简单的物体二段跳效果

非常非常简单的效果，按任意键进行方块的跳跃，有二段跳效果和轻跳和重跳效果，根据按键长短判定的。这是在兄弟会论坛做的一道题，很应该转来跟大家分享下～
 
代码如下：
package {
/*author : CYPL*/
        import flash.display.*;
        import flash.events.*;
        import flash.utils.Timer;
        public class JumpTest extends Sprite {
                private static  const G:int=1;
                private var box:Sprite;
                private var landObject:Sprite;
                private var ySpeed:int=0;
                private var jumpSpeed:int=-15;
                private var keyPressed:Boolean= false;
                private var keyReleased:Boolean=true;
                private var comboJump:Boolean=false;
                private var inAir:Boolean=true;
                private var timer:Timer;
                public function JumpTest() {
                        box=drawRect((stage.stageWidth-50)/2,100,50,50,0xff0000);
                        landObject=drawRect(0,300,stage.stageWidth,20);
                        (timer=new Timer(30)).start();
                        configureControl();
                }
                private function configureControl():void {
                        stage.addEventListener(KeyboardEvent.KEY_DOWN,keyDownHandler,false,0,true);
                        stage.addEventListener(KeyboardEvent.KEY_UP,keyUpHandler,false,0,true);
                        timer.addEventListener(TimerEvent.TIMER,timerHandler,false,0,true);
                }
                private function drawRect(posX:Number,posY:Number,w:Number,h:Number,color:uint=0):Sprite {
                        var rect:Sprite;
                        with (rect=new Sprite) {
                                graphics.beginFill(color);
本文转自：http://www.5uflash.com/flashjiaocheng/Flashaschengxu/2988.html