org.ops4j.pax.web.jsp.internal.JasperClassLoader.java Source code

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Here is the source code for org.ops4j.pax.web.jsp.internal.JasperClassLoader.java

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/* Copyright 2008 Alin Dreghiciu.
 *
 * Licensed 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.ops4j.pax.web.jsp.internal;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.osgi.framework.Bundle;
import org.ops4j.pax.swissbox.core.BundleClassLoader;

/**
 * Jasper enforces a URLClassLoader so he can lookup the jars in order to get the TLDs.
 * This class loader will use the Bundle-ClassPath to get the list of classloaders and delegate class loading to a
 * bundle class loader.
 *
 * @author Alin Dreghiciu
 * @since 0.3.0 January 08, 2008
 */
public final class JasperClassLoader extends URLClassLoader {

    /**
     * Internal bundle class loader.
     */
    private final BundleClassLoader m_bundleClassLoader;

    /**
     * Logger.
     */
    private static final Log LOG = LogFactory.getLog(JasperClassLoader.class);

    public JasperClassLoader(final Bundle bundle, final ClassLoader parent) {
        super(getClassPathJars(bundle));
        m_bundleClassLoader = new BundleClassLoader(bundle, parent);
    }

    /**
     * Delegate to bundle class loader.
     *
     * @see BundleClassLoader#getResource(String)
     */
    public URL getResource(String name) {
        return m_bundleClassLoader.getResource(name);
    }

    /**
     * Delegate to bundle class loader.
     *
     * @see BundleClassLoader#getResources(String)
     */
    public Enumeration<URL> getResources(String name) throws IOException {
        return m_bundleClassLoader.getResources(name);
    }

    /**
     * Delegate to bundle class loader.
     *
     * @see BundleClassLoader#loadClass(String)
     */
    public Class loadClass(final String name) throws ClassNotFoundException {
        return m_bundleClassLoader.loadClass(name);
    }

    @Override
    public String toString() {
        return new StringBuffer().append(this.getClass().getSimpleName()).append("{").append("bundleClassLoader=")
                .append(m_bundleClassLoader).append("}").toString();
    }

    /**
     * Returns a list of urls to jars that composes the Bundle-ClassPath.
     *
     * @param bundle the bundle from which the class path should be taken
     *
     * @return list or urls to jars that composes the Bundle-ClassPath.
     */
    private static URL[] getClassPathJars(final Bundle bundle) {
        final List<URL> urls = new ArrayList<URL>();
        final String bundleClasspath = (String) bundle.getHeaders().get("Bundle-ClassPath");
        if (bundleClasspath != null) {
            String[] segments = bundleClasspath.split(",");
            for (String segment : segments) {
                final URL url = bundle.getEntry(segment);
                if (url != null) {
                    if (url.toExternalForm().endsWith("jar")) {
                        LOG.debug("Using url: " + url);
                        try {
                            URL jarUrl = new URL("jar:" + url.toExternalForm() + "!/");
                            urls.add(jarUrl);
                        } catch (MalformedURLException ignore) {
                            LOG.debug(ignore.getMessage());
                        }
                    }
                }
            }
        }
        LOG.debug("Bundle-ClassPath URLs: " + urls);
        return urls.toArray(new URL[urls.size()]);
    }

}