Question

在很多情况下，我将IE对象用于测试目的，然后切换到MSXML进行生产。我了解这些响应会产生相同的响应，但是由于某些原因，以下代码会产生两个不同的响应。

Sub testHTTP()
    Dim link As String
    link = "https://www.govtrack.us/congress/members/ralph_abraham/412630"

'THIS IS THE XML SECTION
    Dim xmlHTMLDoc As HTMLDocument
    Dim xmlWeb As msxml2.XMLHTTP60
    Set xmlHTMLDoc = New HTMLDocument
    Set xmlWeb = New msxml2.XMLHTTP60

    xmlWeb.Open "GET", link, False
    xmlWeb.send

    While xmlWeb.readyState <> 4
        DoEvents
    Wend

    Debug.Print " "
    Debug.Print link
    Debug.Print xmlWeb.Status; "XMLHTTP status "; xmlWeb.statusText; " at "; Time

    xmlHTMLDoc.body.innerHTML = xmlWeb.responseText
    Debug.Print "MSXML response finds image tag at position: " & InStr(xmlWeb.responseText, "img")
    Debug.Print "MSXML response getElementsByTagName(img).Length is: " & xmlHTMLDoc.getElementsByTagName("img").Length

'THIS IS THE IE SECTION
    Dim ieHTMLDoc As HTMLDocument
    Dim objIE As Object
    Set ieHTMLDoc = New HTMLDocument
    Set objIE = CreateObject("InternetExplorer.Application")

    With objIE
        .Top = 0
        .Left = 600
        .Width = 800
        .Height = 600
        .Visible = False
    End With

    objIE.navigate (link)
    While objIE.readyState <> 4
        DoEvents
    Wend

    If objIE.readyState = 4 Then
        Set ieHTMLDoc = objIE.document
        Debug.Print "IE response getElementsByTagName(img).Length is: " & ieHTMLDoc.getElementsByTagName("img").Length
    End If

结束子

以下是即时窗口中的结果：

https://www.govtrack.us/congress/members/ralph_abraham/412630
200 XMLHTTP status OK at 7:50:44 PM 
MSXML response finds image tag at position: 8936
MSXML response getElementsByTagName(img).Length is: 0
IE response getElementsByTagName(img).Length is: 10

这是另一个示例，这次尝试查找锚链接：

Sub testHTTP()
    Dim link As String
    link = "https://www.govtrack.us/congress/members/ralph_abraham/412630"

'THIS IS THE XML SECTION
    Dim xmlHTMLDoc As HTMLDocument
    Dim xmlWeb As msxml2.XMLHTTP60
    Set xmlHTMLDoc = New HTMLDocument
    Set xmlWeb = New msxml2.XMLHTTP60

    xmlWeb.Open "GET", link, False
    xmlWeb.send

    While xmlWeb.readyState <> 4
        DoEvents
    Wend

    Debug.Print " "
    Debug.Print link
    Debug.Print xmlWeb.Status; "XMLHTTP status "; xmlWeb.statusText; " at "; Time

    xmlHTMLDoc.body.innerHTML = xmlWeb.responseText
    Debug.Print "MSXML response finds anchor tag at position: " & InStr(xmlWeb.responseText, "<a ")
    Debug.Print "MSXML response getElementsByTagName(<a ).Length is: " & xmlHTMLDoc.getElementsByTagName("a").Length

'THIS IS THE IE SECTION
    Dim ieHTMLDoc As HTMLDocument
    Dim objIE As Object
    Set ieHTMLDoc = New HTMLDocument
    Set objIE = CreateObject("InternetExplorer.Application")

    With objIE
        .Top = 0
        .Left = 600
        .Width = 800
        .Height = 600
        .Visible = False
    End With

    objIE.navigate (link)
    While objIE.readyState <> 4
        DoEvents
    Wend

    If objIE.readyState = 4 Then
        Set ieHTMLDoc = objIE.document
        Debug.Print "IE response getElementsByTagName(<a ).Length is: " & ieHTMLDoc.getElementsByTagName("a").Length
    End If
End Sub

这是直接窗口：

https://www.govtrack.us/congress/members/ralph_abraham/412630
200 XMLHTTP status OK at 12:21:08 PM 
MSXML response finds anchor tag at position: 3774
MSXML response getElementsByTagName(<a ).Length is: 0
IE response getElementsByTagName(<a ).Length is: 131

以下是炸毁代码的方法：

getElementsByClassName("photo")(0).getElementsByTagName("img")(0).src

针对XML请求响应而不是IE响应运行时，这会产生“对象变量或未设置块变量”错误。看起来XML响应中包含所有内容，但没有正确解释为HTMLDocument对象。可能我可以尝试剥离文本文件的某些开头，然后将其重置为HTMLDocument。

我需要知道如何在vba中用IE替代XML或其他http方法。

Answer 1

我认为将XML与IE进行比较就像将苹果与桔子 果汁机进行比较。

Internet Explorer 是Web Browser，旨在简化从远程服务器请求和接收软件包信息的过程，并根据人类设备的需要动态呈现。

XML 是machine-readable markup language，专门用于在Internet上显示文档。这是metalanguage的意思，它可以用来描述或其他语言。

XML定义了文档的逻辑结构以及文档的访问和操作方式。一种组织信息的纯文本方法。

相关：

维基百科：XMLHttpRequest
MSDN：**XMLHttpRequest**
维基百科：Comparison of document markup languages
维基百科：Markdown
MSDN：Beginner's Guide to the XML DOM
堆栈溢出：Why is it called XMLHttpRequest?
Linux基金会：Browser Definition
锡拉丘兹大学：Why HTML is Not a Programming Language

Answer 2

简短的答案可能是MSXML取消了图像（和其他信息），否则这些图像将在使用浏览器时呈现。您正在处理不同的响应文本，尽管它们都是HTML。 MSXML不必将页面访问的所有其他呈现信息通知浏览器。

如果成功，则xmlWeb.responseText返回一个DOMString，其中包含对请求的响应作为文本。

不太理想，但是您可以从responseText中使用regex获得可用的src属性字符串。您可以对其进行调整，使其仅适用于图片扩展名，例如jpeg。

Option Explicit
Public Sub PrintSrcs()
    Dim sResponse As String, html As New HTMLDocument
    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", "https://www.govtrack.us/congress/members/ralph_abraham/412630", False
        .send
        sResponse = StrConv(.responseBody, vbUnicode)
    End With
    sResponse = Mid$(sResponse, InStr(1, sResponse, "<!DOCTYPE "))
    Dim links(), i  As Long
    links = GetLinks(sResponse, "src=""[^""]*")  '(?<=<img src=")[^"]*  '<== no supported?
    For i = LBound(links) To UBound(links)
        Debug.Print links(i)
    Next i
End Sub

Public Function GetLinks(ByVal inputString As String, ByVal sPattern As String) As Variant
    Dim Matches As Object, iMatch As Object, s As String, arrMatches(), i As Long
    With CreateObject("vbscript.regexp")
        .Global = True
        .MultiLine = True
        .IgnoreCase = False
        .Pattern = sPattern
        If .test(inputString) Then
            Set Matches = .Execute(inputString)
            For Each iMatch In Matches
                ReDim Preserve arrMatches(i)
                arrMatches(i) = Replace$(iMatch.Value, "src=""", vbNullString)
                i = i + 1
            Next
        Else
            Debug.Print "Failed"
        End If
    End With
    GetLinks = arrMatches
End Function

为什么VBA MSXML从相同的URL产生的响应与IE Object产生的响应不同？

2 个答案:

相关：