org.sakaiproject.kernel.loader.server.jetty.SakaiWebAppContext.java Source code

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Here is the source code for org.sakaiproject.kernel.loader.server.jetty.SakaiWebAppContext.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.jetty;

import edu.umd.cs.findbugs.annotations.SuppressWarnings;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.mortbay.jetty.webapp.WebAppClassLoader;
import org.mortbay.jetty.webapp.WebAppContext;
import org.mortbay.resource.Resource;
import org.sakaiproject.kernel.loader.common.CommonObjectConfigurationException;
import org.sakaiproject.kernel.loader.common.CommonObjectManager;
import org.sakaiproject.kernel.loader.server.SwitchedClassLoader;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 *
 */
public class SakaiWebAppContext extends WebAppContext {
    private static final Log LOG = LogFactory.getLog(SakaiWebAppContext.class);
    private static final boolean debug = LOG.isDebugEnabled();
    private ClassLoader parentClassloader = null;
    private WebAppClassLoader webappClassLoader = null;
    private Object lock = new Object();
    private ClassLoader containerClassLoader;

    /**
     * @throws CommonObjectConfigurationException
     * @throws IOException
     * 
     */
    public SakaiWebAppContext(ClassLoader containerClassLoader)
            throws CommonObjectConfigurationException, IOException {
        this.containerClassLoader = containerClassLoader;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.mortbay.jetty.handler.ContextHandler#getClassLoader()
     */
    @Override
    @SuppressWarnings(value = "DC_DOUBLECHECK", justification = "Double checking in this instance avoids excessive use of the sunchronized lock as the variable is immutable once set")
    public ClassLoader getClassLoader() {
        if (webappClassLoader == null) {
            synchronized (lock) {
                if (webappClassLoader == null) {
                    try {

                        CommonObjectManager com = new CommonObjectManager("sharedclassloader");
                        final ClassLoader cl = com.getManagedObject();
                        parentClassloader = AccessController
                                .doPrivileged(new PrivilegedAction<SwitchedClassLoader>() {

                                    public SwitchedClassLoader run() {
                                        return new SwitchedClassLoader(new URL[] {}, cl, containerClassLoader);
                                    }

                                });

                        LOG.info("Got Classloader fromm JMX as " + parentClassloader + "("
                                + parentClassloader.getClass() + ")");
                        if (debug) {
                            LOG.debug("Thread Context class loader is: " + parentClassloader);
                            ClassLoader loader = parentClassloader.getParent();
                            while (loader != null) {
                                LOG.debug("Parent class loader is: " + loader);
                                loader = loader.getParent();
                            }
                        }

                        webappClassLoader = AccessController
                                .doPrivileged(new PrivilegedAction<WebAppClassLoader>() {

                                    public WebAppClassLoader run() {
                                        try {
                                            return new WebAppClassLoader(parentClassloader,
                                                    SakaiWebAppContext.this);
                                        } catch (IOException e) {
                                            throw new AccessControlException(
                                                    "Unable to start classloader cause:" + e.getMessage());
                                        }
                                    }

                                });
                        super.setClassLoader(webappClassLoader);
                    } catch (CommonObjectConfigurationException e) {
                        LOG.error(e);
                    }
                }
            }
        }
        return webappClassLoader;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.mortbay.jetty.webapp.WebAppContext#setWar(java.lang.String)
     */
    @Override
    public void setWar(String war) {
        try {
            Resource r = Resource.newResource(war);
            LOG.info("Resource " + r);
        } catch (MalformedURLException e) {
            LOG.info("Resource Error " + e.getMessage(), e);
        } catch (IOException e) {
            LOG.info("Resource Error " + e.getMessage(), e);
        }
        super.setWar(war);
    }
}