添加鼠标事件 ----简单画图程序

package {
import flash.display.Sprite;
import flash.events.MouseEvent;
[SWF(width="800",height="600",backgroundColor="#ffffff",frameRate="56")]
public class example extends Sprite
{
private var _sprite:Sprite;

public function example()
{
_sprite = new Sprite();
addChild(_sprite);
_sprite.graphics.beginFill(0xffffff);
_sprite.graphics.drawRect(0,0,400,400);
_sprite.graphics.endFill();

_sprite.addEventListener(MouseEvent.MOUSE_DOWN,onMouseDown);
_sprite.addEventListener(MouseEvent.MOUSE_UP,onMouseUp);

}

private function onMouseDown(event:MouseEvent):void{
_sprite.graphics.lineStyle(1,0,1);
_sprite.graphics.moveTo(mouseX,mouseY);
_sprite.addEventListener(MouseEvent.MOUSE_MOVE,onMouseMove);
}

private function onMouseUp(event:MouseEvent):void{
_sprite.removeEventListener(MouseEvent.MOUSE_OVER,onMouseMove);
}

private function onMouseMove(event:MouseEvent):void{
_sprite.graphics.lineTo(mouseX,mouseY);
}
}
}