flutter如何让输入框软键盘自动上移

import 'package:flutter/material.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Builder(
          builder: (context) => Padding(
            padding: EdgeInsets.only(bottom: MediaQuery.of(context).viewInsets.bottom),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                TextField(),
                RaisedButton(
                  child: Text('Submit'),
                  onPressed: () {},
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}