flex动态加载module

<?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"    xmlns:s="library://ns.adobe.com/flex/spark"    xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="400" minHeight="300" applicationComplete="application1_applicationCompleteHandler(event)"> <s:layout> <s:BasicLayout/> </s:layout> <fx:Script> <![CDATA[ import mx.core.IVisualElement; import mx.events.FlexEvent; import mx.events.ModuleEvent; import mx.modules.IModuleInfo; import mx.modules.ModuleManager; private var module:IModuleInfo; private var first:Boolean=true;//是否首次加载的判断标志 private var moduleInstance:Object;//用于保存加载后的实例引用 protected function button1_clickHandler(event:MouseEvent):void {    //非首次加载（先卸载） if (!first) { module.unload(); pnl.removeElement(moduleInstance as IVisualElement); } initModule(); module.load();   btn1.enabled = false; } private function onModuleReady(e:ModuleEvent):void {                moduleInstance  = e.module.factory.create();//注：这里千万不能用as做任何的转型，否则就报null object reference错误，原因不明                 this.pnl.addElement(moduleInstance as IVisualElement); //由于只能以Object方式操作，所以下面的代码，没办法智提示，只以盲打 moduleInstance.txtModule.text = Math.random().toString(); moduleInstance.x = moduleInstance.y = 10; trace(moduleInstance.Test()); first = false; btn1.enabled = true; } private function initModule():void { module = ModuleManager.getModule("module/MyModule.swf"); module.addEventListener(ModuleEvent.READY,onModuleReady);    } //应用加载完成时，就预先将Module初始化（甚至这时就可以load，只是不显示而已，以改善用户体验） protected function application1_applicationCompleteHandler(event:FlexEvent):void { initModule(); } ]]></fx:Script>   <s:Panel id="pnl" title="动态加载Module" left="10" top="10" bottom="50" right="10"></s:Panel> <s:Button click="button1_clickHandler(event)" label="load" horizontalCenter="0" bottom="10" id="btn1"> </s:Button> </s:Application>