* {@code ResourceBundleProvider} is a service provider interface for

 * resource bundles. It is used by

 * {@link ResourceBundle#getBundle(String) ResourceBundle.getBundle}

 * factory methods to locate and load the service providers that are deployed as

 * modules via {@link java.util.ServiceLoader ServiceLoader}.

 *

 * <h3>Developing resource bundle services</h3>

 * A service for a resource bundle of a given <em>{@code baseName}</em> must have

 * a fully-qualified class name of the form:

 * <blockquote>

 * {@code <package of baseName> + ".spi." + <simple name of baseName> + "Provider"}

 * </blockquote>

 *

 * The service type is in a {@code spi} subpackage as it may be packaged in

 * a module separate from the resource bundle providers.

 * For example, the service for a resource bundle named

 * {@code com.example.app.MyResources} must be

 * {@code com.example.app.spi.MyResourcesProvider}:

 *

 * <blockquote><pre>

 * {@code package com.example.app.spi;

 * }</pre></blockquote>

 *

 * <h3>Deploying resource bundle service providers</h3>

 *

 * Resource bundles can be deployed in one or more service providers

 * in modules.  For example, a provider for a service

 * named "{@code com.example.app.spi.MyResourcesProvider}"

 * has the following implementation class:

 *

 * <blockquote><pre>

 * {@code import com.example.app.spi.MyResourcesProvider;

 * class MyResourcesProviderImpl extends AbstractResourceBundleProvider

 *     implements MyResourcesProvider

 * {

 *     public MyResourcesProviderImpl() {

 *         super("java.properties");

 *     }

 *     // this provider maps the resource bundle to per-language package

 *     protected String toBundleName(String baseName, Locale locale) {

 *         return "p." + locale.getLanguage() + "." + baseName;

 *     }

 *

 *     public ResourceBundle getBundle(String baseName, Locale locale) {

 *         // this module only provides bundles in French

 *         if (locale.equals(Locale.FRENCH)) {

 *              return super.getBundle(baseName, locale);

 *         }

 *         // otherwise return null

 *         return null;

 *     }

 * }}</pre></blockquote>

 *

 * This example provides "{@code com.example.app.MyResources}"

 * resource bundle of the French locale.  Traditionally resource bundles of

 * all locales are packaged in the same package as the resource bundle base name.

 * When deploying resource bundles in more than one modules and two modules

 * containing a package of the same name, <em>split package</em>,

 * is not supported, resource bundles in each module can be packaged in

 * a different package as shown in this example where this provider packages

 * the resource bundles in per-language package, i.e. {@code com.example.app.fr}

 * for French locale.

 * <p> A provider can provide more than one services, each of which is a service

 * for a resource bundle of a different base name.

 *

 * <p>{@link AbstractResourceBundleProvider}

 * provides the basic implementation for {@code ResourceBundleProvider}

 * and a subclass can override the {@link

 * AbstractResourceBundleProvider#toBundleName(String, Locale) toBundleName}

 * method to return a provider-specific location of the resource to be loaded,

 * for example, per-language package.

 * A provider can override {@link #getBundle ResourceBundleProvider.getBundle}

 * method for example to only search the known supported locales or

 * return resource bundles in other formats such as XML.

 *

 * <p>The module declaration of this provider module specifies the following

 * directive:

 * <pre>

 *     provides com.example.app.spi.MyResourcesProvider with com.example.impl.MyResourcesProviderImpl;

 * </pre>

 *

 * <h3><a id="obtain-resource-bundle">Obtaining resource bundles from providers</a></h3>

 * The module declaration of the <em>consumer module</em> that calls one of the

 * {@code ResourceBundle.getBundle} factory methods to obtain a resource

 * bundle from service providers must specify the following directive:

 * <pre>

 *     uses com.example.app.spi.MyResourcesProvider;

 * </pre>

 *

 * {@link ResourceBundle#getBundle(String, Locale)

 * ResourceBundle.getBundle("com.example.app.MyResource", locale)}

 * locates and loads the providers for {@code com.example.app.spi.MyResourcesProvider}

 * service and then invokes {@link #getBundle(String, Locale)

 * ResourceBundleProvider.getBundle("com.example.app.MyResource", locale)} to

 * find the resource bundle of the given base name and locale.

 * If the consumer module is a resource bundle service provider for

 * {@code com.example.app.spi.MyResourcesProvider}, {@code ResourceBundle.getBundle}

 * will locate resource bundles only from service providers.

 * Otherwise, {@code ResourceBundle.getBundle} may continue the search of

 * the resource bundle in other modules and class path per the specification

 * of the {@code ResourceBundle.getBundle} method being called.

 *

 * @see AbstractResourceBundleProvider

 * @see <a href="../ResourceBundle.html#resource-bundle-modules">

 *      Resource Bundles and Named Modules</a>

 * @see java.util.ServiceLoader