org.sakaiproject.kernel.component.core.SharedClassLoaderContainer.java Source code

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Here is the source code for org.sakaiproject.kernel.component.core.SharedClassLoaderContainer.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.component.core;

import com.google.inject.Inject;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.sakaiproject.kernel.api.Kernel;
import org.sakaiproject.kernel.api.RequiresStop;
import org.sakaiproject.kernel.api.ShutdownService;
import org.sakaiproject.kernel.loader.common.CommonObject;

import java.lang.management.ManagementFactory;

import javax.management.Descriptor;
import javax.management.JMException;
import javax.management.JMRuntimeException;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.modelmbean.DescriptorSupport;
import javax.management.modelmbean.InvalidTargetObjectTypeException;
import javax.management.modelmbean.ModelMBeanAttributeInfo;
import javax.management.modelmbean.ModelMBeanInfo;
import javax.management.modelmbean.ModelMBeanInfoSupport;
import javax.management.modelmbean.ModelMBeanOperationInfo;
import javax.management.modelmbean.RequiredModelMBean;

/**
 * A container to hold the shared classloader for webapps as a bean.
 */
public class SharedClassLoaderContainer implements RequiresStop, CommonObject {

    /**
     * A logger.
     */
    private static final Log LOG = LogFactory.getLog(SharedClassLoaderContainer.class);
    private SharedClassLoader sharedClassLoader;

    /**
     * Create a shared classloader object.
     * 
     * @param kernel
     *          the kernel to connect to.
     * @param shutdownService
     *          the shutdown service.
     * @throws JMRuntimeException
     * @throws JMException
     * @throws InvalidTargetObjectTypeException
     */
    @Inject
    public SharedClassLoaderContainer(Kernel kernel, ShutdownService shutdownService, SharedClassLoader classLoader)
            throws JMRuntimeException, JMException, InvalidTargetObjectTypeException {
        this.sharedClassLoader = classLoader;
        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
        RequiredModelMBean model = new RequiredModelMBean(createMBeanInfo());
        model.setManagedResource(this, "objectReference");
        ObjectName common = new ObjectName(CommonObject.MBEAN_COMMON + ".sharedclassloader");
        mbs.registerMBean(model, common);

        // Explicit register this container to be shutdown, we dont want this
        // container exposed as a service, so we register directly. Within the
        // same module, this approach should be taken to give the IoC container
        // a dependency graph.
        shutdownService.register(this);
    }

    /**
     * Stop the classloader container, removing the MBean from the MBean server.
     * @see org.sakaiproject.kernel.api.RequiresStop#stop()
     */
    public void stop() {
        try {
            MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
            ObjectName common = new ObjectName(CommonObject.MBEAN_COMMON + ".sharedclassloader");
            mbs.unregisterMBean(common);
            LOG.info("Shared Classloader Container stopped Ok");
        } catch (JMException e) {
            LOG.debug(
                    "Cant stop the shared classloader bean, this will cause problems if the kernel is restarted in this jvm "
                            + e.getMessage(),
                    e);
        }
    }

    /**
     * Create the the MBean Info for the Shared ClassLoader so that the methods
     * and properties are accessible via JMX.
     * 
     * @return a new MBeanInfo structure
     */
    private ModelMBeanInfo createMBeanInfo() {
        Descriptor sharedClassLoader = new DescriptorSupport(
                new String[] { "name=SharedClassLoader", "descriptorType=attribute", "default=null",
                        "displayName=Shared Class Loader", "getMethod=getManagedObject" });

        ModelMBeanAttributeInfo[] mmbai = new ModelMBeanAttributeInfo[1];
        mmbai[0] = new ModelMBeanAttributeInfo("SharedClassLoader", ClassLoader.class.getName(),
                "Shared Class Loader", true, false, false, sharedClassLoader);

        ModelMBeanOperationInfo[] mmboi = new ModelMBeanOperationInfo[1];

        mmboi[0] = new ModelMBeanOperationInfo("getManagedObject", "Get the Shared Class Loader", null,
                ClassLoader.class.getName(), ModelMBeanOperationInfo.INFO);

        return new ModelMBeanInfoSupport(this.getClass().getName(), "Sakai Shared Classloader", mmbai, null, mmboi,
                null);
    }

    /**
     * Get the shared classloader..
     * @see org.sakaiproject.kernel.loader.common.CommonObject#getManagedObject()
     */
    @SuppressWarnings("unchecked")
    public <T> T getManagedObject() {
        return (T) sharedClassLoader;
    }

}