<?xml version="1.0"?>
<aws:UrlInfoResponse xmlns:aws="http://alexa.amazonaws.com/doc/2005-10-05/">
 <aws:Response xmlns:aws="http://awis.amazonaws.com/doc/2005-07-11">
  <aws:UrlInfoResult>
<aws:Alexa>
<aws:ContactInfo>
<aws:Email>[email protected]</aws:Email>
</aws:ContactInfo>
<aws:Alexa>
  </aws:UrlInfoResult>
 </aws:Response>
</aws:UrlInfoResponse>
假如你要取得<aws:Email>节点，诶，你发现<aws:UrlInfoResponse>和<aws:Response>节点的命名空间马甲是一样的。

这个时候怎么办呢？难道是添加两次aws命名空间？其实不然。做法如下：

1.我们只要添加<aws:Response>节点的命名空间。

xnm.AddNamespace("aws", "http://awis.amazonaws.com/doc/2005-07-11");

2.取得根节点，这样我们就可以忽略根结点的命名空间，然后应用XPath取得你想要的节点。

XmlElement xe = xd.DocumentElement;
XmlNodeList xnl = xe.SelectNodes(
"//aws:Response/aws:UrlInfoResult/aws:Alexa/aws:ContactInfo/aws:Email", xnm);

直接这样取好像也可以：

XmlNodeList xnl = xd.SelectNodes(
"//aws:Response/aws:UrlInfoResult/aws:Alexa/aws:ContactInfo/aws:Email", xnm);

这样我们就可以得到<aws:Email>节点了，然后打印出来

foreach (XmlNode xn1 in xnl)
{
Response.Write(xn1.InnerXml.ToString() + "</br>");
}

完整代码：

XmlDocument xd = new XmlDocument();
xd.Load(Server.MapPath(".")+"/a.xml");
XmlNamespaceManager xnm = new XmlNamespaceManager(xd.NameTable);
xnm.AddNamespace("aws", "http://awis.amazonaws.com/doc/2005-07-11");
XmlElement xe = xd.DocumentElement;
XmlNodeList xnl = xe.SelectNodes(
"//aws:Response/aws:UrlInfoResult/aws:Alexa/aws:ContactInfo/aws:Email", xnm);
//XmlNodeList xnl = xd.SelectNodes(
//"//aws:Response/aws:UrlInfoResult/aws:Alexa/aws:ContactInfo/aws:Email", xnm);
foreach (XmlNode xn1 in xnl)
{
Response.Write(xn1.InnerXml.ToString() + "</br>");
}

--------------------------------------------------------

譬如要讀到DataSet中，如：

               XmlDocument doc = new XmlDocument();

                doc.Load(filename);

                XmlNamespaceManager xnm = new XmlNamespaceManager(doc.NameTable);

                xnm.AddNamespace("s", "uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882");

                xnm.AddNamespace("rs", "urn:schemas-microsoft-com:rowset");
                XmlNode node = doc.SelectSingleNode("//xml/rs:data", xnm);

                XmlNodeReader reader = new XmlNodeReader(node);

                ds.ReadXml(reader);