001/** 002 * 003 * Copyright 2003-2007 Jive Software. 004 * 005 * Licensed under the Apache License, Version 2.0 (the "License"); 006 * you may not use this file except in compliance with the License. 007 * You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.jivesoftware.smackx.workgroup.util; 018 019import java.lang.reflect.Method; 020import java.util.ArrayList; 021import java.util.ListIterator; 022import java.util.logging.Level; 023import java.util.logging.Logger; 024 025/** 026 * This class is a very flexible event dispatcher which implements Runnable so that it can 027 * dispatch easily from a newly created thread. The usage of this in code is more or less: 028 * create a new instance of this class, use addListenerTriplet to add as many listeners 029 * as desired to be messaged, create a new Thread using the instance of this class created 030 * as the argument to the constructor, start the new Thread instance.<p> 031 * 032 * Also, this is intended to be used to message methods that either return void, or have 033 * a return which the developer using this class is uninterested in receiving. 034 * 035 * @author loki der quaeler 036 */ 037public class ListenerEventDispatcher implements Runnable { 038 private static final Logger LOGGER = Logger.getLogger(ListenerEventDispatcher.class.getName()); 039 040 protected transient ArrayList<TripletContainer> triplets; 041 042 protected transient boolean hasFinishedDispatching; 043 protected transient boolean isRunning; 044 045 public ListenerEventDispatcher () { 046 super(); 047 048 this.triplets = new ArrayList<TripletContainer>(); 049 050 this.hasFinishedDispatching = false; 051 this.isRunning = false; 052 } 053 054 /** 055 * Add a listener triplet - the instance of the listener to be messaged, the Method on which 056 * the listener should be messaged, and the Object array of arguments to be supplied to the 057 * Method. No attempts are made to determine whether this triplet was already added.<br> 058 * 059 * Messages are dispatched in the order in which they're added via this method; so if triplet 060 * X is added after triplet Z, then triplet Z will undergo messaging prior to triplet X.<br> 061 * 062 * This method should not be called once the owning Thread instance has been started; if it 063 * is called, the triplet will not be added to the messaging queue.<br> 064 * 065 * @param listenerInstance the instance of the listener to receive the associated notification 066 * @param listenerMethod the Method instance representing the method through which notification 067 * will occur 068 * @param methodArguments the arguments supplied to the notification method 069 */ 070 public void addListenerTriplet(Object listenerInstance, Method listenerMethod, 071 Object[] methodArguments) 072 { 073 if (!this.isRunning) { 074 this.triplets.add(new TripletContainer(listenerInstance, listenerMethod, 075 methodArguments)); 076 } 077 } 078 079 /** 080 * @return whether this instance has finished dispatching its messages 081 */ 082 public boolean hasFinished() { 083 return this.hasFinishedDispatching; 084 } 085 086 public void run() { 087 ListIterator<TripletContainer> li = null; 088 089 this.isRunning = true; 090 091 li = this.triplets.listIterator(); 092 while (li.hasNext()) { 093 TripletContainer tc = li.next(); 094 095 try { 096 tc.getListenerMethod().invoke(tc.getListenerInstance(), tc.getMethodArguments()); 097 } catch (Exception e) { 098 LOGGER.log(Level.SEVERE, "Exception dispatching an event", e); 099 } 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}