点击ok后获取到ok的事件  ~~~ async 将一个方法变成异步，总是和await 一起使用 ~~~ ~~~ import 'package:flutter/material.dart'; class AlertDemo extends StatefulWidget { @override _AlertDemoState createState() => _AlertDemoState(); } class _AlertDemoState extends State<AlertDemo> { _alertDialog() async{ var result = await showDialog( context: context, builder: (context){ return AlertDialog( title: Text('aa'), content: Text('AAAA?'), actions: <Widget>[ RaisedButton( child: Text('ok'), onPressed: (){ Navigator.pop(context,'ok'); } ), RaisedButton( child: Text('close'), onPressed: (){ } ), ], ); } ); print(result); return result; } _simpleDialog() async{ } _modelBottomSheet() async{ } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('Alert'), ), body: Column( mainAxisAlignment: MainAxisAlignment.center, crossAxisAlignment: CrossAxisAlignment.center, children: <Widget>[ RaisedButton( child: Text('_alertDialog'), onPressed: _alertDialog ), SizedBox(height: 20), RaisedButton( child: Text('_simpleDialog'), onPressed: _simpleDialog ), SizedBox(height: 20), RaisedButton( child: Text('_modelBottomSheet'), onPressed: _modelBottomSheet ), SizedBox(height: 20), ], ), ); } } ~~~ ***** 自定义Alert  使用  // 定时关闭