1/**
2 * Copyright 2003-2007 Jive Software.
3 *
4 * All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package org.jivesoftware.smackx.workgroup.util;
18
19import java.lang.reflect.Method;
20import java.util.ArrayList;
21import java.util.ListIterator;
22
23/**
24 * This class is a very flexible event dispatcher which implements Runnable so that it can
25 * dispatch easily from a newly created thread. The usage of this in code is more or less:
26 * create a new instance of this class, use addListenerTriplet to add as many listeners
27 * as desired to be messaged, create a new Thread using the instance of this class created
28 * as the argument to the constructor, start the new Thread instance.<p>
29 *
30 * Also, this is intended to be used to message methods that either return void, or have
31 * a return which the developer using this class is uninterested in receiving.
32 *
33 * @author loki der quaeler
34 */
35public class ListenerEventDispatcher
36    implements Runnable {
37
38    protected transient ArrayList<TripletContainer> triplets;
39
40    protected transient boolean hasFinishedDispatching;
41    protected transient boolean isRunning;
42
43    public ListenerEventDispatcher () {
44        super();
45
46        this.triplets = new ArrayList<TripletContainer>();
47
48        this.hasFinishedDispatching = false;
49        this.isRunning = false;
50    }
51
52    /**
53     * Add a listener triplet - the instance of the listener to be messaged, the Method on which
54     *  the listener should be messaged, and the Object array of arguments to be supplied to the
55     *  Method. No attempts are made to determine whether this triplet was already added.<br>
56     *
57     * Messages are dispatched in the order in which they're added via this method; so if triplet
58     *  X is added after triplet Z, then triplet Z will undergo messaging prior to triplet X.<br>
59     *
60     * This method should not be called once the owning Thread instance has been started; if it
61     *  is called, the triplet will not be added to the messaging queue.<br>
62     *
63     * @param listenerInstance the instance of the listener to receive the associated notification
64     * @param listenerMethod the Method instance representing the method through which notification
65     *                          will occur
66     * @param methodArguments the arguments supplied to the notification method
67     */
68    public void addListenerTriplet(Object listenerInstance, Method listenerMethod,
69            Object[] methodArguments)
70    {
71        if (!this.isRunning) {
72            this.triplets.add(new TripletContainer(listenerInstance, listenerMethod,
73                    methodArguments));
74        }
75    }
76
77    /**
78     * @return whether this instance has finished dispatching its messages
79     */
80    public boolean hasFinished() {
81        return this.hasFinishedDispatching;
82    }
83
84    public void run() {
85        ListIterator<TripletContainer> li = null;
86
87        this.isRunning = true;
88
89        li = this.triplets.listIterator();
90        while (li.hasNext()) {
91            TripletContainer tc = li.next();
92
93            try {
94                tc.getListenerMethod().invoke(tc.getListenerInstance(), tc.getMethodArguments());
95            } catch (Exception e) {
96                System.err.println("Exception dispatching an event: " + e);
97
98                e.printStackTrace();
99            }
100        }
101
102        this.hasFinishedDispatching = true;
103    }
104
105
106    protected class TripletContainer {
107
108        protected Object listenerInstance;
109        protected Method listenerMethod;
110        protected Object[] methodArguments;
111
112        protected TripletContainer (Object inst, Method meth, Object[] args) {
113            super();
114
115            this.listenerInstance = inst;
116            this.listenerMethod = meth;
117            this.methodArguments = args;
118        }
119
120        protected Object getListenerInstance() {
121            return this.listenerInstance;
122        }
123
124        protected Method getListenerMethod() {
125            return this.listenerMethod;
126        }
127
128        protected Object[] getMethodArguments() {
129            return this.methodArguments;
130        }
131    }
132}