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 * @version $Id: HomeDirectoryLocationStrategy.java 1842194 2018-09-27 22:24:23Z ggregory $ 047 */ 048public class HomeDirectoryLocationStrategy implements FileLocationStrategy 049{ 050 /** Constant for the system property with the user's home directory. */ 051 private static final String PROP_HOME = "user.home"; 052 053 /** The home directory to be searched for the requested file. */ 054 private final String homeDirectory; 055 056 /** The flag whether the base path is to be taken into account. */ 057 private final boolean evaluateBasePath; 058 059 /** 060 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and 061 * initializes it with the specified settings. 062 * 063 * @param homeDir the path to the home directory (can be <b>null</b>) 064 * @param withBasePath a flag whether the base path should be evaluated 065 */ 066 public HomeDirectoryLocationStrategy(final String homeDir, final boolean withBasePath) 067 { 068 homeDirectory = fetchHomeDirectory(homeDir); 069 evaluateBasePath = withBasePath; 070 } 071 072 /** 073 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and 074 * initializes the base path flag. The home directory is set to the user's 075 * home directory. 076 * 077 * @param withBasePath a flag whether the base path should be evaluated 078 */ 079 public HomeDirectoryLocationStrategy(final boolean withBasePath) 080 { 081 this(null, withBasePath); 082 } 083 084 /** 085 * Creates a new instance of {@code HomeDirectoryLocationStrategy} with 086 * default settings. The home directory is set to the user's home directory. 087 * The base path flag is set to <b>false</b> (which means that the base path 088 * is ignored). 089 */ 090 public HomeDirectoryLocationStrategy() 091 { 092 this(false); 093 } 094 095 /** 096 * Returns the home directory. In this directory the strategy searches for 097 * files. 098 * 099 * @return the home directory used by this object 100 */ 101 public String getHomeDirectory() 102 { 103 return homeDirectory; 104 } 105 106 /** 107 * Returns a flag whether the base path is to be taken into account when 108 * searching for a file. 109 * 110 * @return the flag whether the base path is evaluated 111 */ 112 public boolean isEvaluateBasePath() 113 { 114 return evaluateBasePath; 115 } 116 117 /** 118 * {@inheritDoc} This implementation searches in the home directory for a 119 * file described by the passed in {@code FileLocator}. If the locator 120 * defines a base path and the {@code evaluateBasePath} property is 121 * <b>true</b>, a sub directory of the home directory is searched. 122 */ 123 @Override 124 public URL locate(final FileSystem fileSystem, final FileLocator locator) 125 { 126 if (StringUtils.isNotEmpty(locator.getFileName())) 127 { 128 final String basePath = fetchBasePath(locator); 129 final File file = 130 FileLocatorUtils.constructFile(basePath, 131 locator.getFileName()); 132 if (file.isFile()) 133 { 134 return FileLocatorUtils.convertFileToURL(file); 135 } 136 } 137 138 return null; 139 } 140 141 /** 142 * Determines the base path to be used for the current locate() operation. 143 * 144 * @param locator the {@code FileLocator} 145 * @return the base path to be used 146 */ 147 private String fetchBasePath(final FileLocator locator) 148 { 149 if (isEvaluateBasePath() 150 && StringUtils.isNotEmpty(locator.getBasePath())) 151 { 152 return FileLocatorUtils.appendPath(getHomeDirectory(), 153 locator.getBasePath()); 154 } 155 return getHomeDirectory(); 156 } 157 158 /** 159 * Obtains the home directory to be used by a new instance. If a directory 160 * name is provided, it is used. Otherwise, the user's home directory is 161 * looked up. 162 * 163 * @param homeDir the passed in home directory 164 * @return the directory to be used 165 */ 166 private static String fetchHomeDirectory(final String homeDir) 167 { 168 return (homeDir != null) ? homeDir : System.getProperty(PROP_HOME); 169 } 170}