1 /*
2 * Copyright (C) 2010, Sasa Zivkov <sasa.zivkov@sap.com>
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.nls;
45
46 import java.util.Locale;
47 import java.util.concurrent.ConcurrentHashMap;
48
49 import org.eclipse.jgit.errors.TranslationBundleLoadingException;
50 import org.eclipse.jgit.errors.TranslationStringMissingException;
51
52 /**
53 * The purpose of this class is to provide NLS (National Language Support)
54 * configurable per thread.
55 *
56 * <p>
57 * The {@link #setLocale(Locale)} method is used to configure locale for the
58 * calling thread. The locale setting is thread inheritable. This means that a
59 * child thread will have the same locale setting as its creator thread until it
60 * changes it explicitly.
61 *
62 * <p>
63 * Example of usage:
64 *
65 * <pre>
66 * NLS.setLocale(Locale.GERMAN);
67 * TransportText t = NLS.getBundleFor(TransportText.class);
68 * </pre>
69 */
70 public class NLS {
71 /** The root locale constant. It is defined here because the Locale.ROOT is not defined in Java 5 */
72 public static final Locale ROOT_LOCALE = new Locale("", "", ""); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
73
74 private static final InheritableThreadLocal<NLS> local = new InheritableThreadLocal<NLS>() {
75 @Override
76 protected NLS initialValue() {
77 return new NLS(Locale.getDefault());
78 }
79 };
80
81 /**
82 * Sets the locale for the calling thread.
83 * <p>
84 * The {@link #getBundleFor(Class)} method will honor this setting if if it
85 * is supported by the provided resource bundle property files. Otherwise,
86 * it will use a fall back locale as described in the
87 * {@link TranslationBundle}
88 *
89 * @param locale
90 * the preferred locale
91 */
92 public static void setLocale(Locale locale) {
93 local.set(new NLS(locale));
94 }
95
96 /**
97 * Sets the JVM default locale as the locale for the calling thread.
98 * <p>
99 * Semantically this is equivalent to <code>NLS.setLocale(Locale.getDefault())</code>.
100 */
101 public static void useJVMDefaultLocale() {
102 local.set(new NLS(Locale.getDefault()));
103 }
104
105 /**
106 * Returns an instance of the translation bundle of the required type. All
107 * public String fields of the bundle instance will get their values
108 * injected as described in the {@link TranslationBundle}.
109 *
110 * @param <T>
111 * required bundle type
112 * @param type
113 * required bundle type
114 * @return an instance of the required bundle type
115 * @exception TranslationBundleLoadingException see {@link TranslationBundleLoadingException}
116 * @exception TranslationStringMissingException see {@link TranslationStringMissingException}
117 */
118 public static <T extends TranslationBundle> T getBundleFor(Class<T> type) {
119 return local.get().get(type);
120 }
121
122 final private Locale locale;
123 final private ConcurrentHashMap<Class, TranslationBundle> map = new ConcurrentHashMap<>();
124
125 private NLS(Locale locale) {
126 this.locale = locale;
127 }
128
129 @SuppressWarnings("unchecked")
130 private <T extends TranslationBundle> T get(Class<T> type) {
131 TranslationBundle bundle = map.get(type);
132 if (bundle == null) {
133 bundle = GlobalBundleCache.lookupBundle(locale, type);
134 // There is a small opportunity for a race, which we may
135 // lose. Accept defeat and return the winner's instance.
136 TranslationBundle old = map.putIfAbsent(type, bundle);
137 if (old != null)
138 bundle = old;
139 }
140 return (T) bundle;
141 }
142 }