文章关键字：|flex|树形|下拉框|treecombobox|

不多说了，组件代码如下：

<?xml version="1.0" encoding="utf-8"?>
<mx:ComboBox  xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="initComponent()">
<mx:Script>
    <![CDATA[
           import mx.events.FlexEvent;
           [Bindable]
           private var _label:String;
           [Bindable]
           public var treeSelectedItem:Object;

           public function initComponent():void
           {
           
           }
                       
           public function updateLabel(event:*):void{ 
                    _label = event.currentTarget.selectedItem[this.labelField];    
                    treeSelectedItem = event.currentTarget.selectedItem;
           }
          
           override protected function updateDisplayList(unscaledWidth:Number,
                                                  unscaledHeight:Number):void
            {
                super.updateDisplayList(unscaledWidth, unscaledHeight); 
               
                if(dropdown && _label != null){  
                    text = _label;
                }
            }

            
    ]]>
</mx:Script>
    <mx:dropdownFactory>
      <mx:Component>
        <mx:Tree creationComplete="initTree()" change="outerDocument.updateLabel(event)" showRoot="true" height="500" width="500">
         <mx:Script>
                <![CDATA[
                public function initTree():void {
                    var len:int=super.dataProvider.length;
                    for(var i:int;i<len;i++)
                    {
                        super.expandChildrenOf(super.dataProvider[i], true);
                    }
                    super.selectedItem=outerDocument.treeSelectedItem;
                }
                ]]>
            </mx:Script>
        </mx:Tree>
     </mx:Component>
    </mx:dropdownFactory>
</mx:ComboBox>

调用的app代码如下：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" xmlns:ns1="components.*">
    <ns1:ComboTree  width="300" id="combo" labelField="@label" >
        <mx:XMLListCollection id="MailBox">
            <mx:XMLList>
                <folder label="Mail">
                 <folder label="INBOX"/>
                 <folder label="Personal Folder">
                    <Pfolder label="Business" />
                     <Pfolder label="Demo" />
                         <Pfolder label="Personal" isBranch="true" />
                         <Pfolder label="Saved Mail" />
                    </folder>
                    <folder label="Sent" />
                    <folder label="Trash" />
                </folder>
                <folder label="Mail2">
                 <folder label="INBOX2"/>
                 <folder label="Personal Folder2">
                    <Pfolder label="Business2" />
                     <Pfolder label="Demo2" />
                         <Pfolder label="Personal2" isBranch="true" />
                         <Pfolder label="Saved Mail2" />
                    </folder>
                    <folder label="Sent2" />
                    <folder label="Trash2" />
                </folder>
            </mx:XMLList>
        </mx:XMLListCollection>
    </ns1:ComboTree>
</mx:Application>