在JPanel中，怎么将.png格式的图片设置为背景

在JPanel中，如何将.png格式的图片设置为背景？

yourJPanel.setBackgroundDecorator(new AssetBakcground(yourImage));

 

package
{
	import flash.display.DisplayObject;
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.MouseEvent;
	import flash.filters.DropShadowFilter;
	import flash.geom.Rectangle;
	
	import org.aswing.*;
	import org.aswing.border.EmptyBorder;
	
	public class PanelBg extends Sprite{
		
		[Embed(source="icon5.png")]
		private var imgClass:Class;
		
		private var window:JWindow;
		
		public function PanelBg()
		{
			super();
			
			AsWingManager.initAsStandard(this);
			
			window = new JWindow();
			var img:DisplayObject = new imgClass() as DisplayObject;
			img.filters = [new DropShadowFilter()];
			//make some blank space leave to the img shadow
			window.setBorder(new EmptyBorder(null, new Insets(0, 0, 4, 4)));
			window.setBackgroundDecorator(new AssetBackground(img));
			//or even you can directly call addChild to append a image
			//window.addChild(img);
			
			var buttonPane:JPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
			buttonPane.appendAll(new JButton("OK"), new JButton("Cancel"));
			window.getContentPane().append(buttonPane, BorderLayout.SOUTH);
			window.getContentPane().append(new JLabel("This is a JWindow"), BorderLayout.CENTER);
			window.setSizeWH(300, 300);
			window.show();
			//simplly make the window dragable
			window.addEventListener(MouseEvent.MOUSE_DOWN, __mouseDown);
			window.addEventListener(MouseEvent.MOUSE_UP, __mouseUp);
		}
		
		private function __mouseDown(e:Event):void{
			window.startDrag(false, new Rectangle(0, 0, stage.stageWidth, stage.stageHeight));
		}
		
		private function __mouseUp(e:Event):void{
			window.stopDrag();
		}
	}
}