flex中与XML相关的问题

<mx:Application xmlns:mx=\"http://www.adobe.com/2006/mxml\"
                width=\"100%\"
                height=\"100%\">

    <mx:Script>
    <![CDATA[
        private function labelBuilder(item:Object, column:DataGridColumn):String {
            var ref:Object = this.deriveComplexColumnData(item, column.dataField);
            var label:String = \"\";
            for (var r:String in ref) {
                label += ref[r] + \"; \";
            }
            return label;
        }

        private function deriveComplexColumnData(data:Object, dataField:String):Object {
            var currentRef:Object = data;
            var tokens:Array = dataField.split(\'.\');
            if (tokens.length > 0) {
                for (var i:int = 0; i < tokens.length; i++)
                    currentRef = currentRef[tokens[i]];
            }
            return currentRef;
        }
        ]]>
    </mx:Script>

    <mx:XML id=\"xml\">
        <node label=\"home\">
            <node label=\"1.0\">
                <node label=\"1.1\">
                    <node label=\"1.1.1\">
                        <node label=\"1.1.1.1\"/>
                        <node label=\"1.1.1.2\"/>
                    </node>
                    <node label=\"1.1.2\"/>
                    <node label=\"1.1.3\"/>
                </node>
                <node label=\"1.2\"/>
                <node label=\"1.3\">
                    <node label=\"1.3.1\"/>
                    <node label=\"1.3.2\"/>
                </node>
            </node>
            <node label=\"2.0\"/>
        </node>
    </mx:XML>

    <mx:DataGrid id=\"dg\" width=\"100%\" height=\"100%\" dataProvider=\"{xml.node}\">
        <mx:columns>
            <mx:DataGridColumn dataField=\"@label\" headerText=\"Node1\"/>
            <mx:DataGridColumn dataField=\"node.@label\" headerText=\"Node2\"/>
            <mx:DataGridColumn dataField=\"node.node.@label\" headerText=\"Node3\"/>
            <mx:DataGridColumn dataField=\"node.node.node.@label\" labelFunction=\"{ labelBuilder }\" headerText=\"Node4\"/>
        </mx:columns>
    </mx:DataGrid>

</mx:Application>

DataGridColum

labelBuilder

<mx:Script>
    <![CDATA[

        // Event handler to format the input.            
        private function Format():void
        {
            // The format() method returns the formatted String,
            // or an empty String if there is an error.
            var formattedVal:String = numberFormatter.format(inputVal.text);

            if (formattedVal.length==0) {
                // If there is an error, the Format.error property 
                // contains the reason.
                formattedNumber.text=numberFormatter.error;
            }

            else {
                formattedNumber.text=formattedVal;
            }
        }
    ]]>
</mx:Script>

<mx:NumberFormatter id=\"numberFormatter\"/>

<mx:Panel title=\"NumberFormatter Example\" width=\"75%\" height=\"75%\" 
        paddingTop=\"10\" paddingLeft=\"10\" paddingRight=\"10\" paddingBottom=\"10\">

    <mx:Form>
        <mx:FormItem label=\"Enter number - a letter is invalid:\">
            <mx:TextInput id=\"inputVal\" text=\"\" width=\"75%\"/>
        </mx:FormItem>

        <mx:FormItem label=\"Formatted number: \">
            <mx:TextInput id=\"formattedNumber\" editable=\"false\" width=\"75%\"/>
        </mx:FormItem>

        <mx:FormItem>
            <mx:Button label=\"Validate and Format\" click=\"Format();\"/>
        </mx:FormItem>
    </mx:Form>

</mx:Panel>

public static function getNestLevel(node:XML):int {
    var level:int = 0;
    while (node.parent()) {
        level++;
        node = node.parent();
    }
    return level;
}