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 * https://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 import org.apache.commons.lang3.SystemProperties;
24
25 /**
26 * <p>
27 * A specialized implementation of {@code FileLocationStrategy} which searches for files in the user's home directory or
28 * another special configurable directory.
29 * </p>
30 * <p>
31 * This strategy implementation ignores the URL stored in the passed in {@link FileLocator}. It constructs a file path
32 * from the configured home directory (which is the user's home directory per default, but can be changed to another
33 * path), optionally the base path, and the file name. If the resulting path points to an existing file, its URL is
34 * returned.
35 * </p>
36 * <p>
37 * When constructing an instance it can be configured whether the base path should be taken into account. If this option
38 * is set, the base path is appended to the home directory if it is not <strong>null</strong>. This is useful for instance to
39 * select a specific sub directory of the user's home directory. If this option is set to <strong>false</strong>, the base path is
40 * always ignored, and only the file name is evaluated.
41 * </p>
42 */
43 public class HomeDirectoryLocationStrategy implements FileLocationStrategy {
44
45 /**
46 * Obtains the home directory to be used by a new instance. If a directory name is provided, it is used. Otherwise, the
47 * user's home directory is looked up.
48 *
49 * @param homeDir the passed in home directory
50 * @return the directory to be used
51 */
52 private static String fetchHomeDirectory(final String homeDir) {
53 return homeDir != null ? homeDir : SystemProperties.getUserHome();
54 }
55
56 /** The home directory to be searched for the requested file. */
57 private final String homeDirectory;
58
59 /** The flag whether the base path is to be taken into account. */
60 private final boolean evaluateBasePath;
61
62 /**
63 * Creates a new instance of {@code HomeDirectoryLocationStrategy} with default settings. The home directory is set to
64 * the user's home directory. The base path flag is set to <strong>false</strong> (which means that the base path is ignored).
65 */
66 public HomeDirectoryLocationStrategy() {
67 this(false);
68 }
69
70 /**
71 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes the base path flag. The home
72 * directory is set to the user's home directory.
73 *
74 * @param withBasePath a flag whether the base path should be evaluated
75 */
76 public HomeDirectoryLocationStrategy(final boolean withBasePath) {
77 this(null, withBasePath);
78 }
79
80 /**
81 * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes it with the specified settings.
82 *
83 * @param homeDir the path to the home directory (can be <strong>null</strong>)
84 * @param withBasePath a flag whether the base path should be evaluated
85 */
86 public HomeDirectoryLocationStrategy(final String homeDir, final boolean withBasePath) {
87 homeDirectory = fetchHomeDirectory(homeDir);
88 evaluateBasePath = withBasePath;
89 }
90
91 /**
92 * Determines the base path to be used for the current locate() operation.
93 *
94 * @param locator the {@code FileLocator}
95 * @return the base path to be used
96 */
97 private String fetchBasePath(final FileLocator locator) {
98 if (isEvaluateBasePath() && StringUtils.isNotEmpty(locator.getBasePath())) {
99 return FileLocatorUtils.appendPath(getHomeDirectory(), locator.getBasePath());
100 }
101 return getHomeDirectory();
102 }
103
104 /**
105 * Gets the home directory. In this directory the strategy searches for files.
106 *
107 * @return the home directory used by this object
108 */
109 public String getHomeDirectory() {
110 return homeDirectory;
111 }
112
113 /**
114 * Returns a flag whether the base path is to be taken into account when searching for a file.
115 *
116 * @return the flag whether the base path is evaluated
117 */
118 public boolean isEvaluateBasePath() {
119 return evaluateBasePath;
120 }
121
122 /**
123 * {@inheritDoc} This implementation searches in the home directory for a file described by the passed in
124 * {@code FileLocator}. If the locator defines a base path and the {@code evaluateBasePath} property is <strong>true</strong>, a
125 * sub directory of the home directory is searched.
126 */
127 @Override
128 public URL locate(final FileSystem fileSystem, final FileLocator locator) {
129 if (StringUtils.isNotEmpty(locator.getFileName())) {
130 final String basePath = fetchBasePath(locator);
131 final File file = FileLocatorUtils.constructFile(basePath, locator.getFileName());
132 if (file.isFile()) {
133 return FileLocatorUtils.convertFileToURL(file);
134 }
135 }
136
137 return null;
138 }
139 }