1. 返回DataSet格式;

/// 
        /// 向某个url提交数据并读取该地址返回的xml,并将xml转换成dataset,并返回dataset中某个表        /// 
        /// 提交的低至        /// 参数        /// 表名        /// 编码格式        /// 
             public static DataSet PostData(string url, string param, String tableName, Encoding encoding)        {
    #region post数据            DataSet ds = new DataSet(); DataTable dt = new DataTable();            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);            req.Timeout = 120000;            try            {                byte[] requestbytes = encoding.GetBytes(param);                req.Method = "post";                req.ContentType = "application/x-www-form-urlencoded";                req.ContentLength = requestbytes.Length;                System.IO.Stream requeststream = req.GetRequestStream();                requeststream.Write(requestbytes, 0, requestbytes.Length);                requeststream.Close();                HttpWebResponse res = (HttpWebResponse)req.GetResponse();                System.IO.StreamReader sr = new System.IO.StreamReader(res.GetResponseStream(), encoding);                String backstr = sr.ReadToEnd();                StringReader txtReader = new StringReader(backstr);                XmlTextReader xmlReader = new XmlTextReader(txtReader);                ds.ReadXml(xmlReader);                sr.Close();                res.Close();                sr.Dispose();            }            catch            {                return null;            }            //条件判断            //if (ds != null && ds.Tables.Count > 0 && ds.Tables[tableName] != null)            //{            //    dt = ds.Tables[tableName].Copy();            //}            if (ds != null && ds.Tables.Count > 0)            {                //  dt = ds.Tables[tableName].Copy();                return ds;            }            return ds;            #endregion        }

2. 返回字符串

string url = Config.PassportUserInfoUrl + "&userid=" + userid;//可以把链接放到配置文件中                string result = SlRequest.GetResponse(url, "");                XmlDocument doc = new XmlDocument();                doc.LoadXml(result);                XmlNode node = doc.SelectSingleNode("soufun_passport/common");//选择XML节点的值                if (node != null)                {                    string resMsg = node.SelectSingleNode("return_result").InnerText;                    if (resMsg == "100")                    {                       //此处可以定义一个User实体类, 来接收关于User的Inforeturn user;                    }                    else                    {                        errorMessage = node.SelectSingleNode("error_reason").InnerText;                        return null;                    }                 //此处讲判断某个XML节点下面有几个子节点

                   if (node.ChildNodes.Count > 3)

                   {

                        resMsg = "";

                    }

 注: C#将XMLDocument转化为String函数

/// 将XmlDocument转化为string         ///          ///          /// 
              public string ConvertXmlToString(XmlDocument xmlDoc)         {             MemoryStream stream = new MemoryStream();             XmlTextWriter writer = new XmlTextWriter(stream, null);             writer.Formatting = Formatting.Indented;             xmlDoc.Save(writer);       StreamReader sr = new StreamReader(stream, System.Text.Encoding.UTF8);             stream.Position = 0;             string xmlString = sr.ReadToEnd();             sr.Close();             stream.Close();       return xmlString;         }