Flex中用state来表示不同的状态的经典的例子

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"><mx:states><mx:State name="Register"><mx:AddChild relativeTo="{loginForm}" position="lastChild"><mx:target><mx:FormItem id="confirm" label="Confirm:"><mx:TextInput/></mx:FormItem></mx:target></mx:AddChild><mx:SetProperty target="{loginPanel}" name="title" value="Register"/><mx:SetProperty target="{loginButton}" name="label" value="Register"/><mx:SetStyle target="{loginButton}" name="color" value="blue"/><mx:RemoveChild target="{registerLink}"/><mx:AddChild relativeTo="{spacer1}" position="before"><mx:target><mx:LinkButton id="loginLink" label="Return to Login" click="currentState=''"/></mx:target></mx:AddChild></mx:State></mx:states><!-- Define a Panel container that defines the login form.--><mx:Panel title="Login" id="loginPanel"  horizontalScrollPolicy="off" verticalScrollPolicy="off"  paddingTop="10" paddingLeft="10" paddingRight="10" paddingBottom="10"><mx:Text width="100%" color="blue" text="Click the 'Need to Register?' link to change state. Click the 'Return to Login' link to return to the base state."/><mx:Form id="loginForm" ><mx:FormItem label="Username:"><mx:TextInput/></mx:FormItem><mx:FormItem label="Password:"><mx:TextInput displayAsPassword="true"/></mx:FormItem></mx:Form><mx:ControlBar><mx:LinkButton id="registerLink"   label="Need to Register?"   click="currentState='Register'"/><mx:Spacer width="100%" id="spacer1"/><mx:Button label="Login" id="loginButton"/></mx:ControlBar></mx:Panel></mx:Application>