asp.net 对 xml webconfig的操作

XmlDocument xdc = new XmlDocument();
xdc.Load(Server.MapPath("Web.config"));
XmlNode root = xdc.SelectSingleNode("configuration/appSettings/add");
XmlElement xe = root as XmlElement;
xe.SetAttribute("value","server=.;database=pubs;user id=sa;password=");
xe.InnerText="tesstadd";
xdc.Save(Server.MapPath("Web.config"));
Response.Write(xe.GetAttribute("key"));

Dim xdc As XmlDocument = New XmlDocument
xdc.Load(Request.PhysicalApplicationPath + ("web.xml"))
Dim xn As XmlNode = xdc.SelectSingleNode("root/config/pc")
Dim xe As XmlElement = CType(xn, XmlElement)
xe.GetAttribute("name")
xe.GetAttribute("ip")
xe.GetAttribute("open")
Dim ip As String = xe.GetAttribute("ip")
Dim open As String = xe.GetAttribute("open")
If open = "yes" Then
Else
Response.Redirect(Request.Url.ToString())
End If