使用PowerShell检索HTML中的文本 [英] Retrieve text in HTML with powershell

问题描述

在这个html代码中：

 < div id =ajaxWarningRegionclass =infoFont>< DIV> 
< span id =ajaxStatusRegion>< / span> 
< form enctype =multipart / form-datamethod =postname =confIPBackupFormaction =/ cgi-bin / utilserv / confIPBackup / w_confIPBackupid =confIPBackupForm> 
< pre> 
从HTTP / PhoneBackup创建IP电话文件的新ZIP 
和HTTPS / PhoneBackup 
< / pre> 
< pre> /tmp/IP_PHONE_BACKUP-2012-Jul-25_15:47:47.zip</pre> 
< pre>报告成功< / pre> 
< pre>< / pre> 
< a href = /tmp/IP_PHONE_BACKUP-2012-Jul-25_15:47:47.zip> 
下载IP电话文件的新ZIP文件
< / a> 
< / div> 
  

我想检索文本 IP_PHONE_BACKUP-2012-Jul-25_15：47 ：47.zip 或只是 IP_PHONE_BACKUP - 和 .zip 之间的日期和时间

我该怎么做？

解决方案

有趣的是，HTML看起来和闻起来就像XML一样，后者由于其良好的行为和有序的结构而更具可编程性。在一个理想的世界中，HTML将是XML的一个子集，但是现实世界中的HTML是着重于XML而不是XML。如果您将问题中的示例提供给任何XML解析器，它将会妨碍各种违规行为。这就是说，只需一行PowerShell就能达到预期的效果。这个返回整个href文本：

  Select-NodeContent $ doc.DocumentNode// a / @ href
  

这个提取所需的子字符串：

  Select-NodeContent $ doc.DocumentNode// a / @ hrefIP_PHONE_BACKUP  - （。*）\.zip
  pre> 
 
 
然而，捕获的开销/设置可以运行那一行代码。您需要：安装     > HtmlAgilityPack  ，使HTML解析看起来就像XML解析一样。 
 
 安装 PowerShell社区扩展 如果你想解析一个实时网页。
   理解XPath 能够构建到目标节点的可导航路径。了解正则表达式以便能够从目标节点中提取子字符串。 
 
 
 $ b 
满足这些要求后，您可以将 HTMLAgilityPath 类型添加到您的环境中，并定义 Select-NodeContent 函数，如下所示。代码的最后一部分显示了如何为上面的单行使用的 $ doc 变量赋值。我展示了如何从文件或网页加载HTML，具体取决于您的需求。
  Set-StrictMode -Version最新
 $ HtmlAgilityPackPath = [System.IO.Path] :: Combine（（Get-Item $ PROFILE）.DirectoryName，bin\HtmlAgilityPack.dll）
 Add-Type -Path $ HtmlAgilityPackPath 
 
函数Select-NodeContent（
 [HtmlAgilityPack.HtmlNode] $ node，
 [string] $ xpath，
 [string] $ regex，
 [Object] $如果给定标准的XPath来检索一个属性，那么给出一个属性（默认=）
 {
 if（$ xpath -match（。*）/ @（\w +）$）{
＃ ，
＃映射到支持的操作以检索属性的文本。 
（$ xpath，$ attribute）= $ matches [1]，$ matches [2] 
 $ resultNode = $ node.SelectSingleNode（$ xpath）
 $ text =？：{$ resultNode } {$ resultNode.Attributes [$ attribute] .Value} {$ default} 
} 
 else {＃检索元素的文本
 $ resultNode = $ node.SelectSingleNode（$ xpath）
 $ text =？：{$ resultNode} {$ resultNode.InnerText} {$ default} 
} 
＃如果给出了一个正则表达式，用它从文本
中提取一个子字符串if（$ regex）{
 if（$ text -match $ regex）{$ text = $ matches [1]} 
 else {$ text = $ default} 
} 
返回$ text 
} 
 
