PropertyEventDispatcher.java 3.91 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright 2004 Jive Software.
 *
 * All rights reserved. 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.
 */

21
package org.jivesoftware.util;
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137

import org.jivesoftware.util.Log;

import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Dispatches property events. Each event has a {@link EventType type}
 * and optional parameters, as follows:<p>
 *
 * <table border="1">
 * <tr><th>Event Type</th><th>Extra Params</th></tr>
 * <tr><td>{@link EventType#property_set property_set}</td><td>A param named <tt>value</tt> that
 *      has the value of the property set.</td></tr>
 * <tr><td>{@link EventType#property_deleted property_deleted}</td><td><i>None</i></td></tr>
 * <tr><td>{@link EventType#xml_property_set xml_property_set}</td><td>A param named <tt>value</tt> that
 *      has the value of the property set.</td></tr>
 * <tr><td>{@link EventType#xml_property_deleted xml_property_deleted}</td><td><i>None</i></td></tr>
 * </table>
 *
 * @author Matt Tucker
 */
public class PropertyEventDispatcher {

    private static List<PropertyEventListener> listeners =
            new CopyOnWriteArrayList<PropertyEventListener>();

    private PropertyEventDispatcher() {
        // Not instantiable.
    }

    /**
     * Registers a listener to receive events.
     *
     * @param listener the listener.
     */
    public static void addListener(PropertyEventListener listener) {
        if (listener == null) {
            throw new NullPointerException();
        }
        listeners.add(listener);
    }

    /**
     * Unregisters a listener to receive events.
     *
     * @param listener the listener.
     */
    public static void removeListener(PropertyEventListener listener) {
        listeners.remove(listener);
    }

    /**
     * Dispatches an event to all listeners.
     *
     * @param property the property.
     * @param eventType the event type.
     * @param params event parameters.
     */
    public static void dispatchEvent(String property, EventType eventType, Map params) {
        for (PropertyEventListener listener : listeners) {
            try {
                switch (eventType) {
                    case property_set: {
                        listener.propertySet(property, params);
                        break;
                    }
                    case property_deleted: {
                        listener.propertyDeleted(property, params);
                        break;
                    }
                    case xml_property_set: {
                        listener.xmlPropertySet(property, params);
                        break;
                    }
                    case xml_property_deleted: {
                        listener.xmlPropertyDeleted(property, params);
                        break;
                    }
                    default:
                        break;
                }
            }
            catch (Exception e) {
                Log.error(e);
            }
        }
    }

    /**
     * Represents valid event types.
     */
    public enum EventType {

        /**
         * A property was set.
         */
        property_set,

        /**
         * A property was deleted.
         */
        property_deleted,

        /**
         * An XML property was set.
         */
        xml_property_set,

        /**
         * An XML property was deleted.
         */
        xml_property_deleted;
    }
}