Fix OPENDJ-346 Consider using java.util.ServiceLoader for loading extension...

Nicolas Capponi

08.16.2013 f2090c0d863b07e3bad8d16a3efddfad6ff77960

 opendj3/opendj-ldap-sdk/src/main/java/com/forgerock/opendj/util/StaticUtils.java

@@ -45,6 +45,7 @@
import java.util.GregorianCalendar;
import java.util.Iterator;
import java.util.Locale;
import java.util.ServiceLoader;
import java.util.TimeZone;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
@@ -60,6 +61,8 @@
import org.forgerock.i18n.LocalizableMessageBuilder;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.opendj.ldap.ProviderNotFoundException;
import org.forgerock.opendj.ldap.spi.Provider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@@ -2256,4 +2259,47 @@
        // No implementation required.
    }

    /**
     * Find and returns a provider of one or more implementations.
     * <p>
     * The provider is loaded using the {@code ServiceLoader} facility.
     *
     * @param <P> type of provider
     * @param providerClass
     *          class of provider
     * @param requestedProvider
     *            name of provider to use, or {@code null} if no specific
     *            provider is requested.
     * @param classLoader
     *            class loader to use to load the provider, or {@code null} to
     *            use the default class loader.
     * @return a provider
     * @throws ProviderNotFoundException
     *             if no provider is available or if the provider requested
     *             using options is not found.
     */
    public static <P extends Provider> P getProvider(final Class<P> providerClass, final String requestedProvider,
            final ClassLoader classLoader) {

        ServiceLoader<P> loader = ServiceLoader.load(providerClass, classLoader);
        StringBuilder providersFound = new StringBuilder();
        for (P provider : loader) {
            if (providersFound.length() > 0) {
                providersFound.append(" ");
            }
            providersFound.append(provider.getName());
            if (requestedProvider == null || provider.getName().equals(requestedProvider)) {
                return provider;
            }
        }
        if (providersFound.length() > 0) {
            throw new ProviderNotFoundException(providerClass, requestedProvider, String.format(
                    "The requested provider '%s' of type '%s' was not found. Available providers: %s",
                    requestedProvider, providerClass.getName(), providersFound));
        } else {
            throw new ProviderNotFoundException(providerClass, requestedProvider, String.format(
                    "There was no provider of type '%s' available.", providerClass.getName()));
        }
    }

}