在表单外单击后，移除textForm field Flutter Web上的焦点

import 'package:flutter/material.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  FocusNode _focusNode = FocusNode();

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        _focusNode.unfocus(); // 移除焦点
      },
      child: Scaffold(
        body: Center(
          child: TextFormField(
            focusNode: _focusNode,
            decoration: InputDecoration(
              labelText: 'Text',
            ),
          ),
        ),
      ),
    );
  }
}