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 */ 017package org.apache.commons.configuration2.io; 018 019import java.io.File; 020import java.net.URL; 021 022import org.apache.commons.lang3.StringUtils; 023 024/** 025 * <p> 026 * A specialized implementation of {@code FileLocationStrategy} which searches 027 * for files in the user's home directory or another special configurable 028 * directory. 029 * </p> 030 * <p> 031 * This strategy implementation ignores the URL stored in the passed in 032 * {@link FileLocator}. It constructs a file path from the configured home 033 * directory (which is the user's home directory per default, but can be changed 034 * to another path), optionally the base path, and the file name. If the 035 * resulting path points to an existing file, its URL is returned. 036 * </p> 037 * <p> 038 * When constructing an instance it can be configured whether the base path 039 * should be taken into account. If this option is set, the base path is 040 * appended to the home directory if it is not <b>null</b>. This is useful for 041 * instance to select a specific sub directory of the user's home directory. If 042 * this option is set to <b>false</b>, the base path is always ignored, and only 043 * the file name is evaluated. 044 * </p> 045 * 046 */ 047public class HomeDirectoryLocationStrategy implements FileLocationStrategy 048{ 049 /** Constant for the system property with the user's home directory. */ 050 private static final String PROP_HOME = "user.home"; 051 052 /** The home directory to be searched for the requested file. */ 053 private final String homeDirectory; 054 055 /** The flag whether the base path is to be taken into account. */ 056 private final boolean evaluateBasePath; 057 058 /** 059 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and 060 * initializes it with the specified settings. 061 * 062 * @param homeDir the path to the home directory (can be <b>null</b>) 063 * @param withBasePath a flag whether the base path should be evaluated 064 */ 065 public HomeDirectoryLocationStrategy(final String homeDir, final boolean withBasePath) 066 { 067 homeDirectory = fetchHomeDirectory(homeDir); 068 evaluateBasePath = withBasePath; 069 } 070 071 /** 072 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and 073 * initializes the base path flag. The home directory is set to the user's 074 * home directory. 075 * 076 * @param withBasePath a flag whether the base path should be evaluated 077 */ 078 public HomeDirectoryLocationStrategy(final boolean withBasePath) 079 { 080 this(null, withBasePath); 081 } 082 083 /** 084 * Creates a new instance of {@code HomeDirectoryLocationStrategy} with 085 * default settings. The home directory is set to the user's home directory. 086 * The base path flag is set to <b>false</b> (which means that the base path 087 * is ignored). 088 */ 089 public HomeDirectoryLocationStrategy() 090 { 091 this(false); 092 } 093 094 /** 095 * Returns the home directory. In this directory the strategy searches for 096 * files. 097 * 098 * @return the home directory used by this object 099 */ 100 public String getHomeDirectory() 101 { 102 return homeDirectory; 103 } 104 105 /** 106 * Returns a flag whether the base path is to be taken into account when 107 * searching for a file. 108 * 109 * @return the flag whether the base path is evaluated 110 */ 111 public boolean isEvaluateBasePath() 112 { 113 return evaluateBasePath; 114 } 115 116 /** 117 * {@inheritDoc} This implementation searches in the home directory for a 118 * file described by the passed in {@code FileLocator}. If the locator 119 * defines a base path and the {@code evaluateBasePath} property is 120 * <b>true</b>, a sub directory of the home directory is searched. 121 */ 122 @Override 123 public URL locate(final FileSystem fileSystem, final FileLocator locator) 124 { 125 if (StringUtils.isNotEmpty(locator.getFileName())) 126 { 127 final String basePath = fetchBasePath(locator); 128 final File file = 129 FileLocatorUtils.constructFile(basePath, 130 locator.getFileName()); 131 if (file.isFile()) 132 { 133 return FileLocatorUtils.convertFileToURL(file); 134 } 135 } 136 137 return null; 138 } 139 140 /** 141 * Determines the base path to be used for the current locate() operation. 142 * 143 * @param locator the {@code FileLocator} 144 * @return the base path to be used 145 */ 146 private String fetchBasePath(final FileLocator locator) 147 { 148 if (isEvaluateBasePath() 149 && StringUtils.isNotEmpty(locator.getBasePath())) 150 { 151 return FileLocatorUtils.appendPath(getHomeDirectory(), 152 locator.getBasePath()); 153 } 154 return getHomeDirectory(); 155 } 156 157 /** 158 * Obtains the home directory to be used by a new instance. If a directory 159 * name is provided, it is used. Otherwise, the user's home directory is 160 * looked up. 161 * 162 * @param homeDir the passed in home directory 163 * @return the directory to be used 164 */ 165 private static String fetchHomeDirectory(final String homeDir) 166 { 167 return homeDir != null ? homeDir : System.getProperty(PROP_HOME); 168 } 169}