当flutter使用dio请求时，如何将shared_preferences中的值添加到令牌中

dependencies:
  dio: ^3.0.10
  shared_preferences: ^2.0.7

import 'package:dio/dio.dart';
import 'package:shared_preferences/shared_preferences.dart';

String token = '';
SharedPreferences prefs = await SharedPreferences.getInstance();
if (prefs.containsKey('token')) {
  token = prefs.getString('token') ?? '';
}

var dio = Dio();
dio.options.headers['Authorization'] = 'Bearer $token';

Response response = await dio.get('https://example.com/api');

import 'package:dio/dio.dart';
import 'package:shared_preferences/shared_preferences.dart';

void makeRequest() async {
  String token = '';
  SharedPreferences prefs = await SharedPreferences.getInstance();
  if (prefs.containsKey('token')) {
    token = prefs.getString('token') ?? '';
  }

  var dio = Dio();
  dio.options.headers['Authorization'] = 'Bearer $token';

  try {
    Response response = await dio.get('https://example.com/api');
    // 处理网络请求结果
    print(response.data);
  } catch (e) {
    // 处理异常
    print(e.toString());
  }
}