src/java.base/share/classes/java/util/spi/LocaleServiceProvider.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package java.util.spi;

 import java.util.Locale;

 /**
  * <p>
  * This is the super class of all the locale sensitive service provider
  * interfaces (SPIs).
  * <p>
  * Locale sensitive  service provider interfaces are interfaces that
  * correspond to locale sensitive classes in the <code>java.text</code>
  * and <code>java.util</code> packages. The interfaces enable the
  * construction of locale sensitive objects and the retrieval of
  * localized names for these packages. Locale sensitive factory methods
  * and methods for name retrieval in the <code>java.text</code> and
  * <code>java.util</code> packages use implementations of the provider
  * interfaces to offer support for locales beyond the set of locales
  * supported by the Java runtime environment itself.
  *
  * <h3>Packaging of Locale Sensitive Service Provider Implementations</h3>
  * Implementations of these locale sensitive services can be made available
  * by adding them to the application's class path. A provider identifies itself with a
  * provider-configuration file in the resource directory META-INF/services,
  * using the fully qualified provider interface class name as the file name.
  * The file should contain a list of fully-qualified concrete provider class names,
  * one per line. A line is terminated by any one of a line feed ('\n'), a carriage
  * return ('\r'), or a carriage return followed immediately by a line feed. Space
  * and tab characters surrounding each name, as well as blank lines, are ignored.
  * The comment character is '#' ('\u0023'); on each line all characters following
  * the first comment character are ignored. The file must be encoded in UTF-8.
  * <p>
  * If a particular concrete provider class is named in more than one configuration
  * file, or is named in the same configuration file more than once, then the
  * duplicates will be ignored. The configuration file naming a particular provider
  * need not be in the same jar file or other distribution unit as the provider itself.
  * The provider must be accessible from the same class loader that was initially
  * queried to locate the configuration file; this is not necessarily the class loader
  * that loaded the file.
  * <p>
  * For example, an implementation of the
  * {@link java.text.spi.DateFormatProvider DateFormatProvider} class should
  * take the form of a jar file which contains the file:
  * <pre>
  * META-INF/services/java.text.spi.DateFormatProvider
  * </pre>
  * And the file <code>java.text.spi.DateFormatProvider</code> should have
  * a line such as:
  * <pre>
  * <code>com.foo.DateFormatProviderImpl</code>
  * </pre>
  * which is the fully qualified class name of the class implementing
  * <code>DateFormatProvider</code>.
  * <h4>Invocation of Locale Sensitive Services</h4>
  * <p>
  * Locale sensitive factory methods and methods for name retrieval in the
  * <code>java.text</code> and <code>java.util</code> packages invoke
  * service provider methods when needed to support the requested locale.
  * The methods first check whether the Java runtime environment itself
  * supports the requested locale, and use its support if available.
  * Otherwise, they call the {@link #isSupportedLocale(Locale) isSupportedLocale}
  * methods of installed providers for the appropriate interface to find one that
  * supports the requested locale. If such a provider is found, its other
  * methods are called to obtain the requested object or name.  When checking
  * whether a locale is supported, the <a href="../Locale.html#def_extensions">
  * locale's extensions</a> are ignored by default. (If locale's extensions should
  * also be checked, the {@code isSupportedLocale} method must be overridden.)
  * If neither the Java runtime environment itself nor an installed provider
  * supports the requested locale, the methods go through a list of candidate
  * locales and repeat the availability check for each until a match is found.
  * The algorithm used for creating a list of candidate locales is same as
  * the one used by <code>ResourceBundle</code> by default (see
  * {@link java.util.ResourceBundle.Control#getCandidateLocales getCandidateLocales}
  * for the details).  Even if a locale is resolved from the candidate list,
  * methods that return requested objects or names are invoked with the original
  * requested locale including {@code Locale} extensions. The Java runtime
  * environment must support the root locale for all locale sensitive services in
  * order to guarantee that this process terminates.
  * <p>
  * Providers of names (but not providers of other objects) are allowed to
  * return null for some name requests even for locales that they claim to
  * support by including them in their return value for
  * <code>getAvailableLocales</code>. Similarly, the Java runtime
  * environment itself may not have all names for all locales that it
  * supports. This is because the sets of objects for which names are
  * requested can be large and vary over time, so that it's not always
  * feasible to cover them completely. If the Java runtime environment or a
  * provider returns null instead of a name, the lookup will proceed as
  * described above as if the locale was not supported.
  * <p>
  * The search order of locale sensitive services can
  * be configured by using the {@systemProperty java.locale.providers} system property.
  * This system property declares the user's preferred order for looking up
  * the locale sensitive services separated by a comma. It is only read at
  * the Java runtime startup, so the later call to System.setProperty() won't
  * affect the order.
  * <p>
  * Java Runtime Environment provides the following four locale providers:
  * <ul>
  * <li> "CLDR": A provider based on Unicode Consortium's
  * <a href="http://cldr.unicode.org/">CLDR Project</a>.
  * <li> "COMPAT": represents the locale sensitive services that is compatible
  * with the prior JDK releases up to JDK8 (same as JDK8's "JRE").
  * <li> "SPI": represents the locale sensitive services implementing the subclasses of
  * this {@code LocaleServiceProvider} class.
  * <li> "HOST": A provider that reflects the user's custom settings in the
  * underlying operating system. This provider may not be available, depending
  * on the Java Runtime Environment implementation.
  * <li> "JRE": represents a synonym to "COMPAT". This name
  * is deprecated and will be removed in the future release of JDK.
  * </ul>
  * <p>
  * For example, if the following is specified in the property:
  * <pre>
  * java.locale.providers=SPI,CLDR,COMPAT
  * </pre>
  * the locale sensitive services in the SPI providers are looked up first. If the
  * desired locale sensitive service is not available, then the runtime looks for CLDR,
  * COMPAT in that order.
  * <p>
  * The default order for looking up the preferred locale providers is "CLDR,COMPAT",
  * so specifying "CLDR,COMPAT" is identical to the default behavior. Applications which
  * require implementations of the locale sensitive services must explicitly specify
  * "SPI" in order for the Java runtime to load them from the classpath.
  *
  * @since        1.6
  */
 public abstract class LocaleServiceProvider {

