单击关闭后清除TextFormField

import 'package:flutter/material.dart';

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  TextEditingController _controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Form'),
      ),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Column(
          children: [
            TextFormField(
              controller: _controller,
              decoration: InputDecoration(
                labelText: 'Input',
              ),
            ),
            SizedBox(height: 16.0),
            RaisedButton(
              onPressed: () {
                setState(() {
                  _controller.clear();
                });
              },
              child: Text('关闭并清除'),
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyForm(),
  ));
}