FLEX实践—模拟Application与Module间的事件监听

一直找到如何在Application中发出一个事件，让Module捕获该事件并做出相应的动作。但是一直没找到，于是模拟了一个这样的情景。

WatchTest.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
<![CDATA[
import mx.binding.utils.ChangeWatcher;
import mx.controls.Alert;

//设置一个绑定变量，模拟Application的事件
[Bindable]public var monitor:String="AA";
private function changeMonitor():void{
monitor="BB";
}
]]>
</mx:Script>
<mx:Label x="419" y="97" text="{this.monitor}" width="157" height="23" id="watchTest"/>
<mx:Button x="603" y="95" label="Click me" click="changeMonitor()"/>
<mx:ModuleLoader x="286" y="160" width="596" height="315" url="Module/WatchModule.swf">
</mx:ModuleLoader>
</mx:Application>

WatchModule.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Module xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="400"
height="300" backgroundColor="#FBDADA" creationComplete="init()">
<mx:Script>
<![CDATA[
import mx.binding.utils.ChangeWatcher;
import mx.controls.Alert;
var watcher:ChangeWatcher;

private function init():void{

//设置一个观察器观察monitorText的值，一旦变化，立即触发valueChanged方法
watcher=ChangeWatcher.watch(monitorText,"text",valueChanged);
}
private function valueChanged(event:Event):void{
Alert.show("Application's monitor has changed!");
}
]]>
</mx:Script>

<!--绑定Application的monitor变量，注意使用parentApplication.monitor获取值-->
<mx:Label x="120" y="62" text="{this.parentApplication.monitor}" width="135" height="22" id="monitorText"/>

</mx:Module>