flutter-单击文本字段时，键盘会隐藏自身

import 'package:flutter/material.dart';

class MyTextField extends StatefulWidget {
  @override
  _MyTextFieldState createState() => _MyTextFieldState();
}

class _MyTextFieldState extends State<MyTextField> {
  FocusNode _focusNode = FocusNode();

  @override
  void initState() {
    super.initState();
    _focusNode.addListener(_onFocusChange);
  }

  @override
  void dispose() {
    _focusNode.removeListener(_onFocusChange);
    _focusNode.dispose();
    super.dispose();
  }

  void _onFocusChange() {
    if (_focusNode.hasFocus) {
      // 聚焦时显示键盘
      FocusScope.of(context).requestFocus(FocusNode());
    } else {
      // 失焦时隐藏键盘
      FocusScope.of(context).unfocus();
    }
  }

  @override
  Widget build(BuildContext context) {
    return TextField(
      focusNode: _focusNode,
      decoration: InputDecoration(
        hintText: '点击文本字段',
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: Text('Flutter TextField'),
      ),
      body: Center(
        child: MyTextField(),
      ),
    ),
  ));
}