Commons Modeler example source code file (BaseAttributeFilter.java)

This example Commons Modeler source code file (BaseAttributeFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Modeler tags/keywords

attributechangenotification, attributechangenotification, baseattributefilter, baseattributefilter, hashset, hashset, management, notificationfilter, string, string, util

The Commons Modeler BaseAttributeFilter.java source code

/*
 * 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.commons.modeler;


import java.util.HashSet;

import javax.management.AttributeChangeNotification;
import javax.management.Notification;
import javax.management.NotificationFilter;


/**
 * <p>Implementation of NotificationFilter for attribute change
 * notifications.  This class is used by <code>BaseModelMBean to
 * construct attribute change notification event filters when a filter is not
 * supplied by the application.</p>
 *
 * @author Craig R. McClanahan
 * @version $Revision: 480402 $ $Date: 2006-11-29 04:43:23 +0000 (Wed, 29 Nov 2006) $
 */

public class BaseAttributeFilter implements NotificationFilter {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new filter that accepts only the specified attribute
     * name.
     *
     * @param name Name of the attribute to be accepted by this filter, or
     *  <code>null to accept all attribute names
     */
    public BaseAttributeFilter(String name) {

        super();
        if (name != null)
            addAttribute(name);

    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The set of attribute names that are accepted by this filter.  If this
     * list is empty, all attribute names are accepted.
     */
    private HashSet names = new HashSet();


    // --------------------------------------------------------- Public Methods


    /**
     * Add a new attribute name to the set of names accepted by this filter.
     *
     * @param name Name of the attribute to be accepted
     */
    public void addAttribute(String name) {

        synchronized (names) {
            names.add(name);
        }

    }


    /**
     * Clear all accepted names from this filter, so that it will accept
     * all attribute names.
     */
    public void clear() {

        synchronized (names) {
            names.clear();
        }

    }


    /**
     * Return the set of names that are accepted by this filter.  If this
     * filter accepts all attribute names, a zero length array will be
     * returned.
     */
    public String[] getNames() {

        synchronized (names) {
            return ((String[]) names.toArray(new String[names.size()]));
        }

    }


    /**
     * <p>Test whether notification enabled for this event.
     * Return true if:</p>
     * <ul>
     * <li>This is an attribute change notification
     * <li>Either the set of accepted names is empty (implying that all
     *     attribute names are of interest) or the set of accepted names
     *     includes the name of the attribute in this notification</li>
     * </ul>
     */
    public boolean isNotificationEnabled(Notification notification) {

        if (notification == null)
            return (false);
        if (!(notification instanceof AttributeChangeNotification))
            return (false);
        AttributeChangeNotification acn =
            (AttributeChangeNotification) notification;
        if (!AttributeChangeNotification.ATTRIBUTE_CHANGE.equals(acn.getType()))
            return (false);
        synchronized (names) {
            if (names.size() < 1)
                return (true);
            else
                return (names.contains(acn.getAttributeName()));
        }

    }


    /**
     * Remove an attribute name from the set of names accepted by this
     * filter.
     *
     * @param name Name of the attribute to be removed
     */
    public void removeAttribute(String name) {

        synchronized (names) {
            names.remove(name);
        }

    }


}