RepositoryClassLoader.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.components.classloader;

import org.apache.avalon.framework.logger.LogEnabled;
import org.apache.avalon.framework.logger.Logger;

import org.apache.cocoon.CascadingIOException;
import org.apache.cocoon.util.ClassUtils;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collection;
import java.util.Iterator;
import java.util.Vector;

/**
 * A class loader with a growable list of path search directories.
 * BL: Changed to extend URLClassLoader for both maintenance and
 *     compatibility reasons.  It doesn't hurt that it runs quicker
 *     now as well.
 *
 * @author <a href="mailto:ricardo@apache.org">Ricardo Rocha</a>
 * @author <a href="mailto:bloritsch@apache.org">Berin Loritsch</a>
 * @version $Id$
 */
public class RepositoryClassLoader extends URLClassLoader
                                   implements LogEnabled {

    /**
     * The logger
     */
    protected Logger log;

    /**
     * Create an empty new class loader.
     */
    public RepositoryClassLoader() {
        super(new URL[]{}, ClassUtils.getClassLoader());
    }

    /**
     * Create an empty new class loader.
     */
    public RepositoryClassLoader(URL[] urls) {
        super(urls, ClassUtils.getClassLoader());
    }

    /**
     * Create an empty new class loader.
     */
    public RepositoryClassLoader(URL[] urls, ClassLoader parentClassLoader) {
        super(urls, parentClassLoader);
    }

    /**
     * Create a class loader from a list of directories
     *
     * @param repositories List of searchable directories
     */
    protected RepositoryClassLoader(Vector repositories) {
        this((Collection) repositories);
    }

    /**
     * Create a class loader from a list of directories
     *
     * @param repositories List of searchable directories
     */
    protected RepositoryClassLoader(Collection repositories) {
        this();
        Iterator i = repositories.iterator();
        while (i.hasNext()) {
            try {
                this.addDirectory((File) i.next());
            } catch (IOException ioe) {
                log.error("Repository could not be added", ioe);
            }
        }
    }

    /**
     * Provide component with a logger.
     *
     * @param logger the logger
     */
    public void enableLogging(Logger logger) {
        if (this.log == null) {
            this.log = logger;
        }
    }

    /**
     * Add a directory to the list of searchable repositories. This methods ensures that no directory is specified more
     * than once.
     *
     * @param repository The directory path
     * @throws IOException Non-existent, non-readable or non-directory repository
     */
    public void addDirectory(File repository) throws IOException {
        try {
            this.addURL(repository.getCanonicalFile().toURL());
        } catch (MalformedURLException mue) {
            log.error("The repository had a bad URL", mue);
            throw new CascadingIOException("Could not add repository", mue);
        }
    }

    /**
     * Add a directory to the list of searchable repositories. This methods ensures that no directory is specified more
     * than once.
     *
     * @param repository The directory path
     * @throws IOException Non-existent, non-readable or non-directory repository
     */
    public void addDirectory(String repository) throws IOException {
        try {
            File file = new File(repository);
            this.addURL(file.getCanonicalFile().toURL());
        } catch (MalformedURLException mue) {
            log.error("The repository had a bad URL", mue);
            throw new CascadingIOException("Could not add repository", mue);
        }
    }

    /**
     * Add a url to the list of searchable repositories
     */
    public void addURL(URL url) {
        super.addURL(url);
    }

    /**
     * Create a Class from a byte array
     */
    public Class defineClass(byte[] b) throws ClassFormatError {
        return super.defineClass(null, b, 0, b.length);
    }
}