[转] 倒计时抢答

package {        import flash.display.Sprite;        import flash.events.Event;        import flash.events.KeyboardEvent;        import flash.events.MouseEvent;        import flash.events.TimerEvent;        import flash.utils.Timer;                /**         * @author FLASH023         * @date 2011-5-4 24:14        **/        public class JBKey extends Sprite          {                private var timer:Timer;                private var time:uint;                public function JBKey():void {                        timer = new Timer(1000);                        timer.addEventListener (TimerEvent.TIMER , onTimer);                        reset_btn.addEventListener (MouseEvent.CLICK, onClick);                        onClick(null);                }                                private function onClick(e:MouseEvent):void                 {                        time = 10;                        timer.reset();                        timer.start ();                                        reset_btn.enabled = false;                        key_txt.text = "";                }                                private function onTimer(e:TimerEvent ):void                 {                        time_txt.text = --time+"";                        if (time <= 0) {                                timer.stop();                                reset_btn.enabled = true;                                stage.addEventListener (KeyboardEvent.KEY_DOWN, kewDown);                        }                }                                private function kewDown(e:KeyboardEvent):void                 {                        key_txt.text = String.fromCharCode(e.keyCode)+"";                        //                                                stage.removeEventListener (KeyboardEvent.KEY_DOWN, kewDown);                }        }        }