处理字符串格式的XML文本

        private string GetIdFromResponseText(string responseText)
        {
            string smsId = string.Empty;
            XmlDocument document = new XmlDocument();
            document.LoadXml(responseText);

            XmlNode responseNode = document.SelectSingleNode("sendResp");
            if (responseNode != null)
            {
                foreach (XmlNode node in responseNode.SelectNodes("sms"))
                {
                    XmlNode n = node.SelectSingleNode("smsID");
                    if (n != null)
                    {
                        smsId = n.InnerText;
                        break;
                    }
                }

            }
            return smsId;
        }