flutter TextField粘滞，当我完成其他项目时，光标会跳回它

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

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

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

  @override
  Widget build(BuildContext context) {
    return TextField(
      focusNode: _focusNode,
      decoration: InputDecoration(
        labelText: 'Enter text',
      ),
    );
  }
}

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

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

  @override
  Widget build(BuildContext context) {
    return TextField(
      focusNode: _focusNode,
      decoration: InputDecoration(
        labelText: 'Enter text',
      ),
      onEditingComplete: () {
        FocusScope.of(context).requestFocus(FocusNode());
      },
    );
  }
}