import 'dart:async';

 class _LoginPagestate extends State<LOGinPage> {  ...  Timer _timer;  int _countdownTime = 0;  ... }

 Gesturedetector(  onTap: () {   if (_countdownTime == 0 && validatemobile()) {    //Http请求发送验证码    ...    setState(() {     _countdownTime = 60;    });    //开始倒计时    startCountdownTimer();   }  },  child: Text(   _countdownTime > 0 ? '$_countdownTime后重新获取' : '获取验证码',   style: TextStyle(    fontSize: 14,    color: _countdownTime > 0      ? Color.FromargB(255, 183, 184, 195)      : Color.fromARGB(255, 17, 132, 255),   ),  ), )

 void startCountdownTimer() {  const oneSec = const Duration(seconds: 1);   VAR callback = (timer) => {   setState(() {    if (_countdownTime < 1) {     _timer.cancel();    } else {     _countdownTime = _countdownTime - 1;    }   })  };   _timer = Timer.periodic(oneSec, callback); }

 @override void dispose() {  super.dispose();  if (_timer != null) {   _timer.cancel();  } }