Flex中监听变量是否发生改变的方法

方式一：使用ObjectProxy

 
 

<?xml?version="1.0"?encoding="utf-8"?>?
  
  
<mx:Application?xmlns:mx="http://www.adobe.com/2006/mxml"?layout="absolute"?minWidth="955"?minHeight="600"?
  
  
?????????????????creationComplete="init()">?
  
  
????<mx:Script>?
  
  
????????<![CDATA[?
  
  
????????????import?mx.controls.Alert;?
  
  
????????????import?mx.events.FlexEvent;?
  
  
????????????import?mx.events.PropertyChangeEvent;?
  
  
????????????import?mx.utils.ObjectProxy;?
  
  
?????????????
  
  
????????????private?var?objectProxy:ObjectProxy=new?ObjectProxy();?
  
  
????????????protected?function?init():void?
  
  
????????????{?
  
  
????????????????objectProxy.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE,?changeMethod);??
  
  
????????????}?
  
  
?????????????
  
  
????????????private?function?changeMethod(evt:PropertyChangeEvent):void?{?
  
  
????????????????if(evt.newValue){?//值有改变?
  
  
??????????????????trace("变化的属性名称："+evt.property.toString()+"；发生更改的对象(在监听对象的时候特别有用)："+evt.source+"|旧值："+evt.oldValue+"|新值："+evt.newValue);?
  
  
????????????????}?
  
  
????????????}??
  
  
?????????????
  
  
????????????public?function?buttonClick():void{?
  
  
????????????????objectProxy.name=new?Date().getTime();?
  
  
????????????}?
  
  
?????????????
  
  
????????]]>?
  
  
????</mx:Script>?
  
  
????<mx:Button?label="点击更改变量的值"?click="buttonClick()"/>?
  
  
</mx:Application>?
 
 

变化的属性名称：name；发生更改的对象(在监听对象的时候特别有用)：[object Object]|旧值：null|新值：1363690634734
变化的属性名称：name；发生更改的对象(在监听对象的时候特别有用)：[object Object]|旧值：1363690634734|新值：1363690638142
变化的属性名称：name；发生更改的对象(在监听对象的时候特别有用)：[object Object]|旧值：1363690638142|新值：1363690648282
变化的属性名称：name；发生更改的对象(在监听对象的时候特别有用)：[object Object]|旧值：1363690648282|新值：1363690650001
变化的属性名称：name；发生更改的对象(在监听对象的时候特别有用)：[object Object]|旧值：1363690650001|新值：1363690652340

官方地址：http://livedocs.adobe.com/flex/3_cn/mx/events/PropertyChangeEvent.html

方式二：使用BindingUtils 

 
 

<?xml?version="1.0"?encoding="utf-8"?>?
  
  
<mx:Application?xmlns:mx="http://www.adobe.com/2006/mxml"?layout="absolute"?minWidth="955"?minHeight="600"?
  
  
?????????????????creationComplete="init()">?
  
  
????<mx:Script>?
  
  
????????<![CDATA[?
  
  
????????????import?mx.binding.utils.BindingUtils;?
  
  
????????????import?mx.controls.Alert;?
  
  
????????????import?mx.events.FlexEvent;?
  
  
????????????import?mx.events.PropertyChangeEvent;?
  
  
????????????import?mx.utils.ObjectProxy;?
  
  
?????????????
  
  
????????????[Bindable]?//必须的，不然检测不到变化?
  
  
????????????public?var?object:String="123";?
  
  
????????????protected?function?init():void?
  
  
????????????{?
  
  
????????????????BindingUtils.bindSetter(changeMethod,this,'object');?
  
  
????????????}?
  
  
?????????????
  
  
????????????private?function?changeMethod(str:String):void?{?
  
  
????????????????trace("changeMethod有变化,变化后的值为："+str);?
  
  
????????????}??
  
  
?????????????
  
  
????????????public?function?buttonClick():void{?
  
  
????????????????object=new?Date().getTime()+"";?
  
  
????????????????trace("当前时间字符串："+object);?
  
  
????????????}?
  
  
?????????????
  
  
????????????/*?日志输出?
  
  
????????????changeMethod有变化,变化后的值为：123?
  
  
????????????changeMethod有变化,变化后的值为：1364007051727?
  
  
????????????当前时间字符串：1364007051727?
  
  
????????????changeMethod有变化,变化后的值为：1364007052587?
  
  
????????????当前时间字符串：1364007052587??
  
  
????????????*/?
  
  
?????????????
  
  
????????]]>?
  
  
????</mx:Script>?
  
  
????<mx:Button?label="点击更改变量的值"?click="buttonClick()"/>?
  
  
</mx:Application>?
 
 

官方地址：http://livedocs.adobe.com/flex/3_cn/langref/mx/binding/utils/BindingUtils.html