c# streamReader转XmlDocument读取节点

http获得web（url）请求，先是获得数据流streamreader，之后将String数据流转换为xmldocument，之后xmlnode读取节点。

                // get the response
                WebResponse webResponse = webRequest.GetResponse();
                if (webResponse == null)
                { return null; }
                //需要将返回的编码进行指定，指定成默认的即可
                StreamReader sr = new StreamReader(webResponse.GetResponseStream(), System.Text.Encoding.UTF8);
                string streamString = sr.ReadToEnd().Trim().Replace("\n", "");//去掉换行符
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(streamString);//加载文档
                XmlNode test1 = doc.SelectSingleNode("returnsms");//根节点
                string aaa = test1.SelectSingleNode("returnstatus").InnerText;//子节点