Flex 4通过重写DataGridColumn和CheckBox类给DataGrid添加选择列-CheckBoxColumn

最近在尝试着用Flex做个文件按管理的工具，在文件列表中为了操作方便，想到了再列表控件DataGird中添加一个含有复选框的列，在表头的复选框可以实现全选功能，但DataGird自身并无此功能。参照网上的相关资料，总算折腾出来了，现把源码奉上，希望对需要的朋友有点帮助，不足之处也请高手指点。

最终的CheckBoxColumn包包含四个相关的类文件，分别是：

1、CenterCheckBox.as：通过重写CheckBox基类来实现复选框的居中显示；

2、CheckBoxColumn.as：继承自DataGridColumn的一个新类，为了实现需要，增添了几个新属性；

3、CheckBoxHeaderRenderer.as：继承自CenterCheckBox 类，用于DataGrid表头的复选框，实现全选功能；

4、CheckBoxItemRenderer.as：继承自CenterCheckBox 类，用于DataGrid表中的数据行；

各文件源码如下：
1、CenterCheckBox.as


   1. package Common.YotuoUpload.CheckBoxColumn
   2. {
   3.     import flash.display.DisplayObject;  
   4.     import mx.controls.CheckBox;  
   5.     import flash.text.TextField;  
   6.     
   7.     public class CenterCheckBox extends CheckBox  
   8.     {  
   9.         // 居中展现  
  10.         override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void  
  11.         {  
  12.             super.updateDisplayList(unscaledWidth, unscaledHeight);  
  13.             var n:int = numChildren;  
  14.             for(var i:int = 0; i < n; i++)  
  15.             {  
  16.                 var c:DisplayObject = getChildAt(i);  
  17.                 if( !(c is TextField))  
  18.                 {  
  19.                     c.x = Math.round((unscaledWidth - c.width) / 2);  
  20.                     c.y = Math.round((unscaledHeight - c.height) /2 );  
  21.                 }  
  22.             }  
  23.         }  
  24.     }
  25. } 

2、DataGridColumn.as


   1. package Common.YotuoUpload.CheckBoxColumn
   2. {
   3.     import mx.controls.dataGridClasses.DataGridColumn;
   4.     
   5.     public class CheckBoxColumn extends DataGridColumn{
   6.         
   7.         public var cloumnSelected:Boolean=false;//保存该列是否全选的属性（用户先点击全选后在手动的取消几行数据的选中状态时，这里的状态不会改变）          
   8.         
   9.         public var selectItems:Array = new Array();//用户保存用户选中的数据
  10.         
  11.     
  12.         public function CheckBoxColumn(columnName:String=null){
  13.             super(columnName); 
  14.         }
  15.     }
  16. } 

3、CheckBoxHeaderRenderer.as


   1. package Common.YotuoUpload.CheckBoxColumn
   2. {
   3.     import flash.events.Event;
   4.     
   5.     import mx.collections.ArrayCollection;
   6.     import mx.controls.CheckBox;
   7.     import mx.controls.DataGrid;
   8. 
   9.     public class CheckBoxHeaderRenderer extends CenterCheckBox{   
  10.         
  11.         private var _data:CheckBoxColumn;//定义CheckBox列对象     
  12.         public function CheckBoxHeaderRenderer(){
  13.             super();
  14.             this.addEventListener(Event.CHANGE,onChange);//CheckBox状态变化时触发此事件
  15.             this.toolTip = "全选";
  16.         }
  17.         
  18.         
  19.         override public function get data():Object{
  20.             return _data;//返回的是CheckBox列的对象
  21.             
  22.         }
  23.         
  24.         override public function set data(value:Object):void{
  25.             _data = value as CheckBoxColumn;
  26.             //trace(_data.cloumnSelected);
  27.             selected = _data.cloumnSelected;
  28.         }
  29.         
  30.         private function onChange(event:Event):void{                
  31.             
  32.             var dg:DataGrid = DataGrid(listData.owner);//获取DataGrid对象
  33.             var column:CheckBoxColumn = dg.columns[listData.columnIndex];//获取整列的显示对象
  34.             
  35.             var dgDataArr:ArrayCollection = dg.dataProvider as  ArrayCollection;
  36.             
  37.             column.cloumnSelected = this.selected;//更改列的全选状态
  38.             
  39.             column.selectItems = new Array();//重新初始化用于保存选中列的对象
  40.             
  41.             if(this.selected){//如果为全部选中的化就将数据源赋值给column.selectItems，不是就不管他，上一步已经初始化为空
  42.                 column.selectItems = (dg.dataProvider as ArrayCollection).toArray();
  43.                 
  44.             }
  45.             if(dgDataArr.length>0){
  46.                 if(dgDataArr[0]!=""){
  47.                     for(var i:int = 0; i < dgDataArr.length ; i++){
  48.                         Object(dgDataArr[i]).dgSelected = this.selected;//更改没一行的选中状态
  49.                     } 
  50.                 }  
  51.             } 
  52.             dgDataArr.refresh();//刷新数据源，达到强制更新页面显示效果的功能，防止在使用时没有在VO类中使用绑定而出现点击全选页面没有更改状态的错误      
  53.         }
  54.     }
  55. } 

