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.configuration; 018 019 import java.io.File; 020 import java.io.InputStream; 021 import java.io.OutputStream; 022 import java.net.MalformedURLException; 023 import java.net.URL; 024 025 import org.apache.commons.logging.Log; 026 import org.apache.commons.logging.LogFactory; 027 import org.apache.commons.logging.impl.NoOpLog; 028 029 /** 030 * Abstract layer to allow various types of file systems. 031 * @since 1.7 032 * @author <a 033 * href="http://commons.apache.org/configuration/team-list.html">Commons Configuration team</a> 034 * @version $Id: FileSystem.java 1209996 2011-12-03 20:24:21Z oheger $ 035 */ 036 public abstract class FileSystem 037 { 038 /** The name of the system property that can be used to set the file system class name */ 039 private static final String FILE_SYSTEM = "org.apache.commons.configuration.filesystem"; 040 041 /** The default file system */ 042 private static FileSystem fileSystem; 043 044 /** The Logger */ 045 private Log log; 046 047 /** FileSystem options provider */ 048 private FileOptionsProvider optionsProvider; 049 050 public FileSystem() 051 { 052 setLogger(null); 053 } 054 055 /** 056 * Returns the logger used by this FileSystem. 057 * 058 * @return the logger 059 */ 060 public Log getLogger() 061 { 062 return log; 063 } 064 065 /** 066 * Allows to set the logger to be used by this FileSystem. This 067 * method makes it possible for clients to exactly control logging behavior. 068 * Per default a logger is set that will ignore all log messages. Derived 069 * classes that want to enable logging should call this method during their 070 * initialization with the logger to be used. 071 * 072 * @param log the new logger 073 */ 074 public void setLogger(Log log) 075 { 076 this.log = (log != null) ? log : new NoOpLog(); 077 } 078 079 static 080 { 081 String fsClassName = System.getProperty(FILE_SYSTEM); 082 if (fsClassName != null) 083 { 084 Log log = LogFactory.getLog(FileSystem.class); 085 086 try 087 { 088 Class<?> clazz = Class.forName(fsClassName); 089 if (FileSystem.class.isAssignableFrom(clazz)) 090 { 091 fileSystem = (FileSystem) clazz.newInstance(); 092 if (log.isDebugEnabled()) 093 { 094 log.debug("Using " + fsClassName); 095 } 096 } 097 } 098 catch (InstantiationException ex) 099 { 100 log.error("Unable to create " + fsClassName, ex); 101 } 102 catch (IllegalAccessException ex) 103 { 104 log.error("Unable to create " + fsClassName, ex); 105 } 106 catch (ClassNotFoundException ex) 107 { 108 log.error("Unable to create " + fsClassName, ex); 109 } 110 } 111 112 if (fileSystem == null) 113 { 114 fileSystem = new DefaultFileSystem(); 115 } 116 } 117 118 /** 119 * Set the FileSystem to use. 120 * @param fs The FileSystem 121 * @throws NullPointerException if the FileSystem parameter is null. 122 */ 123 public static void setDefaultFileSystem(FileSystem fs) throws NullPointerException 124 { 125 if (fs == null) 126 { 127 throw new NullPointerException("A FileSystem implementation is required"); 128 } 129 fileSystem = fs; 130 } 131 132 /** 133 * Reset the FileSystem to the default. 134 */ 135 public static void resetDefaultFileSystem() 136 { 137 fileSystem = new DefaultFileSystem(); 138 } 139 140 /** 141 * Retrieve the FileSystem being used. 142 * @return The FileSystem. 143 */ 144 public static FileSystem getDefaultFileSystem() 145 { 146 return fileSystem; 147 } 148 149 /** 150 * Set the FileOptionsProvider 151 * @param provider The FileOptionsProvider 152 */ 153 public void setFileOptionsProvider(FileOptionsProvider provider) 154 { 155 this.optionsProvider = provider; 156 } 157 158 public FileOptionsProvider getFileOptionsProvider() 159 { 160 return this.optionsProvider; 161 } 162 163 public abstract InputStream getInputStream(String basePath, String fileName) 164 throws ConfigurationException; 165 166 public abstract InputStream getInputStream(URL url) throws ConfigurationException; 167 168 public abstract OutputStream getOutputStream(URL url) throws ConfigurationException; 169 170 public abstract OutputStream getOutputStream(File file) throws ConfigurationException; 171 172 public abstract String getPath(File file, URL url, String basePath, String fileName); 173 174 public abstract String getBasePath(String path); 175 176 public abstract String getFileName(String path); 177 178 public abstract URL locateFromURL(String basePath, String fileName); 179 180 public abstract URL getURL(String basePath, String fileName) throws MalformedURLException; 181 }