flex CheckBoxList 自定义控件

flex CheckBoxList 在实际使用中，是拿不到选中的值。-_-#!

/**
 * @author 		
 * @date 		2010-6-2
 * @description	多选控件 
 */
package components
{
	import flash.events.Event;
	import flash.events.MouseEvent;
	
	import mx.collections.ArrayCollection;
	import mx.collections.ICollectionView;
	import mx.collections.IList;
	import mx.collections.ListCollectionView;
	import mx.collections.XMLListCollection;
	import mx.containers.Tile;
	import mx.controls.Alert;
	import mx.controls.CheckBox;
	import mx.core.IUIComponent;
	import mx.core.Repeater;
	
	public class CheckBoxList extends Tile
	{				
		protected var collection:ICollectionView;			//显示的数据源
		private var _labelField:String = "label";			//显示的数据字段
		private var _valueField : String = "value" 			//设置显示数据字段的值
		private var _dataField : String = "";				//选中的状态		
		private var _selectedItem : Object = "";			//设置选中的值
		private var _splitString : String = "，";			//设置选中值的分割符
		private var cellWidth:Number;
    	private var cellHeight:Number;
    	private var cbxArr : Array = new Array();
	    
		//数据源
		[Bindable("collectionChanged")]
		public function get dataProvider():Object
	    {
	        return collection;
	    }
	    	       
	    [Bindable("collectionChanged")]
	    public function set dataProvider(value:Object):void
	    {
	        if (value is Array)
	        {
	            collection = new ArrayCollection(value as Array);
	        }
	        else if (value is ICollectionView)
	        {
	            collection = ICollectionView(value);
	        }
	        else if (value is IList)
	        {
	            collection = new ListCollectionView(IList(value));
	        }
	        else if (value is XMLList)
	        {
	            collection = new XMLListCollection(value as XMLList);
	        }
	        else
	        {
	            // convert it to an array containing this one item
	            var tmp:Array = [value];
	            collection = new ArrayCollection(tmp);
	        }	        
	        
	        dispatchEvent(new Event("collectionChanged"));
	        addChildren();
	    }
	    //显示字段
	    [Bindable("labelFieldChanged")]
		public function get labelField():String
	    {
	        return _labelField;
	    }
	    
	    public function set labelField(value:String):void
	    {
	        _labelField = value;
	        dispatchEvent(new Event("labelFieldChanged"));
	    }
	    
	    public function get valueField() : String
	    {
	    	 return _valueField;
	    }
	    
	    public function set valueField(value:String):void
	    {
	        _valueField = value;
	    }
	    
	    //设定选中的状态
	    [Bindable("dataFieldChanged")]
	    public function get dataField() : String
	    {
	    	return _dataField;
	    }
	    public function set dataField(value : String) : void
	    {
	    	_dataField = value;
	    	dispatchEvent(new Event("dataFieldChanged"));
	    }
	    //设定选中的值
	    [Bindable("selectedValueChanged")]
	    public function get selectedItem() : Object
	    {
	    	var value : Object = new Object();
	    	value[labelField] = "";
	    	value[valueField] = "";
	    	for each (var obj : Object in cbxArr)
	    	{
	    		if(obj.selected)
	    		{
	    			value[labelField] += obj.data[labelField] + _splitString;		//显示的项
	    			value[valueField] += obj.data[valueField] + _splitString;		//值项
	    		}
	    	}
	    	return value;
	    }
	    
	    public function set selectedItem(value : Object) : void
	    {
	    	_selectedItem= value;
	    	for each(var o : Object in collection)
	        {	        	
	        	o[dataField] = "false";
	        }	      
	        if(value != null) setSelectedName();
	    	addChildren();	    	
	    	dispatchEvent(new Event("selectedValueChanged"));
	    }
	    //设定分割符
		[Bindable("splitStringChanged")]
		public function get splitString() : String
		{
			return _splitString;	
		}
		
		public function set splitString(value : String) : void
		{
			_splitString = value;
			dispatchEvent(new Event("splitStringChanged"));
		}
		
		public function CheckBoxList()
		{
			super();
		}		
		
		//新增子列表
		private function addChildren() : void
		{
			this.removeAllChildren();
			cbxArr = new Array();
			if(collection == null) return;
			
			for (var i : int =0; i < collection.length; i++)
			{
			   	var cb : CheckBox = new CheckBox();
			   	cb.selected= collection[i][dataField]=="true" ? true : false;
			   	cb.data = collection[i];
				cb.label = collection[i][labelField];	
				cbxArr.push(cb);			
				addChild(cb);		
			}
		}
		//拿到当前选中的对象列表
		public function getSelectedArrary() : Array
		{
			var arr : Array = new Array();
	    	for each (var obj : Object in collection)
	    	{
	    		if(obj[dataField] == "true")
	    			arr.push(obj);
	    	}
	    	return arr;
		}
		
		protected override function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
		{
			super.updateDisplayList(unscaledWidth,unscaledHeight);
			findCellSize();
			
			if(numChildren<=0) return ;			
			var horizontalGap:Number = getStyle("horizontalGap");
            var verticalGap:Number = getStyle("verticalGap");			
			var num : Number = Math.floor(width / (cellWidth + horizontalGap) );
			height = Math.ceil((cellHeight + verticalGap) * Math.ceil(numChildren/num));			
		}

		private function findCellSize():void
	    {
	        // If user explicitly supplied both a tileWidth and
	        // a tileHeight, then use those values.
	        var widthSpecified:Boolean = !isNaN(tileWidth);
	        var heightSpecified:Boolean = !isNaN(tileHeight);
	        if (widthSpecified && heightSpecified)
	        {
	            cellWidth = tileWidth;
	            cellHeight = tileHeight;
	            return;
	        }
	
	        // Reset the max child width and height
	        var maxChildWidth:Number = 0;
	        var maxChildHeight:Number = 0;
	        
	        // Loop over the children to find the max child width and height.
	        var n:int = numChildren;
	        for (var i:int = 0; i < n; i++)
	        {
	            var child:IUIComponent = IUIComponent(getChildAt(i));
	
	            if (!child.includeInLayout)
	                continue;
	            
	            var Number = child.getExplicitOrMeasuredWidth();
	            if (width > maxChildWidth)
	                maxChildWidth = width;
	            
	            var height:Number = child.getExplicitOrMeasuredHeight();
	            if (height > maxChildHeight) 
	                maxChildHeight = height;
	        }
	        
	        // If user explicitly specified either width or height, use the
	        // user-supplied value instead of the one we computed.
	        cellWidth = widthSpecified ? tileWidth : maxChildWidth;
	        cellHeight = heightSpecified ? tileHeight : maxChildHeight;
	    }
		
		private function setSelectedName() : void
		{					
			var arr : Array = _selectedItem.split(_splitString);
			
			for each (var obj : Object in collection)
			{
				for each(var str : String in arr)
				{
					if(obj[labelField]==str) 
						obj[dataField] = "true";
				}
			}			
		}
	}

}