如何像在文本字段中那样在dropdownbutton中添加标签文本？

import 'package:flutter/material.dart';

class TagDropdownButton extends StatefulWidget {
  @override
  _TagDropdownButtonState createState() => _TagDropdownButtonState();
}

class _TagDropdownButtonState extends State<TagDropdownButton> {
  List<String> selectedTags = [];

  @override
  Widget build(BuildContext context) {
    return Wrap(
      spacing: 8.0,
      children: <Widget>[
        DropdownButton<String>(
          value: null,
          hint: Text('选择标签'),
          onChanged: (String newValue) {
            setState(() {
              selectedTags.add(newValue);
            });
          },
          items: List.generate(
            tags.length,
            (index) => DropdownMenuItem<String>(
              value: tags[index],
              child: Text(tags[index]),
            ),
          ),
        ),
        ...selectedTags.map(
          (tag) => Chip(
            label: Text(tag),
            onDeleted: () {
              setState(() {
                selectedTags.remove(tag);
              });
            },
          ),
        ),
      ],
    );
  }
}

List<String> tags = [
  '标签1',
  '标签2',
  '标签3',
  '标签4',
  '标签5',
];

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: Text('DropdownButton with Tags'),
      ),
      body: Center(
        child: TagDropdownButton(),
      ),
    ),
  ));
}