     private static Void checkPermission() {
         SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
             sm.checkPermission(new RuntimePermission("localeServiceProvider"));
         }
         return null;
     }
     private LocaleServiceProvider(Void ignore) { }

     /**
      * Initializes a new locale service provider.
      *
      * @throws  SecurityException
      *          If a security manager has been installed and it denies
      *          {@link RuntimePermission RuntimePermission("localeServiceProvider")}
      */
     protected LocaleServiceProvider() {
         this(checkPermission());
     }

     /**
      * Returns an array of all locales for which this locale service provider
      * can provide localized objects or names. This information is used to
      * compose {@code getAvailableLocales()} values of the locale-dependent
      * services, such as {@code DateFormat.getAvailableLocales()}.
      *
      * <p>The array returned by this method should not include two or more
      * {@code Locale} objects only differing in their extensions.
      *
      * @return An array of all locales for which this locale service provider
      * can provide localized objects or names.
      */
     public abstract Locale[] getAvailableLocales();

     /**
      * Returns {@code true} if the given {@code locale} is supported by
      * this locale service provider. The given {@code locale} may contain
      * <a href="../Locale.html#def_extensions">extensions</a> that should be
      * taken into account for the support determination.
      *
      * <p>The default implementation returns {@code true} if the given {@code locale}
      * is equal to any of the available {@code Locale}s returned by
      * {@link #getAvailableLocales()} with ignoring any extensions in both the
      * given {@code locale} and the available locales. Concrete locale service
      * provider implementations should override this method if those
      * implementations are {@code Locale} extensions-aware. For example,
      * {@code DecimalFormatSymbolsProvider} implementations will need to check
      * extensions in the given {@code locale} to see if any numbering system is
      * specified and can be supported. However, {@code CollatorProvider}
      * implementations may not be affected by any particular numbering systems,
      * and in that case, extensions for numbering systems should be ignored.
      *
      * @param locale a {@code Locale} to be tested
      * @return {@code true} if the given {@code locale} is supported by this
      *         provider; {@code false} otherwise.
      * @throws NullPointerException
      *         if the given {@code locale} is {@code null}
      * @see Locale#hasExtensions()
      * @see Locale#stripExtensions()
      * @since 1.8
      */
     public boolean isSupportedLocale(Locale locale) {
         locale = locale.stripExtensions(); // throws NPE if locale == null
         for (Locale available : getAvailableLocales()) {
             if (locale.equals(available.stripExtensions())) {
                 return true;
 }
         }
         return false;
     }
 }
	/*
	* Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.util.spi;

	import java.util.Locale;

