public static string DataSetToXmlString(DataTable Data)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                Data.WriteXml(stream);
                stream.Position = 0;
                using (TextReader reader = new StreamReader(stream))
                {
                    return reader.ReadToEnd();
                }
            }
        }

   public static string Dtb2Json(DataTable dtb)
        {
          JavaScriptSerializer jss = new JavaScriptSerializer();
           System.Collections.ArrayList dic = new System.Collections.ArrayList();
            foreach (DataRow dr in dtb.Rows)
             {
                 System.Collections.Generic.Dictionary<string, object> drow = new System.Collections.Generic.Dictionary<string, object>();
               foreach (DataColumn dc in dtb.Columns)
                 {
                     drow.Add(dc.ColumnName, dr[dc.ColumnName]);
                }
                dic.Add(drow);
 
             }
             //序列化  
             return jss.Serialize(dic);
       }