<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical"> <mx:Script> <![CDATA[ private function expandTree(expand:Boolean):void { tree.validateNow(); tree.expandChildrenOf(treeData, expand); } ]]> </mx:Script> <mx:XML id="treeData" xmlns=""> <root label="root"> <menu label="node1"> <menu label="node1.1"/> <menu label="node1.2"/> <menu label="node1.3"/> </menu> <menu label="node2"> <menu label="node2.1"/> <menu label="node2.2"/> <menu label="node2.3"/> </menu> </root> </mx:XML> <mx:Tree id="tree" dataProvider="{treeData}" width="200" height="300" labelField="@label"/> <mx:Button label="全部展开" click="expandTree(true)"/> <mx:Button label="全部收起" click="expandTree(false)"/></mx:Application>