假设您的服务器期望username:password组合将其编码为UTF-8（有关更多详细信息，请参阅RFC
7617），然后使用以下命令：

import 'dart:convert';

import 'package:http/http.dart';

main() async {
  String username = 'test';
  String password = '123£';
  String basicAuth =
      'Basic ' + base64Encode(utf8.encode('$username:$password'));
  print(basicAuth);

  Response r = await get('https://api.somewhere.io',
      headers: <String, String>{'authorization': basicAuth});
  print(r.statusCode);
  print(r.body);
}