我使用Flutter将HTTP发布到网站以进行登录。如果仅发送数据进行登录，则HTTP-Post的响应将显示我尚未登录。我试图找出网站发送的Cookie。我用软件Postman完成的。如果添加相同的cookie，我在邮递员那里，使用Flutter的HTTP-Post可以工作，并且响应显示Im已登录。过一会儿，cookie的值切换了，并且通过Flutter的HTTP-Post起作用了。

如何从网站上获取有关cookie实际价值的信息？

代码如下：

Future initiate() async {
  ByteData bytes = await rootBundle.load('assets/Certificates/test.crt');
  SecurityContext clientContext = new SecurityContext()
    ..setTrustedCertificatesBytes(bytes.buffer.asUint8List());
  var client = new HttpClient(context: clientContext);

  IOClient ioClient = new IOClient(client);
  var form = <String,String>{
    'user':'testuser','pass':'testpass','logintype':'login','pid':'128','submit':'Anmelden','tx_felogin_pi1[noredirect]':'0'
  };
  print(form);

  var ris = await ioClient.get("https://www.test.de/login");
  print(ris.headers);
  http.Response res = await ioClient.post("https://www.test.de/login",body:form,headers: {
    "accept": "application/json","Content-Type": "application/x-www-form-urlencoded","Cookie": "fe_typo_user=12345"},encoding: Encoding.getByName("utf-8"));
  ioClient.close();
  client.close();

  print(res.body.length);
  return res.body.contains("logout");
}