	/**
	* <p>
	* This is the super class of all the locale sensitive service provider
	* interfaces (SPIs).
	* <p>
	* Locale sensitive service provider interfaces are interfaces that
	* correspond to locale sensitive classes in the <code>java.text</code>
	* and <code>java.util</code> packages. The interfaces enable the
	* construction of locale sensitive objects and the retrieval of
	* localized names for these packages. Locale sensitive factory methods
	* and methods for name retrieval in the <code>java.text</code> and
	* <code>java.util</code> packages use implementations of the provider
	* interfaces to offer support for locales beyond the set of locales
	* supported by the Java runtime environment itself.
	*
	* <h3>Packaging of Locale Sensitive Service Provider Implementations</h3>
	* Implementations of these locale sensitive services can be made available
	* by adding them to the application's class path. A provider identifies itself with a
	* provider-configuration file in the resource directory META-INF/services,
	* using the fully qualified provider interface class name as the file name.
	* The file should contain a list of fully-qualified concrete provider class names,
	* one per line. A line is terminated by any one of a line feed ('\n'), a carriage
	* return ('\r'), or a carriage return followed immediately by a line feed. Space
	* and tab characters surrounding each name, as well as blank lines, are ignored.
	* The comment character is '#' ('\u0023'); on each line all characters following
	* the first comment character are ignored. The file must be encoded in UTF-8.
	* <p>
	* If a particular concrete provider class is named in more than one configuration
	* file, or is named in the same configuration file more than once, then the
	* duplicates will be ignored. The configuration file naming a particular provider
	* need not be in the same jar file or other distribution unit as the provider itself.
	* The provider must be accessible from the same class loader that was initially
	* queried to locate the configuration file; this is not necessarily the class loader
	* that loaded the file.
	* <p>
	* For example, an implementation of the
	* {@link java.text.spi.DateFormatProvider DateFormatProvider} class should
	* take the form of a jar file which contains the file:
	* <pre>
	* META-INF/services/java.text.spi.DateFormatProvider
	* </pre>
	* And the file <code>java.text.spi.DateFormatProvider</code> should have
	* a line such as:
	* <pre>
	* <code>com.foo.DateFormatProviderImpl</code>
	* </pre>
	* which is the fully qualified class name of the class implementing
	* <code>DateFormatProvider</code>.
	* <h4>Invocation of Locale Sensitive Services</h4>
	* <p>
	* Locale sensitive factory methods and methods for name retrieval in the
	* <code>java.text</code> and <code>java.util</code> packages invoke
	* service provider methods when needed to support the requested locale.
	* The methods first check whether the Java runtime environment itself
	* supports the requested locale, and use its support if available.
	* Otherwise, they call the {@link #isSupportedLocale(Locale) isSupportedLocale}
	* methods of installed providers for the appropriate interface to find one that
	* supports the requested locale. If such a provider is found, its other
	* methods are called to obtain the requested object or name. When checking
	* whether a locale is supported, the <a href="../Locale.html#def_extensions">
	* locale's extensions</a> are ignored by default. (If locale's extensions should
	* also be checked, the {@code isSupportedLocale} method must be overridden.)
	* If neither the Java runtime environment itself nor an installed provider
	* supports the requested locale, the methods go through a list of candidate
	* locales and repeat the availability check for each until a match is found.
	* The algorithm used for creating a list of candidate locales is same as
	* the one used by <code>ResourceBundle</code> by default (see
	* {@link java.util.ResourceBundle.Control#getCandidateLocales getCandidateLocales}
	* for the details). Even if a locale is resolved from the candidate list,
	* methods that return requested objects or names are invoked with the original
	* requested locale including {@code Locale} extensions. The Java runtime
	* environment must support the root locale for all locale sensitive services in
	* order to guarantee that this process terminates.
	* <p>
	* Providers of names (but not providers of other objects) are allowed to
	* return null for some name requests even for locales that they claim to
	* support by including them in their return value for
	* <code>getAvailableLocales</code>. Similarly, the Java runtime
	* environment itself may not have all names for all locales that it
	* supports. This is because the sets of objects for which names are
	* requested can be large and vary over time, so that it's not always
	* feasible to cover them completely. If the Java runtime environment or a
	* provider returns null instead of a name, the lookup will proceed as
	* described above as if the locale was not supported.
	* <p>
	* The search order of locale sensitive services can
	* be configured by using the {@systemProperty java.locale.providers} system property.
	* This system property declares the user's preferred order for looking up
	* the locale sensitive services separated by a comma. It is only read at
	* the Java runtime startup, so the later call to System.setProperty() won't
	* affect the order.
	* <p>
	* Java Runtime Environment provides the following four locale providers:
	* <ul>
	* <li> "CLDR": A provider based on Unicode Consortium's
	* <a href="http://cldr.unicode.org/">CLDR Project</a>.
	* <li> "COMPAT": represents the locale sensitive services that is compatible
	* with the prior JDK releases up to JDK8 (same as JDK8's "JRE").
	* <li> "SPI": represents the locale sensitive services implementing the subclasses of
	* this {@code LocaleServiceProvider} class.
	* <li> "HOST": A provider that reflects the user's custom settings in the
	* underlying operating system. This provider may not be available, depending
	* on the Java Runtime Environment implementation.
	* <li> "JRE": represents a synonym to "COMPAT". This name
	* is deprecated and will be removed in the future release of JDK.
	* </ul>
	* <p>
	* For example, if the following is specified in the property:
	* <pre>
	* java.locale.providers=SPI,CLDR,COMPAT
	* </pre>
	* the locale sensitive services in the SPI providers are looked up first. If the
	* desired locale sensitive service is not available, then the runtime looks for CLDR,
	* COMPAT in that order.
	* <p>
	* The default order for looking up the preferred locale providers is "CLDR,COMPAT",
	* so specifying "CLDR,COMPAT" is identical to the default behavior. Applications which
	* require implementations of the locale sensitive services must explicitly specify
	* "SPI" in order for the Java runtime to load them from the classpath.
	*
	* @since 1.6
	*/
	public abstract class LocaleServiceProvider {

