jaitools.lookup.Lookup Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2010 Michael Bedward
 *
 * This file is part of jai-tools.
 *
 * jai-tools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * jai-tools is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with jai-tools.  If not, see .
 *
 */

package jaitools.lookup;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

/**
 * This class offers minimal Service Provider Interface lookup functions.
 * Within jai-tools it is used to find implementations of non-operator interfaces
 * such as {@code jaitools.numeric.Processor}. Discovery of image operators
 * is done using the standard JAI mechanisms.
 *
 * @author Michael Bedward
 * @since 1.0
 * @source $URL: https://jai-tools.googlecode.com/svn/tags/1.0.0/utils/src/main/java/jaitools/lookup/Lookup.java $
 * @version $Id: Lookup.java 1100 2010-02-10 07:28:08Z michael.bedward $
 */
public class Lookup {

    private static final String prefix = "META-INF/services/";
    private static final Logger LOGGER = Logger.getLogger("jaitools.lookup");

    public static List getProviders(String spiName) {
        List providers = new ArrayList();

        InputStream str = ClassLoader.getSystemResourceAsStream(prefix + spiName);
        if (str != null) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(str));
            String line = null;

            try {
            while ((line = reader.readLine()) != null) {
                String text = line.trim();
                if (text.length() > 0 && !text.startsWith("#")) {
                    try {
                        providers.add(Class.forName(text));
                    } catch (ClassNotFoundException ex) {
                        LOGGER.warning("Class not found: " + text);
                    }
                }
            }} catch (IOException ex) {
                LOGGER.severe("Problem reading services file: " + spiName);
            }

            try {
                reader.close();
            } catch (IOException ex) {
                // ignore
            }
        }
        
        return providers;
    }
}