flex4的viewstack之間的跳轉

我的文件目錄結構

我的chatroom.mxml

<?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="955" minHeight="600"
			   xmlns:hearain="hearain.*">
	<fx:Declarations>
		<!-- 將非可視元素（例如服務、值對象）放在此處 -->
	</fx:Declarations>
	<fx:Script>
		<![CDATA[

		]]>
	</fx:Script>
	<mx:ViewStack id="room">
		<s:NavigatorContent>
			<hearain:login id="login">
			</hearain:login>	
		</s:NavigatorContent>
		<s:NavigatorContent>
			<hearain:welcome id="welcome" width="300" height="200">
			</hearain:welcome>
		</s:NavigatorContent>
	</mx:ViewStack>
</s:Application>

我的login.mxml組件

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
		 xmlns:s="library://ns.adobe.com/flex/spark"
		 creationComplete="group1_creationCompleteHandler(event)"
		 xmlns:mx="library://ns.adobe.com/flex/mx" width="400" height="300">
	<s:layout>
		<s:VerticalLayout/>
	</s:layout>
	<fx:Script>
		<![CDATA[
			import mx.containers.ViewStack;
			import mx.core.FlexGlobals;
			import mx.events.FlexEvent;
			private var vs:ViewStack; 　　　　//vs是main.mxml中定義的viewstack
			
			protected function group1_creationCompleteHandler(event:FlexEvent):void
			{
				// TODO Auto-generated method stub
				if(FlexGlobals.topLevelApplication is chatroom){
					if(FlexGlobals.topLevelApplication.room is ViewStack){
						vs = FlexGlobals.topLevelApplication.room as ViewStack;
					}
				}
			}
//			private function getChild(str:String):Object  //這段代碼是爲了獲得指定頁面對應的對象
//			{
//				for each(var obj:Object in vs.getChildren())  //遍歷vs中的所有子組件(即所有頁面)，頁面不會太多，頂多一二十個，所以這個方法不會太耗時
//				{
//					if(obj.name === str) //如果是想找的頁面，就返回這個對象。比如想找到welcome.mxml，則令str="welcome"
//					{
//						break;
//					}
//				}
//				return obj;
//			}
			
			protected function button1_clickHandler(event:MouseEvent):void
			{
				// TODO Auto-generated method stub
				vs.selectedIndex = 1;//跳轉至welcomeu頁面
			}
			
		]]>
	</fx:Script>
	<fx:Declarations>
		<!-- 將非可視元素（例如服務、值對象）放在此處 -->
	</fx:Declarations>
	<s:Button x="200" y="121" label="登錄" click="button1_clickHandler(event)" />
</s:Group>

我的welcome.mxml組件

<?xml version="1.0" encoding="utf-8"?>
<s:Group xmlns:fx="http://ns.adobe.com/mxml/2009" 
		 xmlns:s="library://ns.adobe.com/flex/spark" 
		 xmlns:mx="library://ns.adobe.com/flex/mx" width="400" height="300">
	<s:layout>
		<s:VerticalLayout/>
	</s:layout>
	<fx:Declarations>
		<!-- 將非可視元素（例如服務、值對象）放在此處 -->
	</fx:Declarations>
	<s:Label id="w" text="歡迎窗口" />
</s:Group>

我的運行結果：

點擊登陸後跳轉至welcome頁面