遷移問題，在AS3.0中，onkeydown事件處理函數(shù)不是有Flashplayer在運(yùn)行時(shí)自動(dòng)觸發(fā)的。必須首先使用addEventListener('keyDown',callback_handler)這是什么意思？addEventListener('keyDown',callback_handler)是什么意思？具體要怎么使用？本人的源程序：package{import flash.display.MovieClip;import flash.events.KeyboardEvent;import flash.ui.Keyboard;public class Main_Character extends MovieClip{public function Main_Character(){init();}function inin():void{stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);}function onKeyDown(event:KeyboardEvent):void{if (event.keyCode == Keyboard.LEFT){player.x -= 10;}if (event.keyCode == Keyboard.RIGHT){player.x += 10;}if (event.keyCode == Keyboard.DOWN){player.y += 10;}if (event.keyCode == Keyboard.UP){player.y -= 10;}}}}