1 /*
2 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
66 * For example, an implementation of the
67 * {@link java.text.spi.DateFormatProvider DateFormatProvider} class should
68 * take the form of a jar file which contains the file:
69 * <pre>
70 * META-INF/services/java.text.spi.DateFormatProvider
71 * </pre>
72 * And the file <code>java.text.spi.DateFormatProvider</code> should have
73 * a line such as:
74 * <pre>
75 * <code>com.foo.DateFormatProviderImpl</code>
76 * </pre>
77 * which is the fully qualified class name of the class implementing
78 * <code>DateFormatProvider</code>.
79 * <h4>Invocation of Locale Sensitive Services</h4>
80 * <p>
81 * Locale sensitive factory methods and methods for name retrieval in the
82 * <code>java.text</code> and <code>java.util</code> packages invoke
83 * service provider methods when needed to support the requested locale.
84 * The methods first check whether the Java runtime environment itself
85 * supports the requested locale, and use its support if available.
86 * Otherwise, they call the <code>getAvailableLocales()</code> methods of
87 * installed providers for the appropriate interface to find one that
88 * supports the requested locale. If such a provider is found, its other
89 * methods are called to obtain the requested object or name. When checking
90 * whether a locale is supported, the locale's extensions are ignored.
91 * If neither the Java runtime environment itself nor an installed provider
92 * supports the requested locale, the methods go through a list of candidate
93 * locales and repeat the availability check for each until a match is found.
94 * The algorithm used for creating a list of candidate locales is same as
95 * the one used by <code>ResourceBunlde</code> by default (see
96 * {@link java.util.ResourceBundle.Control#getCandidateLocales getCandidateLocales}
97 * for the details). Even if a locale is resolved from the candidate list,
98 * methods that return requested objects or names are invoked with the original
99 * requested locale including extensions. The Java runtime environment must
100 * support the root locale for all locale sensitive services in order to
101 * guarantee that this process terminates.
102 * <p>
103 * Providers of names (but not providers of other objects) are allowed to
104 * return null for some name requests even for locales that they claim to
105 * support by including them in their return value for
106 * <code>getAvailableLocales</code>. Similarly, the Java runtime
107 * environment itself may not have all names for all locales that it
108 * supports. This is because the sets of objects for which names are
109 * requested can be large and vary over time, so that it's not always
110 * feasible to cover them completely. If the Java runtime environment or a
111 * provider returns null instead of a name, the lookup will proceed as
112 * described above as if the locale was not supported.
113 *
114 * @since 1.6
115 */
116 public abstract class LocaleServiceProvider {
117
118 /**
119 * Sole constructor. (For invocation by subclass constructors, typically
120 * implicit.)
121 */
122 protected LocaleServiceProvider() {
123 }
124
125 /**
126 * Returns an array of all locales for which this locale service provider
127 * can provide localized objects or names.
128 * <p>
129 * <b>Note:</b> Extensions in a <code>Locale</code> are ignored during
130 * service provider lookup. So the array returned by this method should
131 * not include two or more <code>Locale</code> objects only differing in
132 * their extensions.
133 *
134 * @return An array of all locales for which this locale service provider
135 * can provide localized objects or names.
136 */
137 public abstract Locale[] getAvailableLocales();
138 }
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1 /*
2 * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
66 * For example, an implementation of the
67 * {@link java.text.spi.DateFormatProvider DateFormatProvider} class should
68 * take the form of a jar file which contains the file:
69 * <pre>
70 * META-INF/services/java.text.spi.DateFormatProvider
71 * </pre>
72 * And the file <code>java.text.spi.DateFormatProvider</code> should have
73 * a line such as:
74 * <pre>
75 * <code>com.foo.DateFormatProviderImpl</code>
76 * </pre>
77 * which is the fully qualified class name of the class implementing
78 * <code>DateFormatProvider</code>.
79 * <h4>Invocation of Locale Sensitive Services</h4>
80 * <p>
81 * Locale sensitive factory methods and methods for name retrieval in the
82 * <code>java.text</code> and <code>java.util</code> packages invoke
83 * service provider methods when needed to support the requested locale.
84 * The methods first check whether the Java runtime environment itself
85 * supports the requested locale, and use its support if available.
86 * Otherwise, they call the {@link #isSupportedLocale(Locale) isSupportedLocale}
87 * methods of installed providers for the appropriate interface to find one that
88 * supports the requested locale. If such a provider is found, its other
89 * methods are called to obtain the requested object or name. When checking
90 * whether a locale is supported, the <a href="../Locale.html#def_extensions">
91 * locale's extensions</a> are ignored by default. (If locale's extensions should
92 * also be checked, the {@code isSupportedLocale} method must be overridden.)
