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