Flex DataGrid 数据的上下移动、增加、删除操作

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" minWidth="955" minHeight="600">
    <mx:Script>
        <![CDATA[
            import mx.collections.ArrayCollection;
            import mx.collections.IList;
            [Bindable]
            private var arrayCollection:ArrayCollection=new ArrayCollection([
                {id:"1",name:"小1"},
                {id:"2",name:"小2"},
                {id:"3",name:"小3"}
            ]);

            public function moveUp():void{
                var i : int = dataGrid1.selectedIndex;
                if (i >= 1&&dataGrid1.selectedItem){
                    IList(dataGrid1.dataProvider).addItemAt(dataGrid1.selectedItem,i-1);
                    IList(dataGrid1.dataProvider).removeItemAt(i+1);
                    dataGrid1.selectedIndex = i;

                }
            }

            public function moveDown():void{
                var i : int = dataGrid1.selectedIndex;
                if (i < (ArrayCollection(dataGrid1.dataProvider).length - 1) && dataGrid1.selectedItem){
                    IList(dataGrid1.dataProvider).addItemAt(dataGrid1.selectedItem,i + 2);
                    IList(dataGrid1.dataProvider).removeItemAt(i);
                    dataGrid1.selectedIndex = i;
                }
            }

            private function addColumnItem():void{
                arrayCollection.addItem({id:"id",name:"name"});
                dataGrid1.selectedIndex=arrayCollection.length;
            }

            private function delColunmItem(colunmItem:Object):void{
                arrayCollection.removeItemAt(arrayCollection.getItemIndex(colunmItem));
                dataGrid1.selectedIndex=arrayCollection.length-1;
            }
        ]]>
    </mx:Script>
    <mx:Panel width="500" height="300" title="DataGrid简单测试">
        <mx:HBox width="100%" height="100%">
            <mx:DataGrid width="100%" height="100%" id="dataGrid1" dataProvider="{arrayCollection}">
                <mx:columns>
                    <mx:DataGridColumn dataField="id" headerText="ID"/>
                    <mx:DataGridColumn dataField="name" headerText="姓名"/>
                </mx:columns>
            </mx:DataGrid>
            <mx:VBox width="60">
                <mx:Spacer height="100%"/>
                <mx:Button label="上移" id="up" click="moveUp()" enabled="{dataGrid1.selectedItem?true:false}"/>
                <mx:Spacer height="5"/>
                <mx:Button label="下移" id="down" click="moveDown()" enabled="{dataGrid1.selectedItem?true:false}"/>
                <mx:Spacer height="5"/>
                <mx:Button label="╂" click="addColumnItem()"/>
                <mx:Spacer height="5"/>
                <mx:Button label="━" enabled="{dataGrid1.selectedItem?true:false}" click="delColunmItem(dataGrid1.selectedItem)"/>
                <mx:Spacer height="100%"/>
            </mx:VBox>
        </mx:HBox>
    </mx:Panel>
</mx:Application>

移动的代码参考地址：http://www.iteye.com/topic/192956