Dart base64編碼String

import 'dart:convert';

void main() {
  var str = "Hello world";
  var bytes = utf8.encode(str);

  var encoded1 = base64Encode(bytes);

  print(encoded1);
  print(base64Decode(encoded1));
  print(String.fromCharCodes(base64Decode(encoded1)));
}

D:\workTA\AndroidSoftware\flutter\flutter\bin\cache\dart-sdk\bin\dart.exe --enable-asserts --enable-vm-service:50345 D:\workTA\AndroidSoftware\workPlace\petreasure\petreasure\lib\cheshi.dart
Observatory listening on http://127.0.0.1:50345/

SGVsbG8gd29ybGQ=
[72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]
Hello world

Process finished with exit code 0