4、CheckBoxItemRenderer.as


   1. package Common.YotuoUpload.CheckBoxColumn
   2. {
   3.     import flash.events.Event;
   4.     import flash.events.MouseEvent;
   5.     import mx.controls.CheckBox;
   6.     import mx.controls.DataGrid;
   7.     
   8.     public class CheckBoxItemRenderer extends CenterCheckBox{
   9.         private var currentData:Object; //保存当前一行值的对象
  10. 
  11.         public function CheckBoxItemRenderer(){
  12.             super();
  13.             this.addEventListener(Event.CHANGE,onClickCheckBox);
  14.             this.toolTip = "选择";
  15.         }
  16.         
  17.         override public function set data(value:Object):void{
  18.             this.selected = value.dgSelected;
  19.             this.currentData = value; //保存整行的引用
  20.         }
  21.         
  22.         //点击check box时，根据状况向selectedItems array中添加当前行的引用，或者从array中移除
  23.         private function onClickCheckBox(e:Event):void{ 
  24.             var dg:DataGrid = DataGrid(listData.owner);//获取DataGrid对象
  25.             var column:CheckBoxColumn = dg.columns[listData.columnIndex];//获取整列的显示对象
  26.             var selectItems:Array = column.selectItems;
  27.             this.currentData.dgSelected = this.selected;//根据是否选中的状态，更改数据源中选中的标记
  28.             if(this.selected){
  29.                 selectItems.push(this.currentData);
  30.             }else{
  31.                 for(var i:int = 0; i<selectItems.length; i++){
  32.                     if(selectItems[i] == this.currentData){
  33.                         selectItems.splice(i,1)
  34.                     }
  35.                 }
  36.             }
  37.         }
  38.     }
  39. } 

调用示例：

1、在mxml中作为控件调用：


   1. <?xml version="1.0" encoding="utf-8"?> 
   2. <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"  
   3.                xmlns:s="library://ns.adobe.com/flex/spark"  
   4.                xmlns:mx="library://ns.adobe.com/flex/halo" minWidth="1024" minHeight="768"
   5.                xmlns:CheckBoxColumn="Common.YotuoUpload.CheckBoxColumn.*"
   6.                creationComplete="Init()"> 
   7.     <fx:Script> 
   8.         <![CDATA[ 
   9.             import Common.YotuoUpload.CheckBoxColumn.CheckBoxHeaderRenderer; 
  10.             import Common.YotuoUpload.CheckBoxColumn.CheckBoxItemRenderer; 
  11.             import mx.collections.ArrayCollection; 
  12.              
  13.             public var dataArray:ArrayCollection = new ArrayCollection; 
  14.              
  15.             private function Init():void{ 
  16.                 dataArray.addItem({isSelected:false,name:'Christina Coenraets',phone:'555-219-2270',email:'[email protected]'}); 
  17.                 dataArray.addItem({isSelected:false,name:'Joanne Wall',phone:'555-219-2012',email:'[email protected]'}); 
  18.                 dataArray.addItem({isSelected:false,name:'Maurice Smith',phone:'555-219-2012',email:'[email protected]'}); 
  19.                 dataArray.addItem({isSelected:false,name:'Mary Jones',phone:'555-219-2000',email:'[email protected]'}); 
  20.                 dataArray.addItem({isSelected:false,name:'God Win',phone:'555-219-2005',email:'[email protected]'}); 
  21.                 dgUser.dataProvider = dataArray; 
  22.             } 
  23.         ]]> 
  24.     </fx:Script> 
  25.     <mx:DataGrid id="dgUser" x="10" y="10" width="450" height="200"> 
  26.         <mx:columns> 
  27.             <CheckBoxColumn:CheckBoxColumn dataField="isSelected" width="25"   
  28.                                            draggable="false" resizable="false" sortable="false"
  29.                                            headerRenderer="{new ClassFactory(CheckBoxHeaderRenderer)}"
  30.                                            itemRenderer="{new ClassFactory(CheckBoxItemRenderer)}"
  31.                                            /> 
  32.             <mx:DataGridColumn headerText="姓名" dataField="name"/> 
  33.             <mx:DataGridColumn headerText="电话" dataField="phone"/> 
  34.             <mx:DataGridColumn headerText="邮件" dataField="email"/> 
  35.         </mx:columns> 
  36.     </mx:DataGrid> 
  37. </s:Application> 

