Flex 兑现图片的切换

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"	initialize="init()">
	<mx:Script>
	<![CDATA[
		import mx.controls.Alert;
		import mx.collections.ArrayCollection;
			
		[Bindable]
		private var _arrayCollection:ArrayCollection = 
                           new  ArrayCollection(["../img/images3.jpg",
				                            "../img/460.jpg",
				                            "../img/imagesCAV1ZQPW.jpg",
				                             "../img/images52.jpg",
				                             "../img/64d92fc7jw1dj9wsnjlmij.jpg",
				                             "../img/http_imgload.jpg",
				                             "../img/imagesCAA9E8GD.jpg",
				                             "../img/imagesCATSNEV1.jpg",
				                             "../img/imagesCAUFLAPQ.jpg"
			]);
            private var tim:Timer = new Timer(3000);
            
            private var j:int = 0;
			
	    private function init():void{
			 if(_arrayCollection.length != 0){
				 showImage.source = _arrayCollection.getItemAt(0);
				 everySecondCheckImage();
			 }
	    }
		
	   private function clickImage(e:Event):void{
			 tim.stop();
			 showImage.source = e.currentTarget.getRepeaterItem();
			 j = getImageIndexOf(e.currentTarget.getRepeaterItem());
			 hboxLength.horizontalScrollPosition = 120 * j;
			 tim.start();
	   }
			
            //每三秒切换一次
            private function everySecondCheckImage():void{
            	tim.addEventListener(TimerEvent.TIMER,function(e:TimerEvent):void{
            		j = j + 1;
            		hboxLength.horizontalScrollPosition = 120 * j;
            		if(j > _arrayCollection.length - 1){
            			j = 0;
            			hboxLength.horizontalScrollPosition = 0;
            		}
            		showImage.source = _arrayCollection.getItemAt(j);
            	});
            	tim.start();
            }
            
              //返回当前图片的索引
              private function getImageIndexOf(obj:Object):int{
            	  return _arrayCollection.getItemIndex(obj);
              }
			
		]]>
	</mx:Script>
	
	
	<mx:VBox x="270" y="10" width="611" 
                  borderStyle="solid" borderThickness="1" height="530">
		<mx:VBox borderStyle="solid" borderThickness="1" 
                      paddingTop="2" paddingRight="2" paddingBottom="2"
                      paddingLeft="2" width="607" height="397">
			<mx:Image id="showImage" width="600"
                                  height="391" x="211" y="173" 
                                  maintainAspectRatio="false"/>
		</mx:VBox>
		
		<mx:HBox width="606" height="125" id="hboxLength">
			<mx:Repeater dataProvider="{_arrayCollection}" id="repArray">
				<mx:VBox buttonMode="true" 
                                      borderThickness="1" borderStyle="solid" 
                                      paddingTop="2" paddingRight="2" 
                                      paddingBottom="2" paddingLeft="2">
			<mx:Image source="{repArray.currentItem}"          
                                     width="109" height="100" 
                                      maintainAspectRatio="false" click="clickImage(event)"/>
				</mx:VBox>
			</mx:Repeater>	
		</mx:HBox>
	</mx:VBox>
</mx:Application>