Flex Tree节点的展开与收缩

<?xml version="1.0" encoding="utf-8"?>
<!--展开或关闭tree的节点， -->
<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">
	<fx:Script>
		<![CDATA[
			protected function XMLTree_renderHandler (event:Event):void
			{
				this.XMLTree.expandItem(XML(this.treeData.node), true, true);
			}
			
			//展开所有节点
			protected function button1_clickHandler (event:MouseEvent):void
			{
				collapseHandler();
				this.XMLTree.openItems = this.treeData..node;
			}
				
			//展开树的第一层
			protected function button2_clickHandler (event:MouseEvent):void
			{
				collapseHandler();
				this.XMLTree.expandItem(XML(this.treeData.node), true, true);
			}
			
			//展开名为child5的节点
			protected function button3_clickHandler (event:MouseEvent):void
			{
				collapseHandler();
				//方法一
				this.XMLTree.openItems = [XML(this.treeData.node), XML(this.treeData..
					node.(@label == 'Child 5'))];
				//方法二 
				//                if (!XMLTree.isItemOpen(XML(this.treeData.node)))
				//                {
				//                    this.XMLTree.expandItem(XML(this.treeData.node), true, true);
				//                }
				//                this.XMLTree.expandItem(XML(this.treeData..node.(@label == 'Child 5')),
				//                    true, true);
			}
			
			//收起全部节点
			protected function collapseHandler ():void
			{
				this.XMLTree.openItems = [];
			}
		]]>
	</fx:Script>
	<fx:Declarations>
		<fx:XMLList id="treeData">
			<root>
				<node label="Parent 1">
					<node label="Child 1"/>
					<node label="Child 2">
						<node label="Grandchild 1"/>
						<node label="Grandchild 2"/>
					</node>
					<node label="Child 3"/>
					<node label="Child 4"/>
					<node label="Child 5">
						<node label="Grandchild 1"/>
						<node label="Grandchild 2"/>
					</node>
				</node>
			</root>
		</fx:XMLList>
	</fx:Declarations>
	<s:layout>
		<s:VerticalLayout horizontalAlign="center" verticalAlign="middle"/>
	</s:layout>
	<s:VGroup width="400" horizontalAlign="center">
		<mx:Tree id="XMLTree" width="100%" height="270" showRoot="false" labelField="@label" dataProvider="{this.treeData}" borderVisible="false"/>
		<s:HGroup>
			<s:Button label="展开所有节点" click="button1_clickHandler(event)"/>
			<s:Button label="展开第一层" click="button2_clickHandler(event)"/>
			<s:Button label="展开 名为Child5的节点" click="button3_clickHandler(event)"/>
			<s:Button label="收缩树" click="collapseHandler()"/>
		</s:HGroup>
	</s:VGroup>
</s:Application>