93 * If neither the Java runtime environment itself nor an installed provider
94 * supports the requested locale, the methods go through a list of candidate
95 * locales and repeat the availability check for each until a match is found.
96 * The algorithm used for creating a list of candidate locales is same as
97 * the one used by <code>ResourceBunlde</code> by default (see
98 * {@link java.util.ResourceBundle.Control#getCandidateLocales getCandidateLocales}
99 * for the details). Even if a locale is resolved from the candidate list,
100 * methods that return requested objects or names are invoked with the original
101 * requested locale including {@code Locale} extensions. The Java runtime
102 * environment must support the root locale for all locale sensitive services in
103 * order to guarantee that this process terminates.
104 * <p>
105 * Providers of names (but not providers of other objects) are allowed to
106 * return null for some name requests even for locales that they claim to
107 * support by including them in their return value for
108 * <code>getAvailableLocales</code>. Similarly, the Java runtime
109 * environment itself may not have all names for all locales that it
110 * supports. This is because the sets of objects for which names are
111 * requested can be large and vary over time, so that it's not always
112 * feasible to cover them completely. If the Java runtime environment or a
113 * provider returns null instead of a name, the lookup will proceed as
114 * described above as if the locale was not supported.
115 * <p>
116 * Starting from JDK8, the search order of locale sensitive services can
117 * be configured by using the "java.locale.providers" system property.
118 * This system property declares the user's preferred order for looking up
119 * the locale sensitive services separated by a comma. It is only read at
120 * the Java runtime startup, so the later call to System.setProperty() won't
121 * affect the order.
122 * <p>
123 * For example, if the following is specified in the property:
124 * <pre>
125 * java.locale.providers=SPI,JRE
126 * </pre>
127 * where "SPI" represents the locale sensitive services implemented in the
128 * installed SPI providers, and "JRE" represents the locale sensitive services
129 * in the Java Runtime Environment, the locale sensitive services in the SPI
130 * providers are looked up first.
131 *
132 * @since 1.6
133 */
134 public abstract class LocaleServiceProvider {
135
136 /**
137 * Sole constructor. (For invocation by subclass constructors, typically
138 * implicit.)
139 */
140 protected LocaleServiceProvider() {
141 }
142
143 /**
144 * Returns an array of all locales for which this locale service provider
145 * can provide localized objects or names. This information is used to
146 * compose {@code getAvailableLocales()} values of the locale-dependent
147 * services, such as {@code DateFormat.getAvailableLocales()}.
148 *
149 * <p>The array returned by this method should not include two or more
150 * {@code Locale} objects only differing in their extensions.
151 *
152 * @return An array of all locales for which this locale service provider
153 * can provide localized objects or names.
154 */
155 public abstract Locale[] getAvailableLocales();
156
157 /**
158 * Returns {@code true} if the given {@code locale} is supported by
159 * this locale service provider. The given {@code locale} may contain
160 * <a href="../Locale.html#def_extensions">extensions<a/> that should be
161 * taken into account for the support determination.
162 *
163 * <p>The default implementation returns {@code true} if the given {@code locale}
164 * is equal to any of the available {@code Locale}s returned by
165 * {@link #getAvailableLocales()} with ignoring any extensions in both the
166 * given {@code locale} and the available locales. Concrete locale service
167 * provider implementations should override this method if those
168 * implementations are {@code Locale} extensions-aware. For example,
169 * {@code DecimalFormatSymbolsProvider} implementations will need to check
170 * extensions in the given {@code locale} to see if any numbering system is
171 * specified and can be supported. However, {@code CollatorProvider}
172 * implementations may not be affected by any particular numbering systems,
173 * and in that case, extensions for numbering systems should be ignored.
174 *
175 * @param locale a {@code Locale} to be tested
176 * @return {@code true} if the given {@code locale} is supported by this
177 * provider; {@code false} otherwise.
178 * @throws NullPointerException
179 * if the given {@code locale} is {@code null}
180 * @see Locale#hasExtensions()
181 * @see Locale#stripExtensions()
182 * @since 1.8
183 */
184 public boolean isSupportedLocale(Locale locale) {
185 locale = locale.stripExtensions(); // throws NPE if locale == null
186 for (Locale available : getAvailableLocales()) {
187 if (locale.equals(available.stripExtensions())) {
188 return true;
189 }
190 }
191 return false;
192 }
193 }
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