如果charCode（0）是零，你能得到文本字段并执行一个条件where吗？

var tf:TextField = new TextField();

    public function Main() 
    {
        tf.addEventListener(KeyboardEvent.KEY_DOWN, onkeydown);
        addChild(tf);
    }

    private function onkeydown(e:Event):void 
    {
        if (tf.text.charAt(0) == "0")
        {
            //Create an alert, snip the text field, cause a stackovereflow.
            //Maybe hack the computer for bitcoins just because.
        }
    }