1 /*
2 * Copyright 2008-2012 smartics, Kronseder & Reiner GmbH
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package de.smartics.util.test.properties;
17
18 import java.io.BufferedInputStream;
19 import java.io.IOException;
20 import java.io.InputStream;
21 import java.util.Properties;
22
23 import org.apache.commons.io.IOUtils;
24
25 /**
26 * A mapping from project-defined keys to values dependent on project
27 * properties.
28 * <p>
29 * This can be used in a <a href="http://maven.apache.org/">Maven</a>
30 * environment to derive GAV strings from POM dependencies, where the version
31 * numbers are defined as properties.
32 * </p>
33 * <p>
34 * Place a file named
35 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE} the
36 * root folder of the class path and provide a mapping from free-to-choose keys
37 * to GAV strings like this:
38 * </p>
39 *
40 * <pre>
41 * smartics-properties-core=de.smartics.properties:smartics-properties-core:${smartics-properties-core.version}
42 * </pre>
43 * <p>
44 * Using filtering to resolve the properties like
45 * <code>smartics-properties-core.version</code>.
46 * </p>
47 *
48 * <pre>
49 * {
50 * @source
51 * protected static final ProjectProperties PROJECT_PROPERTIES =
52 * new ProjectProperties(MyClass.class);
53 * }
54 * </pre>
55 * <p>
56 * Then you can fetch GAV strings resolved with the current version number from
57 * the POM by your keys.
58 * </p>
59 */
60 public final class ProjectProperties
61 {
62 // ********************************* Fields *********************************
63
64 // --- constants ------------------------------------------------------------
65
66 /**
67 * The name of the properties file searched in the class path root.
68 * <p>
69 * The value of this constant is {@value}.
70 * </p>
71 */
72 public static final String DEFAULT_RESOURCE = "artifacts.properties";
73
74 // --- members --------------------------------------------------------------
75
76 /**
77 * The mapping of project-defined keys to GAV strings.
78 */
79 private final Properties dictionary;
80
81 // ****************************** Initializer *******************************
82
83 // ****************************** Constructors ******************************
84
85 /**
86 * Constructor using the thread's context class loader.
87 */
88 public ProjectProperties()
89 {
90 this(Thread.currentThread().getContextClassLoader());
91 }
92
93 /**
94 * Constructor using a class to locate the
95 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE}.
96 *
97 * @param locator the class to access the class loader to search for
98 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE}
99 * .
100 */
101 public ProjectProperties(final Class<?> locator)
102 {
103 this(locator.getClassLoader()); // NOPMD
104 }
105
106 /**
107 * Constructor using a class loader to locate the
108 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE}.
109 *
110 * @param loader the class loader to search for
111 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE}
112 * .
113 */
114 public ProjectProperties(final ClassLoader loader)
115 {
116 dictionary = init(loader);
117 }
118
119 // ****************************** Inner Classes *****************************
120
121 // ********************************* Methods ********************************
122
123 // --- init -----------------------------------------------------------------
124
125 private static Properties init(final ClassLoader loader)
126 {
127 final Properties properties = new Properties();
128
129 InputStream input = loader.getResourceAsStream(DEFAULT_RESOURCE);
130 if (input != null)
131 {
132 try
133 {
134 input = new BufferedInputStream(input);
135 properties.load(input);
136 }
137 catch (final IOException e)
138 {
139 throw new IllegalStateException("Cannot read '" + DEFAULT_RESOURCE
140 + "'.", e);
141 }
142 finally
143 {
144 IOUtils.closeQuietly(input);
145 }
146 }
147
148 return properties;
149 }
150
151 // --- get&set --------------------------------------------------------------
152
153 // --- business -------------------------------------------------------------
154
155 /**
156 * Returns the GAV string for the given key.
157 *
158 * @param key a key defined in
159 * {@value de.smartics.confinale.test.ProjectProperties#DEFAULT_RESOURCE}
160 * .
161 * @return the value associated with the given {@code key}.
162 */
163 public String get(final String key)
164 {
165 return dictionary.getProperty(key);
166 }
167
168 // --- object basics --------------------------------------------------------
169
170 }