscover(int idx) { 063 return (ResourceNameDiscover)discoverers.get(idx); 064 } 065 066 protected int size() { 067 return discoverers.size(); 068 } 069 070 /** 071 * Set of results of all discoverers. 072 * 073 * @return ResourceIterator 074 */ 075 public ResourceNameIterator findResourceNames(final String resourceName) { 076 if (log.isDebugEnabled()) 077 log.debug("find: resourceName='" + resourceName + "'"); 078 079 return new ResourceNameIterator() { 080 private int idx = 0; 081 private ResourceNameIterator iterator = null; 082 083 public boolean hasNext() { 084 if (iterator == null || !iterator.hasNext()) { 085 iterator = getNextIterator(); 086 if (iterator == null) { 087 return false; 088 } 089 } 090 return iterator.hasNext(); 091 } 092 093 public String nextResourceName() { 094 return iterator.nextResourceName(); 095 } 096 097 private ResourceNameIterator getNextIterator() { 098 while (idx < size()) { 099 ResourceNameIterator iter = 100 getResourceNameDiscover(idx++).findResourceNames(resourceName); 101 102 if (iter.hasNext()) { 103 return iter; 104 } 105 } 106 return null; 107 } 108 }; 109 } 110 }