1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.configuration2.io;
18
19 import java.io.File;
20 import java.net.URL;
21
22 import org.apache.commons.lang3.StringUtils;
23
24 /**
25 * <p>
26 * A specialized implementation of {@code FileLocationStrategy} which searches for files in the user's home directory or
27 * another special configurable directory.
28 * </p>
29 * <p>
30 * This strategy implementation ignores the URL stored in the passed in {@link FileLocator}. It constructs a file path
31 * from the configured home directory (which is the user's home directory per default, but can be changed to another
32 * path), optionally the base path, and the file name. If the resulting path points to an existing file, its URL is
33 * returned.
34 * </p>
35 * <p>
36 * When constructing an instance it can be configured whether the base path should be taken into account. If this option
37 * is set, the base path is appended to the home directory if it is not <b>null</b>. This is useful for instance to
38 * select a specific sub directory of the user's home directory. If this option is set to <b>false</b>, the base path is
39 * always ignored, and only the file name is evaluated.
40 * </p>
41 */
42 public class HomeDirectoryLocationStrategy implements FileLocationStrategy {
43 /** Constant for the system property with the user's home directory. */
44 private static final String PROP_HOME = "user.home";
45
46 /** The home directory to be searched for the requested file. */
47 private final String homeDirectory;
48
49 /** The flag whether the base path is to be taken into account. */
50 private final boolean evaluateBasePath;
51
52 /**
53 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes it with the specified settings.
54 *
55 * @param homeDir the path to the home directory (can be <b>null</b>)
56 * @param withBasePath a flag whether the base path should be evaluated
57 */
58 public HomeDirectoryLocationStrategy(final String homeDir, final boolean withBasePath) {
59 homeDirectory = fetchHomeDirectory(homeDir);
60 evaluateBasePath = withBasePath;
61 }
62
63 /**
64 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes the base path flag. The home
65 * directory is set to the user's home directory.
66 *
67 * @param withBasePath a flag whether the base path should be evaluated
68 */
69 public HomeDirectoryLocationStrategy(final boolean withBasePath) {
70 this(null, withBasePath);
71 }
72
73 /**
74 * Creates a new instance of {@code HomeDirectoryLocationStrategy} with default settings. The home directory is set to
75 * the user's home directory. The base path flag is set to <b>false</b> (which means that the base path is ignored).
76 */
77 public HomeDirectoryLocationStrategy() {
78 this(false);
79 }
80
81 /**
82 * Gets the home directory. In this directory the strategy searches for files.
83 *
84 * @return the home directory used by this object
85 */
86 public String getHomeDirectory() {
87 return homeDirectory;
88 }
89
90 /**
91 * Returns a flag whether the base path is to be taken into account when searching for a file.
92 *
93 * @return the flag whether the base path is evaluated
94 */
95 public boolean isEvaluateBasePath() {
96 return evaluateBasePath;
97 }
98
99 /**
100 * {@inheritDoc} This implementation searches in the home directory for a file described by the passed in
101 * {@code FileLocator}. If the locator defines a base path and the {@code evaluateBasePath} property is <b>true</b>, a
102 * sub directory of the home directory is searched.
103 */
104 @Override
105 public URL locate(final FileSystem fileSystem, final FileLocator locator) {
106 if (StringUtils.isNotEmpty(locator.getFileName())) {
107 final String basePath = fetchBasePath(locator);
108 final File file = FileLocatorUtils.constructFile(basePath, locator.getFileName());
109 if (file.isFile()) {
110 return FileLocatorUtils.convertFileToURL(file);
111 }
112 }
113
114 return null;
115 }
116
117 /**
118 * Determines the base path to be used for the current locate() operation.
119 *
120 * @param locator the {@code FileLocator}
121 * @return the base path to be used
122 */
123 private String fetchBasePath(final FileLocator locator) {
124 if (isEvaluateBasePath() && StringUtils.isNotEmpty(locator.getBasePath())) {
125 return FileLocatorUtils.appendPath(getHomeDirectory(), locator.getBasePath());
126 }
127 return getHomeDirectory();
128 }
129
130 /**
131 * Obtains the home directory to be used by a new instance. If a directory name is provided, it is used. Otherwise, the
132 * user's home directory is looked up.
133 *
134 * @param homeDir the passed in home directory
135 * @return the directory to be used
136 */
137 private static String fetchHomeDirectory(final String homeDir) {
138 return homeDir != null ? homeDir : System.getProperty(PROP_HOME);
139 }
140 }