001// Copyright 2006-2013 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 @Override 054 public URL toURL() 055 { 056 try 057 { 058 acquireReadLock(); 059 060 if (!urlResolved) 061 { 062 resolveURL(); 063 } 064 065 return url; 066 } finally 067 { 068 releaseReadLock(); 069 } 070 } 071 072 private void resolveURL() 073 { 074 try 075 { 076 upgradeReadLockToWriteLock(); 077 078 if (!urlResolved) 079 { 080 url = classLoader.getResource(getPath()); 081 082 validateURL(url); 083 084 urlResolved = true; 085 } 086 } finally 087 { 088 downgradeWriteLockToReadLock(); 089 } 090 091 092 } 093 094 @Override 095 public boolean equals(Object obj) 096 { 097 if (obj == null) return false; 098 099 if (obj == this) return true; 100 101 if (obj.getClass() != getClass()) return false; 102 103 ClasspathResource other = (ClasspathResource) obj; 104 105 return other.classLoader == classLoader && other.getPath().equals(getPath()); 106 } 107 108 @Override 109 public int hashCode() 110 { 111 return 227 ^ getPath().hashCode(); 112 } 113 114 @Override 115 public String toString() 116 { 117 return "classpath:" + getPath(); 118 } 119 120}