| /* |
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| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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| * |
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| |
| 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 are packaged using the |
| * <a href="../../../../technotes/guides/extensions/index.html">Java Extension Mechanism</a> |
| * as installed extensions. 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> |
| * Starting from JDK8, the search order of locale sensitive services can |
| * be configured by using the "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> |
| * For example, if the following is specified in the property: |
| * <pre> |
| * java.locale.providers=SPI,JRE |
| * </pre> |
| * where "SPI" represents the locale sensitive services implemented in the |
| * installed SPI providers, and "JRE" represents the locale sensitive services |
| * in the Java Runtime Environment, the locale sensitive services in the SPI |
| * providers are looked up first. |
| * <p> |
| * There are two other possible locale sensitive service providers, i.e., "CLDR" |
| * which is a provider based on Unicode Consortium's |
| * <a href="http://cldr.unicode.org/">CLDR Project</a>, and "HOST" which is a |
| * provider that reflects the user's custom settings in the underlying operating |
| * system. These two providers may not be available, depending on the Java Runtime |
| * Environment implementation. Specifying "JRE,SPI" is identical to the default |
| * behavior, which is compatibile with the prior releases. |
| * |
| * @since 1.6 |
| */ |
| public abstract class LocaleServiceProvider { |
| |
| /** |
| * Sole constructor. (For invocation by subclass constructors, typically |
| * implicit.) |
| */ |
| protected LocaleServiceProvider() { |
| } |
| |
| /** |
| * 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; |
| } |
| } |