 $ doc = New-Object HtmlAgilityPack.HtmlDocument 
 $ result = $ doc.Load（tmp\temp.html）＃使用它加载文件
＃$ result = $ doc.LoadHtml（（Get-HttpResource $ url））＃使用此PSCX cmdlet加载实时网页
  
 
In this html code :
<div id="ajaxWarningRegion" class="infoFont"></div>
  <span id="ajaxStatusRegion"></span>
  <form enctype="multipart/form-data" method="post" name="confIPBackupForm" action="/cgi-bin/utilserv/confIPBackup/w_confIPBackup" id="confIPBackupForm" >
    <pre>
      Creating a new ZIP of IP Phone files from HTTP/PhoneBackup 
      and HTTPS/PhoneBackup
    </pre>
    <pre> /tmp/IP_PHONE_BACKUP-2012-Jul-25_15:47:47.zip</pre>
    <pre>Reports Success</pre>
    <pre></pre>
    <a href =  /tmp/IP_PHONE_BACKUP-2012-Jul-25_15:47:47.zip>
      Download the new ZIP of IP Phone files
    </a>
  </div>
I want to retrieve the text IP_PHONE_BACKUP-2012-Jul-25_15:47:47.zip or just the date and hour between IP_PHONE_BACKUP- and .zip

How can I do that ?
解决方案
What makes this question so interesting is that HTML looks and smells just like XML, the latter being much more programmably palatable due to its well-behaved and orderly structure. In an ideal world HTML would be a subset of XML, but HTML in the real-world is emphatically not XML. If you feed the example in the question into any XML parser it will balk on a variety of infractions. That being said, the desired result can be achieved with a single line of PowerShell. This one returns the whole text of the href:
Select-NodeContent $doc.DocumentNode "//a/@href"
And this one extracts the desired substring:
Select-NodeContent $doc.DocumentNode "//a/@href" "IP_PHONE_BACKUP-(.*)\.zip"
The catch, however, is in the overhead/setup to be able to run that one line of code. You need to:


Install HtmlAgilityPack to make HTML parsing look just like XML parsing.
Install PowerShell Community Extensions if you want to parse a live web page.
Understand XPath to be able to construct a navigable path to your target node.
Understand regular expressions to be able to extract a substring from your target node.


With those requirements satisfied you can add the HTMLAgilityPath type to your environment and define the Select-NodeContent function, both shown below. The very end of the code shows how you assign a value to the $doc variable used in the above one-liners. I show how to load HTML from a file or from the web, depending on your needs.
Set-StrictMode -Version Latest
$HtmlAgilityPackPath = [System.IO.Path]::Combine((Get-Item $PROFILE).DirectoryName, "bin\HtmlAgilityPack.dll")
Add-Type -Path $HtmlAgilityPackPath

function Select-NodeContent(
    [HtmlAgilityPack.HtmlNode]$node,
    [string] $xpath,
    [string] $regex,
    [Object] $default = "")
{
    if ($xpath -match "(.*)/@(\w+)$") {
        # If standard XPath to retrieve an attribute is given,
        # map to supported operations to retrieve the attribute's text.
        ($xpath, $attribute) = $matches[1], $matches[2]
        $resultNode = $node.SelectSingleNode($xpath)
        $text = ?: { $resultNode } { $resultNode.Attributes[$attribute].Value } { $default }
    }
    else { # retrieve an element's text
        $resultNode = $node.SelectSingleNode($xpath)
        $text = ?: { $resultNode } { $resultNode.InnerText } { $default }
    }
    # If a regex is given, use it to extract a substring from the text
    if ($regex) {
        if ($text -match $regex) { $text = $matches[1] }
        else { $text = $default }
    }
    return $text
}

$doc = New-Object HtmlAgilityPack.HtmlDocument
$result = $doc.Load("tmp\temp.html") # Use this to load a file
#$result = $doc.LoadHtml((Get-HttpResource $url)) # Use this  PSCX cmdlet to load a live web page


                        
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