接收二维码扫描事件

用户扫描带场景ID的二维码，会向Foxtable端的HTTP服务推送事件，事件推送分两种情况：

• 用户已经关注时，推送的是扫描SCAN，事件参数EventKey为二维码的情景ID，事件参数Ticket为二维码的Ticket。
• 用户未关注时，推送的是关注事件subscribe，和平常的关注事件不同，此时subscribe事件也有包括EventKey和Ticket参数，需要注意的是subscribe事件的EventKey由字符串"qrscene_"和二维码的情景ID组成。

接收处理二维码扫描事件，可以参考以下HttpRequest事件代码：

Select Case e.path
    Case "wefox"
        If e.Request.HttpMethod.ToUpper = "GET"
            If Functions.Execute("VerifySignature",e) Then
                e.WriteString(e.GetValues("echostr"))
            End If
        ElseIf e.Request.HttpMethod.ToUpper = "Post"
            Dim xo As Foxtable.XObject = Foxtable.XObject.Parse(e.PlainText)
            Dim st As New Date(1970,1,1,8,0,0)
            Select Case xo("MsgType")
                Case "text","image"
                    '保存和回复文本和图片消息的代码
                Case "event"
                    Select Case xo("Event")
                        Case "subscribe" '关注事件
                            '处理用户关注事件的代码
                            Dim eKey As String = xo("EventKey")
                            If eKey  IsNot Nothing AndAlso eKey.StartsWith("qrscene_")Then '判断是否是通过扫描二维码关注
                                Dim openid As String = xo("FromUserName") '获取用户OpenID
                                Dim ticket As String = xo("Ticket") '获取二维码的ticket
                                Dim sceneid As String = eKey.SubString(8)  '获取二维码的情景ID,排除前缀qrscene_
                                '被动回复消息
                                Dim so As New Foxtable.XObject()
                                so("ToUserName") = xo("FromUserName")
                                so("FromUserName") = xo("ToUserName")
                                so("CreateTime") = (Date.Now - st).TotalSeconds()
                                so("MsgType") = "text"
                                so("Content") = "您好,谢谢关注,您扫描的二维码的情景ID为" & sceneid
                                e.WriteString(so.ToXML)
                            End If
                        Case "unsubscribe" '取消关注事件
                            '处理用户取消关注事件的代码'
                        Case "LOCATION" '上报地理位置事件
                            '处理用户上报地理位置的代码
                        Case "TEMPLATESENDJOBFINISH"
                            '处理模板消息发送事件的代码
                        Case "SCAN"
                            Dim openid As String = xo("FromUserName") '获取用户OpenID
                            Dim ticket As String = xo("Ticket") '获取二维码的ticket
                            Dim sceneid As String = xo("EventKey") '获取二维码的情景ID
                            '被动回复消息
                            Dim so As New Foxtable.XObject()
                            so("ToUserName") = xo("FromUserName")
                            so("FromUserName") = xo("ToUserName")
                            so("CreateTime") = (Date.Now - st).TotalSeconds()
                            so("MsgType") = "text"
                            so("Content") = "您好,您扫描的二维码的情景ID为" & sceneid
                            e.WriteString(so.ToXML)
                    End Select
            End Select
        End If
End Select

为避免代码冗余，也为了精简HttpRequest事件代码，建议将相关代码做成自定义函数。