private string HttpGet(string api)
    {
      string serviceAddress = api;
      HttpWebRequest request = (HttpWebRequest)WebRequest.Create(serviceAddress);
      request.Method = "GET";
      request.ContentType = "text/html;charset=UTF-8";
      HttpWebResponse response = (HttpWebResponse)request.GetResponse();
      Stream myResponseStream = response.GetResponseStream();
      StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.UTF8);
      //返回json字符串
      return myStreamReader.ReadToEnd();
    }

 Task task1 = new Task(() =>
    {
      string response = HttpGet("http://172.16.0.239:9002/lg.php?action=checkNotice");
      this.Invoke((MethodInvoker)(() =>//子線程中操作UI
      {
        label1.Text = response;//于程序界面顯示
      }));
      Console.WriteLine(response);//于控制臺(tái)打印
    });
   task1.Start();

JObject json = (JObject)JsonConvert.DeserializeObject(response);
Console.WriteLine(json);
Console.WriteLine(json["code"]);
Console.WriteLine(json["content"]);