public static string HttpApi(string url, string jsonstr, string type)
        {
            Encoding encoding = Encoding.UTF8;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);//webrequest请求api地址
            request.Headers.Add("command:");
            request.Headers.Add("token:");
            request.Accept = "text/html,application/xhtml+xml,*/*";
            request.ContentType = "application/json";
            request.Method = type.ToUpper().ToString();//get
            //byte[] buffer = encoding.GetBytes(jsonstr);
            //request.ContentLength = buffer.Length;
            //request.GetRequestStream().Write(buffer, 0, buffer.Length);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            {
                return reader.ReadToEnd();
            }
        }
        
        //xml
        public static string HttpXml(string url, string jsonstr, string type)
        {
            Encoding encoding = Encoding.UTF8;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);//webrequest请求api地址
            request.Accept = "text/html,application/xhtml+xml,*/*";
            request.ContentType = "application/json";
            request.Method = type.ToUpper().ToString();//get
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            {
                XmlDocument document = new XmlDocument();
                XmlReader xmlreader = XmlReader.Create(reader);
                document.Load(xmlreader);
                XmlNode node = document.SelectSingleNode("response/route/paths/path");
                return node.SelectSingleNode("distance").InnerText;
            }
        }