	private static Void checkPermission() {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(new RuntimePermission("localeServiceProvider"));
	}
	return null;
	}
	private LocaleServiceProvider(Void ignore) { }

	/**
	* Initializes a new locale service provider.
	*
	* @throws SecurityException
	* If a security manager has been installed and it denies
	* {@link RuntimePermission RuntimePermission("localeServiceProvider")}
	*/
	protected LocaleServiceProvider() {
	this(checkPermission());
	}

	/**
	* Returns an array of all locales for which this locale service provider
	* can provide localized objects or names. This information is used to
	* compose {@code getAvailableLocales()} values of the locale-dependent
	* services, such as {@code DateFormat.getAvailableLocales()}.
	*
	* <p>The array returned by this method should not include two or more
	* {@code Locale} objects only differing in their extensions.
	*
	* @return An array of all locales for which this locale service provider
	* can provide localized objects or names.
	*/
	public abstract Locale[] getAvailableLocales();

	/**
	* Returns {@code true} if the given {@code locale} is supported by
	* this locale service provider. The given {@code locale} may contain
	* <a href="../Locale.html#def_extensions">extensions</a> that should be
	* taken into account for the support determination.
	*
	* <p>The default implementation returns {@code true} if the given {@code locale}
	* is equal to any of the available {@code Locale}s returned by
	* {@link #getAvailableLocales()} with ignoring any extensions in both the
	* given {@code locale} and the available locales. Concrete locale service
	* provider implementations should override this method if those
	* implementations are {@code Locale} extensions-aware. For example,
	* {@code DecimalFormatSymbolsProvider} implementations will need to check
	* extensions in the given {@code locale} to see if any numbering system is
	* specified and can be supported. However, {@code CollatorProvider}
	* implementations may not be affected by any particular numbering systems,
	* and in that case, extensions for numbering systems should be ignored.
	*
	* @param locale a {@code Locale} to be tested
	* @return {@code true} if the given {@code locale} is supported by this
	* provider; {@code false} otherwise.
	* @throws NullPointerException
	* if the given {@code locale} is {@code null}
	* @see Locale#hasExtensions()
	* @see Locale#stripExtensions()
	* @since 1.8
	*/
	public boolean isSupportedLocale(Locale locale) {
	locale = locale.stripExtensions(); // throws NPE if locale == null
	for (Locale available : getAvailableLocales()) {
	if (locale.equals(available.stripExtensions())) {
	return true;
	}
	}
	return false;
	}
	}