原则与操作XML文件相同。

    Private Sub SaveSetting(ByVal strKeyName As String, ByVal strKeyValue As String, ByVal strWhich As String)

        '创建XML文档实例
        Dim XMLWebSetting As System.Xml.XmlDocument = New System.Xml.XmlDocument
        '打开XML文档
        XMLWebSetting.Load(System.Web.HttpContext.Current.Server.MapPath("~/" + strWhich + ""))

        '查找节点所在位置
        Dim XmlNodeList As System.Xml.XmlNodeList = XMLWebSetting.SelectSingleNode("//appSettings").ChildNodes
        Dim xn As System.Xml.XmlNode
        Dim xe As System.Xml.XmlElement
        Try
            For Each xn In XmlNodeList
                xe = CType(xn, System.Xml.XmlElement)
                If xe.Attributes("key").InnerText = strKeyName Then
                    xe.Attributes("value").InnerText = strKeyValue
                    XMLWebSetting.Save(System.Web.HttpContext.Current.Server.MapPath("~/" + strWhich + ""))
                    Exit For
                End If
            Next
        Catch
        End Try
    End Sub