如何用c＃在asp.net中读取在线xml节点 [英] How to read online xml node in asp.net with c#

问题描述

您好，



我想通过此在线xml阅读国家/地区节点：



http://ws.cdyne.com /ip2geo/ip2geo.asmx/ResolveIP?IPaddress=49.14.147.196&LicenseKey=0 [ ^ ]



见我试过的内容 -

 XmlDocument document =  new  XmlDocument（）; 
 document.Load（  http://ws.cdyne.com/ip2geo/ip2geo.asmx/ResolveIP ？名称IP地址= 49.14.147.196&安培; LICENSEKEY = 0\" ）; 
 XmlNode node = document.SelectSingleNode（  / IPInformation / Country）; 
  string  name = node.InnerText; 

但不是成功，在字符串名称中获取错误 - 对象引用未设置为对象的实例，XmlNode节点也为空。

解决方案

返回的XML文档具有默认命名空间。不幸的是， XmlDocument 并不容易选择具有默认命名空间的节点。您需要创建 XmlNamespaceManager ，为默认命名空间添加名称空间前缀，并更改XPath表达式以使用新的名称空间前缀：

< pre lang =cs> XmlDocument document = new XmlDocument（）;
document.Load（ http://ws.cdyne.com/ip2geo/ip2geo.asmx/ResolveIP ？名称IP地址= 49.14.147.196&安培; LICENSEKEY = 0\" ）;

XmlNamespaceManager namespaceManager = new XmlNamespaceManager（document.NameTable）;
namespaceManager.AddNamespace（ x，document.DocumentElement.NamespaceURI）;

XmlNode node = document.SelectSingleNode（ / x：IPInformation / x：Country，namespaceManager）;
string name = node.InnerText;

Hi There,

I want to read Country node from this online xml :

http://ws.cdyne.com/ip2geo/ip2geo.asmx/ResolveIP?IPaddress=49.14.147.196&LicenseKey=0[^]

See What I Tried -

XmlDocument document = new XmlDocument();
document.Load("http://ws.cdyne.com/ip2geo/ip2geo.asmx/ResolveIP?IPaddress=49.14.147.196&LicenseKey=0"); 
XmlNode node = document.SelectSingleNode("/IPInformation/Country");
string name = node.InnerText;

But not succeeded, Getting Error in string name - Object reference not set to an instance of an object, XmlNode node is also null.

解决方案

The returned XML document has a default namespace. Unfortunately, the XmlDocument doesn't make it easy to select nodes with a default namespace. You need to create an XmlNamespaceManager, add a namespace prefix for the default namespace, and change your XPath expression to use the new namespace prefix:

XmlDocument document = new XmlDocument();
document.Load("http://ws.cdyne.com/ip2geo/ip2geo.asmx/ResolveIP?IPaddress=49.14.147.196&LicenseKey=0"); 

XmlNamespaceManager namespaceManager = new XmlNamespaceManager(document.NameTable);
namespaceManager.AddNamespace("x", document.DocumentElement.NamespaceURI);

XmlNode node = document.SelectSingleNode("/x:IPInformation/x:Country", namespaceManager);
string name = node.InnerText;

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