XMLHTTP.send request brings back “Nothing”

问题

I have a spreadsheet that has hundreds of links that point to a server (with authentication) that can be accessed via the web. I've been searching for a solution to a Link Checker in a spreadsheet that would tell me which links are broken and which are ok. By broken I mean that the website does not get called up at all.

There are various solutions I have found around the web, none of which work for me. I'm boggled by this...

One example that I've tried to use and figure out is re-posted below.

As I've stepped through the code, I have come to realize that the oHTTP.send request brings back "Nothing". It does so for all links in the spreadsheet, regardless of whether the link works, or not.

Public Function CheckHyperlink(ByVal strUrl As String) As Boolean

    Dim oHttp As New MSXML2.XMLHTTP30

    On Error GoTo ErrorHandler
    oHttp.Open "HEAD", strUrl, False
    oHttp.send

    If Not oHttp.Status = 200 Then CheckHyperlink = False Else CheckHyperlink = True

    Exit Function

ErrorHandler:
    CheckHyperlink = False
End Function

Any suggestions as to what might be wrong, or right, is highly appreciated!

回答1:

A couple of possible causes..

Do you mean oHttp.Open "GET", strUrl, False instead of oHttp.Open "HEAD", strUrl, False ?
Perhaps MSXML2.XMLHTTP30 is not available? You can declare an instance of MSXML2.XMLHTTPX as either early bound or late bound which may impact which version you want to use vs what is available (example http://word.mvps.org/FAQs/InterDev/EarlyvsLateBinding.htm)

Option Explicit

'Dim oHTTPEB As New XMLHTTP30 'For early binding enable reference Microsoft XML, v3.0
Dim oHTTPEB As New XMLHTTP60 'For early binding enable reference Microsoft XML, v6.0

Sub Test()
Dim chk1 As Boolean
Dim chk2 As Boolean

 chk1 = CheckHyperlinkLB("http://stackoverflow.com/questions/11647297/xmlhttp-send-request-brings-back-nothing")

 chk2 = CheckHyperlinkEB("http://stackoverflow.com/questions/11647297/xmlhttp-send-request-brings-back-nothing")

End Sub

Public Function CheckHyperlinkLB(ByVal strUrl As String) As Boolean
Dim oHTTPLB As Object

'late bound declaration of MSXML2.XMLHTTP30
    Set oHTTPLB = CreateObject("Msxml2.XMLHTTP.3.0")

    On Error GoTo ErrorHandler
    oHTTPLB.Open "GET", strUrl, False
    oHTTPLB.send

    If Not oHTTPLB.Status = 200 Then CheckHyperlinkLB = False Else CheckHyperlinkLB = True

    Set oHTTPLB = Nothing
    Exit Function

ErrorHandler:
    Set oHTTPLB = Nothing
    CheckHyperlinkLB = False
End Function


Public Function CheckHyperlinkEB(ByVal strUrl As String) As Boolean
'early bound declaration of MSXML2.XMLHTTP60

    On Error GoTo ErrorHandler
    oHTTPEB.Open "GET", strUrl, False
    oHTTPEB.send

    If Not oHTTPEB.Status = 200 Then CheckHyperlinkEB = False Else CheckHyperlinkEB = True

    Set oHTTPEB = Nothing
    Exit Function

ErrorHandler:
    Set oHTTPEB = Nothing
    CheckHyperlinkEB = False
End Function

EDIT:

I tested the OP's link by opening in a browser which I've now discovered redirects to the login page instead so it's a different link I was testing. It's probably failing because the oHttp object has not been set to allow redirects. I know it's possible to set redirects for WinHttp.WinHttpRequest.5.1 using the code below. I would need to investigate if this also works for MSXML2.XMLHTTP30 though.

Option Explicit

Sub Test()
Dim chk1 As Boolean

 chk1 = CheckHyperlink("http://portal.emilfrey.ch/portal/page/portal/toyota/30_after_sales/20_ersatzteile%20und%20zubeh%C3%B6r/10_zubeh%C3%B6r/10_produktbezogene%20informationen/10_aussen/10_felgen/10_asa-pr%C3%BCfberichte/iq/tab1357333/iq%20016660.pdf")

End Sub


Public Function CheckHyperlink(ByVal strUrl As String) As Boolean
Dim GetHeader As String

    Const WinHttpRequestOption_EnableRedirects = 6
    Dim oHttp As Object

    Set oHttp = CreateObject("WinHttp.WinHttpRequest.5.1")

    On Error GoTo ErrorHandler
    oHttp.Option(WinHttpRequestOption_EnableRedirects) = True
    oHttp.Open "HEAD", strUrl, False
    oHttp.send

    If Not oHttp.Status = 200 Then
        CheckHyperlink = False
    Else
        GetHeader = oHttp.getAllResponseHeaders()
        CheckHyperlink = True

    End If

    Exit Function

ErrorHandler:
    CheckHyperlink = False
End Function

EDIT2:

MSXML2.XMLHTTP does allow redirects (although I believe MSXML2.ServerXMLHTTP doesn't). The redirects are allowed/disallowed depending upon whether the redirect is cross-domain, cross-port etc (see details here http://msdn.microsoft.com/en-us/library/ms537505(v=vs.85).aspx)

Since the redirect to the login page is cross-domain then IE zone policy is implemented. Open IE/Tools/Internet Options/Security/Custom Level and change 'Access data sources across domains' to ENABLED

The original OP's code will now redirect properly.

来源：https://stackoverflow.com/questions/11647297/xmlhttp-send-request-brings-back-nothing

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