与状态有关的事件

enterState:进入一个新状态后触发，触发者是state object和组件。
exitState:一个状态将要离开时触发，触发者是state object和组件。
currentStateChanging：在状态即将改变时触发。它被一个currentState属性值改变的组件触发。你可以利用这个事件向服务器请求即将被新状态用到的数据。
currentStateChange：在一个状态已经完全改变了后触发。你可以利用这个事件向服务器发回一个数据，指明用户当前的状态。

<?xml version="1.0"?>
<!-- states\StatesSimpleEvent.mxml -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:mx="library://ns.adobe.com/flex/halo"
xmlns:s="library://ns.adobe.com/flex/spark">
<s:states>
<!-- Define the new view states. -->
<s:State name="default"
enterState="MyEnterTA.text = 'Enter state: default';"
exitState="MyExitTA.text = 'Exit state: default';"/>
<s:State name="NewButton"
enterState="MyEnterTA.text = 'Enter state: NewButton';"
exitState="MyExitTA.text = 'Exit state: NewButton';"/>
</s:states>
<s:VGroup id="g1">
<s:HGroup>
<s:Button id="b1" label="Click Me"
enabled.NewButton="false"/>
<s:Button id="b2" label="New Button"
includeIn="NewButton"/>
</s:HGroup>
<s:Button label="Change to NewButton state"
click="currentState='NewButton';"/>
<s:Button label="Change to default view state"
click="currentState='default';"/>
<s:TextArea id="MyEnterTA"/>
<s:TextArea id="MyExitTA"/>
</s:VGroup>
</s:Application>