生成临时二维码

临时二维码，是有过期时间的，最长可以设置为在二维码生成后的30天（即2592000秒）后过期。

首先我们创建一个表，用于记录生成的二维码，表名为QRCode，结构如下：



生成临时二维码的代码可以参考：

Dim url As String = "https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token={0}"
Dim hc As New HttpClient(CExp(url,Functions.Execute("GetAccessToken")))
Dim jo As New JObject
jo("expire_seconds") = 86400 '有效时间,单位为秒
jo("action_name") = "QR_SCENE" '类型为临时二维码
jo("action_info") = New JObject
jo("action_info")("scene") = New JObject
jo("action_info")("scene")("scene_id") = 112 '指定此二维码的场景ID
hc.Content = jo.ToString()
jo = JObject.Parse(hc.GetData)
If jo("errcode") Is Nothing Then
    Dim dr As DataRow = DataTables("QRCode").AddNew()
    dr("Ticket") = jo("ticket")
    dr("ExpireDate") = Date.Now .AddSeconds(jo("expire_seconds"))
    dr("Descripttion") = "二维码说明"
    dr.Save()
Else
    MessageBox.Show(jo("errcode"))
End If

二维码生成成功后，会返回一个ticket，通过这个ticket可以获取生成的二维码，格式为：

https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=返回的ticket

假定返回的ticket为：

gQGj8DwAAAAAAAAAAS5odHRwOi8vd2VpeGluLnFxLmNvbS9xLzAyZWo2QjlHY1Y5N1Uxek92b3hvMUoAAgRyzpZYAwSAUQEA

那么可以通过下面的网址，访问生成的ticket,ticket记得进行UrlEncode:

https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=gQGj8DwAAAAAAAAAAS5odHRwOi8vd2VpeGluLnFxLmNvbS9xLzAyZWo2QjlHY1Y5N1Uxek92b3hvMUoAAgRyzpZYAwSAUQEA

如果要将生成的二维码下载到本机，可以参考代码：

Dim ticket As String = "gQGj8DwAAAAAAAAAAS5odHRwOi8vd2VpeGluLnFxLmNvbS9xLzAyZWo2QjlHY1Y5N1Uxek92b3hvMUoAAgRyzpZYAwSAUQEA"
Dim hc As New HttpClient("https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=" & UrlEncode(ticket))
hc.GetFile("c:\data\qrcode.jpg")