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2008-06-24 16:21:00


数据分页功能在WEB应用非常广泛,虽然Flex基于Win的显示方式似乎没有必要,但实现应用中还是非常有用的。由于Flex的数据往往由其网络服务提供(如:WebService等),大量的数据传输和表现会影响Flex的性能;这个时候就可能通过数据分页的方法来获取当前显示数据,即能降低网络传的负担同时也能减少Flex的处理工作。

       首先分页控件需要的功能有:首页,上一页,下一页,未页和页数跳转等。

控件表现如下:



控件使用用例图

定义分页控件的事件:PageChange

相关事件参数对象:

 

package
{
    import flash.events.Event;
    import mx.events.IndexChangedEvent;
    
    public class PageChangeEvent extends flash.events.Event
    {
        public function PageChangeEvent(pageindex:int,pagesize:int)
        {
            super("PageChange");
            PageIndex= pageindex;
            PageSize =pagesize;
        }
        public var PageIndex:int=0;
        public var PageSize:int=0;
        public function Filter(list:Array):Array
        {
            var newlist:Array = new Array();
            var start:int = PageSize*PageIndex;
            var end:int = start+PageSize;
            for(var i:int = start;i<end;i++)
            {
                if(i< list.length)
                {
                    newlist.push(list[i]);
                }
                else
                    break;
            }
            return newlist;
        }
    }
}

下面是具体分页控件的代码:

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas xmlns:mx="" width="466" height="40">
<mx:Metadata>

    [Event(name="PageChange", type="PageChangeEvent",bubbles="true",cancelable="true")]

</mx:Metadata>

    <mx:Button click="method_le()" id="c_le" enabled="false" x="10" y="10" fontFamily="Georgia" width="44" height="24" minWidth="24" minHeight="24" label="<<">

    </mx:Button>
    <mx:Button click="method_l()" id="c_l" enabled="false" x="62" y="10" fontFamily="Georgia" width="44" height="24" minWidth="24" minHeight="24" label="<">
    
    </mx:Button>
    <mx:ComboBox rowCount="10" change="method_select()" id="c_select" enabled="false" x="114" y="10" width="54"></mx:ComboBox>
    <mx:Button click="method_r()" id="c_r" enabled="false" x="176" y="10" fontFamily="Georgia" width="44" height="24" minWidth="24" minHeight="24" label=">">
    
    </mx:Button>
    <mx:Button click="method_re()" label=">>" id="c_re" enabled="false" x="228" y="10" fontFamily="Georgia" width="44" height="24" minWidth="24" minHeight="24">

    </mx:Button>
    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;
            private var mRecordCount:int=0;
            private var mPageSize:int =8;//指定每页显示条数
            private var mPageIndex:int =0;
            private var mPageCount:int = 0;
            
            public function method_l():void
            {
                mPageIndex=mPageIndex-1;
                SetState();
                OnPageChange();
            }
            public function method_le():void
            {
                mPageIndex =0;
                SetState();
                OnPageChange();
            }
            public function method_r():void
            {
                mPageIndex=mPageIndex+1;
                SetState();
                OnPageChange();
            }
            public function method_re():void
            {
                mPageIndex=mPageCount-1;
                SetState();
                OnPageChange();
            }
            public function method_select():void
            {
                mPageIndex = c_select.selectedItem.data;
                SetState();
                OnPageChange();
            }
            public function get PageIndex():int
            {
                return mPageIndex;
            }
            
            
            //设置记录总数
            public function set RecordCount(count:int):void
            {
                mRecordCount= count;
                if(count >0)
                {
                    SetState();
                }
            }
            private function SetState():void
            {
                if(mRecordCount%mPageSize > 0)
                {
                    mPageCount = mRecordCount/mPageSize+1;
                }
                else
                {
                    mPageCount = mRecordCount/mPageSize;
                }
                var pages:Array = new Array();
                for(var i:int =1;i<=mPageCount;i++)
                {
                    pages.push( {label:i.toString(), data:i-1});
                }
                
                c_select.dataProvider= pages;
                c_select.selectedIndex= mPageIndex;
                if(mPageCount>1)
                {
                    c_select.enabled=true;
                    c_l.enabled=true;
                    c_le.enabled=true;
                    c_r.enabled=true;
                    c_re.enabled=true;
                    if(mPageIndex==0)
                    {
                        c_l.enabled=false;
                        c_le.enabled=false;
                    }
                    if(mPageIndex == mPageCount-1)
                    {
                        c_r.enabled=false;
                        c_re.enabled=false;
                    }
                }
                else
                {
                    c_select.enabled=false;
                    c_l.enabled=false;
                    c_le.enabled=false;
                    c_r.enabled=false;
                    c_re.enabled=false;
                }
                pageinfo.text="Records:" + mRecordCount+"/" + mPageCount+"pages";
                
            }
            //获取记录总数
            public function get RecordCount():int
            {
                return mRecordCount;
            }
            //打开分页控件
            public function Open():void{
                mPageIndex =0;
                OnPageChange();
            }
            //刷新当前页面
            public function Refresh():void
            {
                OnPageChange();
            }
            private function OnPageChange():void
            {
                var e:PageChangeEvent = new PageChangeEvent(mPageIndex,mPageSize);
                dispatchEvent(e);
            }
            
        ]]>
    </mx:Script>
    <mx:Label x="281" y="10" width="175" fontSize="12" id="pageinfo"/>
</mx:Canvas>

用例页面代码:

<?xml version="1.0" encoding="utf-8"?>

<mx:Application initialize="oninit()" xmlns:mx="" layout="vertical" xmlns:ns2="*">

       <mx:Script>

              <![CDATA[

                     import mx.controls.Alert;

                     import flash.events.Event;

                     private var datas:Array = new Array();

                    public function oninit():void

                     {

                            for(var i:int=0;i<40;i++)

                            {

                                   datas.push({UserName:"Henry"+i,Notes:"GuangZhou" +i})

                            }

                            pagebar1.RecordCount =datas.length;

                            pagebar1.Open();

                     }

                   public function pagechange(e:PageChangeEvent):void

                     {

                            datalist.dataProvider = e.Filter(datas)

                     }

              ]]>

       </mx:Script>

       <mx:DataGrid width="100%" id="datalist" verticalScrollPolicy="on">

              <mx:columns>

                     <mx:DataGridColumn headerText="UserName" dataField="UserName"/>

                     <mx:DataGridColumn headerText="Notes" dataField="Notes"/>

                    

              </mx:columns>

       </mx:DataGrid>

       <ns2:PageBar id="pagebar1" PageChange="pagechange(event)">

       </ns2:PageBar>

</mx:Application>

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