org.sakaiproject.kernel.loader.server.SwitchedClassLoader.java Source code

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Here is the source code for org.sakaiproject.kernel.loader.server.SwitchedClassLoader.java

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/*
 * Licensed to the Sakai Foundation (SF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The SF 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.sakaiproject.kernel.loader.server;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.net.URL;
import java.net.URLClassLoader;

/**
 *
 */
public class SwitchedClassLoader extends URLClassLoader {

    private static final Log LOG = LogFactory.getLog(SwitchedClassLoader.class);
    private static final boolean debug = LOG.isDebugEnabled();
    private ClassLoader containerClassloader;

    /**
     * @param giClassLoader
     */
    public SwitchedClassLoader(URL[] urls, ClassLoader parentClassLoader, ClassLoader containerClassloader) {
        super(urls, parentClassLoader);
        this.containerClassloader = containerClassloader;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
     */
    @Override
    protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        Class<?> c = findLoadedClass(name);
        ClassNotFoundException ex = null;

        if (c == null && containerClassloader != null) {
            try {
                c = containerClassloader.loadClass(name);
                if (debug)
                    LOG.debug("loaded " + c);
            } catch (ClassNotFoundException e) {
                ex = e;
            }
        }

        if (c == null) {
            try {
                c = this.findClass(name);
            } catch (ClassNotFoundException e) {
                ex = e;
            }
        }

        if (debug)
            LOG.debug("Resolved " + name + " as " + c);
        if (c == null)
            throw ex;

        if (resolve)
            resolveClass(c);

        if (debug)
            LOG.debug("loaded " + c + " from " + c.getClassLoader());

        return c;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.ClassLoader#getResource(java.lang.String)
     */
    @Override
    public URL getResource(String name) {
        URL url = null;
        url = containerClassloader.getResource(name);

        if (url == null) {
            url = this.findResource(name);

            if (url == null && name.startsWith("/")) {
                url = this.findResource(name.substring(1));
            }
        }

        return url;
    }
}