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.geronimo.kernel.classloader; 018 019 import java.util.Enumeration; 020 import java.util.Iterator; 021 import java.util.Collection; 022 import java.util.NoSuchElementException; 023 024 /** 025 * @version $Rev: 476049 $ $Date: 2006-11-16 23:35:17 -0500 (Thu, 16 Nov 2006) $ 026 */ 027 public class ResourceEnumeration implements Enumeration { 028 private Iterator iterator; 029 private final String resourceName; 030 private Object next; 031 032 public ResourceEnumeration(Collection resourceLocations, String resourceName) { 033 this.iterator = resourceLocations.iterator(); 034 this.resourceName = resourceName; 035 } 036 037 public boolean hasMoreElements() { 038 fetchNext(); 039 return (next != null); 040 } 041 042 public Object nextElement() { 043 fetchNext(); 044 045 // save next into a local variable and clear the next field 046 Object next = this.next; 047 this.next = null; 048 049 // if we didn't have a next throw an exception 050 if (next == null) { 051 throw new NoSuchElementException(); 052 } 053 return next; 054 } 055 056 private void fetchNext() { 057 if (iterator == null) { 058 return; 059 } 060 if (next != null) { 061 return; 062 } 063 064 try { 065 while (iterator.hasNext()) { 066 ResourceLocation resourceLocation = (ResourceLocation) iterator.next(); 067 ResourceHandle resourceHandle = resourceLocation.getResourceHandle(resourceName); 068 if (resourceHandle != null) { 069 next = resourceHandle.getUrl(); 070 return; 071 } 072 } 073 // no more elements 074 // clear the iterator so it can be GCed 075 iterator = null; 076 } catch (IllegalStateException e) { 077 // Jar file was closed... this means the resource finder was destroyed 078 // clear the iterator so it can be GCed 079 iterator = null; 080 throw e; 081 } 082 } 083 }