微信开发 自定义菜单查询 返码乱码

string Posturl = "https://api.weixin.qq.com/cgi-bin/menu/get?access_token=Token";
//设置提交的相关参数
HttpWebRequest request = WebRequest.Create(Posturl) as HttpWebRequest;
//提交方式
request.Method = "Get";
//编码格式
request.ContentType = "text/html;charset=UTF-8";
HttpWebResponse respone = (HttpWebResponse)request.GetResponse();
StreamReader stream = new StreamReader(respone.GetResponseStream(), Encoding.UTF8);
string jsonstring = stream.ReadToEnd();

StreamReader stream = new StreamReader(respone.GetResponseStream(), Encoding.UTF8);