linq to xml 学习整理

有一段xml格式的字符串：
 string  xmlStr=  @"  <?xml version='1.0' encoding='UTF-8'?>
                             <result status='ok'>
                                 <order id='5322' policyId='100' orderNo='abc' contactMob='13012313'>
                                     <passenger name='王五'  cardNum='12******31'></passenger>
                                     <passenger name='赵六'  cardNum='12******32'></passenger>
                                 </order>
                                 <order id='5323' policyId='100' orderNo='def' contactMob='13012314'>
                                     <passenger name='张一'  cardNum='12******31'></passenger>
                                     <passenger name='李二'  cardNum='12******32'></passenger>
                                 </order>
                                 <order id='5324' policyId='200' orderNo='ghi' contactMob='13012315'>
                                     <passenger name='钱三'  cardNum='12******31'></passenger>
                                     <passenger name='孙四'  cardNum='12******32'></passenger>
                                 </order>  
                             </result>";

现要求查询出policyId=100的passger相关信息,以orderNo/name/contactMob/cardNum格式输出,

传统的解析方式：

  XmlDocument xd = new XmlDocument();
            xd.LoadXml(url);
            if (!Equals(xd.SelectNodes("result")[0], null) && xd.SelectNodes("result")[0].Attributes["status"].Value == "ok")
            {
                XmlNodeList list = xd.DocumentElement.SelectNodes("//order[@policyId='100']");//得到订单中policyId字段为100的所有order节点
                foreach (XmlElement xe in list)
                {
                    foreach (XmlElement xet in xe.GetElementsByTagName("passenger")) //得到order中的所有passenger节点
                    {
                        serverOrderMessage += xe.Attributes["orderNo"].Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += xet.Attributes["name"].Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += xe.Attributes["contactMob"].Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += xet.Attributes["cardNum"].Value;

　　　　　　　　 Response.Write("<script> alert('" + serverOrderMessage.ToString() + "')</script>");
                    }
                }
            }

用 linq to xml 解析：

 //XDocument xd = XDocument.Parse(url);   

XElement xmlPage = XElement.Parse(url);
            string serverOrderMessage = string.Empty;
            if (!Equals(xmlPage, null) && xmlPage.Attribute("status").Value == "ok")
            {
                var orders = from o in xmlPage.Descendants("order")
                                  where o.Attribute("policyId").Value.Equals("100")                           
                                  select o;                                                           //得到订单中policyId字段为100的所有order节点
       
                foreach (var order in orders)
                {
                    var passengers = from p in order.Descendants("passenger") //得到order中的所有passenger节点
                                             select p;
                    foreach(var passenger in passengers)
                    {                      
                        serverOrderMessage += order.Attribute("orderNo").Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += passenger.Attribute("name").Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += order.Attribute("contactMob").Value;
                        serverOrderMessage += "/";
                        serverOrderMessage += passenger.Attribute("cardNum").Value;        

                        Response.Write("<script> alert('" + serverOrderMessage.ToString() + "')</script>");
                    }
                }
            }

XDocument和XElement对象都通过Parse方法来加载xml格式的字符串,通过load方法加载xml文档,关于两者的区别,参看msdn:

http://msdn.microsoft.com/zh-cn/library/bb675196%28v=vs.90%29.aspx