1.在pubspec.yaml中加入依赖

fluttertoast: ^3.0.3

2.更新依赖

3.导入依赖

import 'package:fluttertoast/fluttertoast.dart';

4.在common.dart中实现显示Toast的函数，然后调用即可。

showErrorToast(String msg){
  Fluttertoast.showToast(
    msg:msg,
    toastLength: Toast.LENGTH_SHORT,
    gravity: ToastGravity.CENTER,
    timeInSecForIos: 1,
    backgroundColor: Colors.red,
    textColor: Colors.white,
    fontSize: 16.0
  );
}

showCorrectToast(String msg){
  Fluttertoast.showToast(
    msg:msg,
    toastLength: Toast.LENGTH_SHORT,
    gravity: ToastGravity.CENTER,
    timeInSecForIos: 1,
    backgroundColor: Colors.green,
    textColor: Colors.white,
    fontSize: 16.0
  );
}