GpgSignatureVerifierFactory.java

/*
 * Copyright (C) 2021, 2022 Thomas Wolf <thomas.wolf@paranor.ch> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.lib;

import java.util.Iterator;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A {@code GpgSignatureVerifierFactory} creates {@link GpgSignatureVerifier} instances.
 *
 * @since 5.11
 */
public abstract class GpgSignatureVerifierFactory {

    private static final Logger LOG = LoggerFactory
            .getLogger(GpgSignatureVerifierFactory.class);

    private static class DefaultFactory {

        private static volatile GpgSignatureVerifierFactory defaultFactory = loadDefault();

        private static GpgSignatureVerifierFactory loadDefault() {
            try {
                ServiceLoader<GpgSignatureVerifierFactory> loader = ServiceLoader
                        .load(GpgSignatureVerifierFactory.class);
                Iterator<GpgSignatureVerifierFactory> iter = loader.iterator();
                if (iter.hasNext()) {
                    return iter.next();
                }
            } catch (ServiceConfigurationError e) {
                LOG.error(e.getMessage(), e);
            }
            return null;
        }

        private DefaultFactory() {
            // No instantiation
        }

        public static GpgSignatureVerifierFactory getDefault() {
            return defaultFactory;
        }

        /**
         * Sets the default factory.
         *
         * @param factory
         *            the new default factory
         */
        public static void setDefault(GpgSignatureVerifierFactory factory) {
            defaultFactory = factory;
        }
    }

    /**
     * Retrieves the default factory.
     *
     * @return the default factory or {@code null} if none set
     */
    public static GpgSignatureVerifierFactory getDefault() {
        return DefaultFactory.getDefault();
    }

    /**
     * Sets the default factory.
     *
     * @param factory
     *            the new default factory
     */
    public static void setDefault(GpgSignatureVerifierFactory factory) {
        DefaultFactory.setDefault(factory);
    }

    /**
     * Creates a new {@link GpgSignatureVerifier}.
     *
     * @return the new {@link GpgSignatureVerifier}
     */
    public abstract GpgSignatureVerifier getVerifier();

}