绑定自定义属性——[bindable]和事件

<? 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 " >
     < fx:Declarations >
         <!--  将非可视元素（例如服务、值对象）放在此处  -->
     </ fx:Declarations >
     < fx:Script >
         <! [CDATA[
            
             // 绑定属性
            [Bindable]
             private  var _product:String;
            
             // 在set方法中创建属性更新事件，并触发该事件，以通知Flex属性被更新
             public  function set product(value:String): void
            {
                _product  =  value;
                dispatchEvent( new  Event( " productChanged " ));
            }
            
             // 在get方法声明前，加入[Binndable]元素定义属性绑定。这样，当触发属性更新事件是，
             // Flex将会修改对应的属性
            
             // 没弄明白这个绑定事件在什么情况下能用到.
            [Bindable(event = " productChanged " )]
             public  function get product():String
            {
                 return  _product;
            }

        ]] >
     </ fx:Script >
</ s:Application >