vba WinHttp.WinHttpRequest.5.1 如何设置encoding为null

在用excel做工具，生成微信小程序二维码，数据返回保存为文件，但不能识别为图片。

找了一些答案，如


https://blog.csdn.net/uikoo9/article/details/86088028


需要将request的encoding设置成null,

我代码很简单

Set httpObj = CreateObject("WinHttp.WinHttpRequest.5.1")
httpObj.Open "POST", qr_url, False
httpObj.Send param
If httpObj.status = 200 Then
    fileName = ThisWorkbook.Path & "/" & Format(Date, "yyyymmdd") & ".jpeg"
    FileData = httpObj.ResponseBody
    FileNum = FreeFile
    Open fileName For Binary As #1
    Put #1, , FileData
    Close #FileNum
End If

如何将请求设置成encoding:null？

https://blog.csdn.net/tylm22733367/article/details/52596990