Actionscript 3.0 事件机制剖析--自定义事件实现

  Actionscript 3.0 事件机制剖析

                                               --自定义事件实现

    

     接着上一篇，用一个实例来说明如何自定义一个Actionscript 3的事件。在这个事件中实现了闹钟功能，当时间到的时候，发送一个TIME_ALARM事件，闹钟响应，并提示消息。代码实现如下：

 package {/** * Written by Leezhm, 21st February, 2009 * Contact : [e-mail] * Last Modified by Leezhm on 22nd February, 2009 **/import flash.display.Sprite;import flash.events.Event;import flash.events.TimerEvent;import flash.utils.Timer;public class TestEvent extends Sprite{private var _timerClock:Timer;public function TestEvent():void{if (stage){InitApplication();}else{this.addEventListener(Event.ADDED_TO_STAGE, InitApplication);}}private function InitApplication():void{this.removeEventListener(Event.ADDED_TO_STAGE, InitApplication);// Add a listener for the TIME_ALARM event.this.addEventListener(AlarmEvent.TIME_ALARM, OnAlarmClock);this._timerClock = new Timer(0, 1);this._timerClock.addEventListener(TimerEvent.TIMER, OnTimerClock);SetAlarmClock(11, 15);//测试时间为2009-02-23 11:15:00}/** * Dispatch the TIME_ALARM event when the currrent time was be * the alarm setting time */private function OnTimerClock(evt:TimerEvent):void{var _alarmEvent:AlarmEvent = new AlarmEvent();_alarmEvent.message = "Please get up!!!It's time for breakfast!!!";this.dispatchEvent(_alarmEvent);}/** * the event handling function of TIME_ALARM. */private function OnAlarmClock(evt:AlarmEvent):void{trace("Alarm!!!");var _alarmClone:Event = evt.clone();trace(_alarmClone);}/** * Sets the time at which the alarm should go off. * @param hour The hour portion of the alarm time. * @param minutes The minutes portion of the alarm time. */private function SetAlarmClock(hour:uint, minutes:uint):void{var _now:Date = new Date();var _alarmClock:Date = new Date(_now.fullYear, _now.month, _now.date, hour, minutes); if (_alarmClock <= _now){trace("Error time! Now is " + _now.toLocaleDateString());}else{//reset the timer;this._timerClock.reset();this._timerClock.delay = _alarmClock.time - _now.time;this._timerClock.start();}}}}

     AlarmEvent事件是继续了flash.events.Event事件，在此事件中添加了新的属性message，它是当闹钟时间到时的提示信息。在继承flash.events.Event事件的子类中必须override父类的clone方法，同样也应该继承toString方法。下面给出一张Adobe的官方文档Programming ActionScript 3.0中关于继承Event事件的说明图，如下：

 

 

  关于本例中AlarmEvent的实现如下：

 package {/** * Written by Leezhm, 21st February, 2009 * Contact : [e-mail] * Last Modified by Leezhm on 22nd February, 2009 **/import flash.events.Event;public class AlarmEvent extends Event{public static const TIME_ALARM:String = "timealarm";private var _messages:String = "";public function AlarmEvent():void{super(TIME_ALARM);}public function set message(msg:String):void{if ("" != msg){this._messages = msg;}}public function get message():String{return this._messages;}public override function clone():Event {var _tmpAlarm:AlarmEvent = new AlarmEvent();_tmpAlarm._messages = this._messages;return _tmpAlarm;}public override function toString():String {return this.formatToString("AlarmEvent", "type", "bubbles", "cancelable", "eventPhase", "message");}}}

 

fla文件可以自己建立，上面不需要添加任何元件，关联到TestEvent类即可，然后设置闹钟时间。运行结果截图如下：