2、通过代码动态调用：


   1. <?xml version="1.0" encoding="utf-8"?> 
   2. <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"  
   3.                xmlns:s="library://ns.adobe.com/flex/spark"  
   4.                xmlns:mx="library://ns.adobe.com/flex/halo" minWidth="1024" minHeight="768"
   5.                creationComplete="Init()"> 
   6.     <fx:Script> 
   7.         <![CDATA[ 
   8.             import mx.controls.dataGridClasses.DataGridColumn; 
   9.             import Common.YotuoUpload.CheckBoxColumn.CheckBoxColumn; 
  10.             import Common.YotuoUpload.CheckBoxColumn.CheckBoxHeaderRenderer; 
  11.             import Common.YotuoUpload.CheckBoxColumn.CheckBoxItemRenderer; 
  12.             import mx.collections.ArrayCollection; 
  13.              
  14.             public var dataArray:ArrayCollection = new ArrayCollection; 
  15.              
  16.             private function Init():void{ 
  17.                 dataArray.addItem({isSelected:false,name:'Christina Coenraets',phone:'555-219-2270',email:'[email protected]'}); 
  18.                 dataArray.addItem({isSelected:false,name:'Joanne Wall',phone:'555-219-2012',email:'[email protected]'}); 
  19.                 dataArray.addItem({isSelected:false,name:'Maurice Smith',phone:'555-219-2012',email:'[email protected]'}); 
  20.                 dataArray.addItem({isSelected:false,name:'Mary Jones',phone:'555-219-2000',email:'[email protected]'}); 
  21.                 dataArray.addItem({isSelected:false,name:'God Win',phone:'555-219-2005',email:'[email protected]'}); 
  22.                  
  23.                 var _checkBoxCloumn:CheckBoxColumn = new CheckBoxColumn(); 
  24.                 _checkBoxCloumn.dataField = "isSelected"; 
  25.                 _checkBoxCloumn.headerRenderer = new ClassFactory(CheckBoxHeaderRenderer); 
  26.                 _checkBoxCloumn.itemRenderer = new ClassFactory(CheckBoxItemRenderer); 
  27.                 _checkBoxCloumn.width = 30; 
  28.                 _checkBoxCloumn.sortable = false; 
  29.                 _checkBoxCloumn.draggable = false; 
  30.                  
  31.                 var _nameColumn:DataGridColumn = new DataGridColumn(); 
  32.                 _nameColumn.headerText = "姓名"; 
  33.                 _nameColumn.dataField = "name"; 
  34.                  
  35.                 var _telColumn:DataGridColumn = new DataGridColumn(); 
  36.                 _telColumn.headerText = "电话"; 
  37.                 _telColumn.dataField = "phone"; 
  38.                  
  39.                 var _emailColumn:DataGridColumn = new DataGridColumn(); 
  40.                 _emailColumn.headerText = "邮件"; 
  41.                 _emailColumn.dataField = "email"; 
  42.                  
  43.                 dgUser.columns = new Array(_checkBoxCloumn,_nameColumn,_telColumn,_emailColumn); 
  44.                 dgUser.dataProvider = dataArray; 
  45.             } 
  46.         ]]> 
  47.     </fx:Script> 
  48.     <mx:DataGrid id="dgUser" x="10" y="10" width="450" height="200" /> 
  49. </s:Application> 

PS：该组件要求在数据源中存在属性isSelected（Boolean类型，用来记录当前行是否被选中）属性，这样就限制了程序的通用性，试了很多方法都未很好解决，希望有办法解决的朋友给以指点。