001// Copyright 2006, 2007, 2008, 2012 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry5.ioc.internal.util; 016 017import org.apache.tapestry5.ioc.Resource; 018 019import java.net.URL; 020 021/** 022 * Implementation of {@link Resource} for files on the classpath (as defined by a {@link ClassLoader}). 023 */ 024public final class ClasspathResource extends AbstractResource 025{ 026 private final ClassLoader classLoader; 027 028 // Guarded by lock 029 private URL url; 030 031 // Guarded by lock 032 private boolean urlResolved; 033 034 public ClasspathResource(String path) 035 { 036 this(Thread.currentThread().getContextClassLoader(), path); 037 } 038 039 public ClasspathResource(ClassLoader classLoader, String path) 040 { 041 super(path); 042 assert classLoader != null; 043 044 this.classLoader = classLoader; 045 } 046 047 @Override 048 protected Resource newResource(String path) 049 { 050 return new ClasspathResource(classLoader, path); 051 } 052 053 public URL toURL() 054 { 055 try 056 { 057 acquireReadLock(); 058 059 if (!urlResolved) 060 { 061 resolveURL(); 062 } 063 064 return url; 065 } finally 066 { 067 releaseReadLock(); 068 } 069 } 070 071 private void resolveURL() 072 { 073 try 074 { 075 upgradeReadLockToWriteLock(); 076 077 if (!urlResolved) 078 { 079 url = classLoader.getResource(getPath()); 080 urlResolved = true; 081 } 082 } finally 083 { 084 downgradeWriteLockToReadLock(); 085 } 086 } 087 088 @Override 089 public boolean equals(Object obj) 090 { 091 if (obj == null) return false; 092 093 if (obj == this) return true; 094 095 if (obj.getClass() != getClass()) return false; 096 097 ClasspathResource other = (ClasspathResource) obj; 098 099 return other.classLoader == classLoader && other.getPath().equals(getPath()); 100 } 101 102 @Override 103 public int hashCode() 104 { 105 return 227 ^ getPath().hashCode(); 106 } 107 108 @Override 109 public String toString() 110 { 111 return "classpath:" + getPath(); 112 } 113 114}