ca.phon.util.resources.ClassLoaderHandler.java Source code

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Here is the source code for ca.phon.util.resources.ClassLoaderHandler.java

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/*
 * Phon - An open source tool for research in phonology.
 * Copyright (C) 2005 - 2015, Gregory Hedlund <ghedlund@mun.ca> and Yvan Rose <yrose@mun.ca>
 * Dept of Linguistics, Memorial University <https://phon.ca>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package ca.phon.util.resources;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Logger;

import org.apache.commons.lang3.StringUtils;

/**
 * Loads resources from a specified class loader (or the
 * default class loader if not specified.)
 * 
 * Resources are located using {@link ClassLoader#getResources(String)}
 * for each specified resource.
 */
public abstract class ClassLoaderHandler<T> extends URLHandler<T> {

    private static final Logger LOGGER = Logger.getLogger(ClassLoaderHandler.class.getName());

    /**
     * Class loader
     */
    private ClassLoader classLoader = getClass().getClassLoader();

    /**
     * Resources to load
     */
    public List<String> resourcePaths = new ArrayList<String>();

    /**
     * Constructor
     */
    public ClassLoaderHandler() {
    }

    /**
     * Constructor
     * 
     * @param cl the classloader to use
     */
    public ClassLoaderHandler(ClassLoader cl) {
        this.classLoader = cl;
    }

    /**
     * Add a resource to locate
     * 
     * @param res the resource to locate.  Use the naming rules
     *  outline by {@link ClassLoader#getResource(String)}.
     */
    public void addResource(String res) {
        this.resourcePaths.add(res);
    }

    /**
     * Load resource list from the give resource file.
     * 
     * @param file
     */
    public void loadResourceFile(String resFile) {
        try {
            final Enumeration<URL> resURLS = getClassLoader().getResources(resFile);
            while (resURLS.hasMoreElements()) {
                final URL resURL = resURLS.nextElement();

                // open file and read in one url at a time
                final BufferedReader in = new BufferedReader(new InputStreamReader(resURL.openStream()));
                String line = null;
                while ((line = in.readLine()) != null) {
                    final String resVal = StringUtils.strip(line);
                    if (resVal.length() > 0) {
                        addResource(resVal);
                    }
                }
                in.close();
            }
        } catch (IOException e) {
            LOGGER.severe(e.getMessage());
        }
    }

    /**
     * Remove resource
     * 
     * @param res
     */
    public void removeResource(String res) {
        this.resourcePaths.remove(res);
    }

    @Override
    public Iterator<T> iterator() {
        super.getURLS().clear();
        for (String res : resourcePaths) {

            try {
                Enumeration<URL> resURLS = getClassLoader().getResources(res);
                while (resURLS.hasMoreElements()) {
                    super.add(resURLS.nextElement());
                }

            } catch (IOException e) {
                e.printStackTrace();
                LOGGER.severe(e.getMessage());
            }

        }

        return super.iterator();
    }

    /**
     * Get the class loader used by this handler.
     * 
     * @return ClassLoader
     */
    public ClassLoader getClassLoader() {
        return this.classLoader;
    }

    /**
     * Set the class loader used by this handler.
     * 
     * @param cl the new class loader to use, if <code>null</code>
     *  the default system classloader is used
     */
    public void setClassLoader(ClassLoader cl) {
        this.classLoader = (cl == null ? getClass().getClassLoader() : cl);
    }

}