获取用户列表

获取用户列表的接口说明，参考：

https://developers.weixin.qq.com/doc/offiaccount/User_Management/Getting_a_User_List.html

该接口返回的是用户的OpenID。

例如在命令窗口执行以下代码，可以显示所有用户OpenID：

Dim url As String = "https://api.weixin.qq.com/cgi-bin/user/get?access_token={0}"
Dim hc As New HttpClient(CExp(url, Functions.Execute("GetAccessToken")))
Dim jo As JObject = JObject.Parse(hc.GetData)
If jo("errcode") Is Nothing Then
    Dim sb As New StringBuilder
    For Each jk As JToken  In jo("data")("openid")
       sb.AppendLine(jk)
    Next
    Messagebox.Show(sb.ToString)
Else
    MessageBox.Show(jo.ToString)
End If

提示：如果你的公众号有非常多的用户，不能用MessageBox来显示用户列表，应该保存为一个文本文件。

根据接口说明可知，上述代码最多只能获取前1万个OpenID，如果你的公众号用户数超过1万，需要采用下面的代码才能获取所有OpenID：

Dim url As String = "https://api.weixin.qq.com/cgi-bin/user/get?access_token={0}&next_openid={1}"
Dim hc As New HttpClient(CExp(url, Functions.Execute("GetAccessToken"),""))
Dim sb As New StringBuilder
Dim jo As JObject = JObject.Parse(hc.GetData)
Do
    If jo("errcode") Is Nothing Then
        Dim cnt As Integer = jo("count")
        If cnt > 0 Then
            For Each jk As JToken  In jo("data")("openid")
                sb.AppendLine(jk)
            Next
            hc =  New HttpClient(CExp(url, Functions.Execute("GetAccessToken"),jo("next_openid").Tostring))    
            jo = JObject.Parse(hc.GetData)
        Else
            Exit Do
        End If
    Else
        MessageBox.Show(jo.ToString)
        Exit Do
    End If
Loop
FileSys.WriteAllText("c:\data\openid.txt", sb.ToString, False)