VB 如何获取这个链接上的文件大小

Private Sub Command1_Click()
url = "http://www.hairunqianyi.com/feature/nsmzjnyy.mp3"
If Trim(url) <> "" Then
Set xml = CreateObject("MSXML2.XMLHTTP")
xml.open "GET", url, False
xml.send
header = xml.GetAllResponseHeaders

MsgBox header
Set xml = Nothing
End If

End Sub