search_username.dart

import 'dart:convert';
import 'dart:io';

void main() async {
  final rocId = '你的身分證';
  final client = HttpClient();
  List<int> bodyBytes = utf8.encode("uid=$rocId"); // utf8 encode
  final request = await client.postUrl(
    Uri.parse('https://webap.nkust.edu.tw/nkust/system/getuid_1.jsp'),
  );
  request.headers.add('Connection', 'keep-alive');
  request.headers.add('Content-Length', "uid=$rocId".length.toString());
  request.headers.add('Content-Type', 'application/x-www-form-urlencoded');
  request.add(bodyBytes);
  final response = await request.close();
  var text = await utf8.decoder.bind(response).first;
  print(text);
}