* This is the super class of all the locale sensitive service provider * interfaces (SPIs). *
* Locale sensitive service provider interfaces are interfaces that
* correspond to locale sensitive classes in the java.text
* and java.util 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 java.text and
* java.util packages use implementations of the provider
* interfaces to offer support for locales beyond the set of locales
* supported by the Java runtime environment itself.
*
*
* 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. *
* 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: *
* META-INF/services/java.text.spi.DateFormatProvider ** And the file
java.text.spi.DateFormatProvider should have
* a line such as:
*
* com.foo.DateFormatProviderImpl
*
* which is the fully qualified class name of the class implementing
* DateFormatProvider.
*
* Locale sensitive factory methods and methods for name retrieval in the
* java.text and java.util 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 getAvailableLocales() 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 locale's extensions are ignored.
* 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 ResourceBunlde 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 extensions. The Java runtime environment must
* support the root locale for all locale sensitive services in order to
* guarantee that this process terminates.
*
* 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
* getAvailableLocales. 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.
*
* @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.
*
* Note: Extensions in a Locale are ignored during
* service provider lookup. So the array returned by this method should
* not include two or more 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();
}