修改web.config

    Public Shared Sub SaveSetting(ByVal strKeyName As String, ByVal strKeyValue As String, ByVal strWhich As String)
        Dim XMLWebSetting As New System.Xml.XmlDocument

        XMLWebSetting.Load(System.Web.HttpContext.Current.Server.MapPath(("~/" + strWhich)))

        Dim XmlNodeList As System.Xml.XmlNodeList = XMLWebSetting.SelectSingleNode("//appSettings").ChildNodes
        Try
            Dim xn As System.Xml.XmlNode
            For Each xn In XmlNodeList
                Dim xe As System.Xml.XmlElement = 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 xn
        Catch Ex As System.Exception
            Throw Ex
        End Try
    End Sub