如何通过它们的 class 属性解析重复的 HTML 元素？-解网

问：

我正在尝试解析具有基本相同标签的 HTML 文件。

我想得到这个输出：

BTC - 比特币， BEP20（BSC），比特币（Segwit）

ETH - ERC20， BEP20（BSC），多边形，任意币，极光，马蒂塞夫姆

USDT - OMNI，TRC20，ERC20，BEP20（BSC），HECO，POLYGON，FTM， AVAX-C ，ARBITRUM，METISEVM

QASH - ERC20型

下面是 HTML 的示例：

<div data-v-326d86f4="" class="table-box">
   <table data-v-326d86f4="">
      <tr data-v-326d86f4="">
         <td data-v-326d86f4="">BTC</td>
         <td data-v-326d86f4="" class="block-chain">
            <div data-v-326d86f4="" class="chain_box"><span data-v-326d86f4="" class="chain_name">Bitcoin</span> <span data-v-326d86f4=""><i data-v-326d86f4="" class="fa fa-caret-down"></i></span></div>
            <div data-v-326d86f4="" class="select-list"><span data-v-326d86f4="">Bitcoin</span><span data-v-326d86f4="">BEP20(BSC)</span><span data-v-326d86f4="">Bitcoin(SegWit)</span></div>
         </td>
         <td data-v-326d86f4="">0.001</td>
         <td data-v-326d86f4="">0.002</td>
      </tr>
      <tr data-v-326d86f4="">
         <td data-v-326d86f4="">ETH</td>
         <td data-v-326d86f4="" class="block-chain">
            <div data-v-326d86f4="" class="chain_box"><span data-v-326d86f4="" class="chain_name">ERC20</span> <span data-v-326d86f4=""><i data-v-326d86f4="" class="fa fa-caret-down"></i></span></div>
            <div data-v-326d86f4="" class="select-list"><span data-v-326d86f4="">ERC20</span><span data-v-326d86f4="">BEP20(BSC)</span><span data-v-326d86f4="">POLYGON</span><span data-v-326d86f4="">ARBITRUM</span><span data-v-326d86f4="">AURORA</span><span data-v-326d86f4="">METISEVM</span></div>
         </td>
         <td data-v-326d86f4="">0.012</td>
         <td data-v-326d86f4="">0.024</td>
      </tr>
      <tr data-v-326d86f4="">
         <td data-v-326d86f4="">USDT</td>
         <td data-v-326d86f4="" class="block-chain">
            <div data-v-326d86f4="" class="chain_box"><span data-v-326d86f4="" class="chain_name">OMNI</span> <span data-v-326d86f4=""><i data-v-326d86f4="" class="fa fa-caret-down"></i></span></div>
            <div data-v-326d86f4="" class="select-list"><span data-v-326d86f4="">OMNI</span><span data-v-326d86f4="">TRC20</span><span data-v-326d86f4="">ERC20</span><span data-v-326d86f4="">BEP20(BSC)</span><span data-v-326d86f4="">HECO</span><span data-v-326d86f4="">POLYGON</span><span data-v-326d86f4="">FTM</span><span data-v-326d86f4="">AVAX-C</span><span data-v-326d86f4="">ARBITRUM</span><span data-v-326d86f4="">METISEVM</span></div>
         </td>
         <td data-v-326d86f4="">30</td>
         <td data-v-326d86f4="">50</td>
      </tr>
      <tr data-v-326d86f4="">
         <td data-v-326d86f4="">QASH</td>
         <td data-v-326d86f4="" class="block-chain">
            <div data-v-326d86f4="" class="chain_box">
               <span data-v-326d86f4="" class="chain_name">ERC20</span> <!---->
            </div>
            <!---->
         </td>
         <td data-v-326d86f4="">513</td>
         <td data-v-326d86f4="">1026</td>
      </tr>
      <!-- ... -->

我正在使用该库但没有成功：HtmlAgilityPack

Dim arqHtml As String = "C:\Users\Mattia\Desktop\ready.html"
Dim myHtml As HtmlAgilityPack.HtmlDocument = New HtmlAgilityPack.HtmlDocument()
myHtml.Load(arqHtml)
Dim myTable As HtmlAgilityPack.HtmlNode = myHtml.DocumentNode.SelectSingleNode("//table")
Dim myRows As HtmlAgilityPack.HtmlNodeCollection = myTable.SelectNodes("tr")
For Each tmpRow As HtmlAgilityPack.HtmlNode In myRows
    Dim myCells As HtmlAgilityPack.HtmlNodeCollection = tmpRow.SelectNodes("td")
    If myCells IsNot Nothing Then
        Dim myToken As String = myCells(0).InnerText
        Dim mySpans As HtmlAgilityPack.HtmlNodeCollection = myCells(1).SelectNodes("div[contains(@class,'select-list')]/span")
        If mySpans IsNot Nothing Then
            Dim myListBChain As New List(Of String)
            For Each mySpan As HtmlAgilityPack.HtmlNode In mySpans
                RichTextBox1.Text += mySpan.InnerText
            Next
            Dim allItensAsString = String.Join(", ", richtextbox1.text)
        End If
    End If
Next

这将返回以下输出：

比特币BEP20（BSC）比特币（SegWit）ERC20BEP20（BSC）POLYGONARBITRUMAURORAMETISEVMOMNITRC20ERC20BEP20（BSC）HECOPOLYGONFTMAVAX-CARBITRUMMETISEVMEOSBEP20（BSC）ERC20BEP20（BSC）TRC20BEP20（BSC）ZILBEP20（BSC）NEOLEGACYNEON3ERC20POLYGONERC20DAGBEP2BEP20（BSC）FTMAVAX-CERC20BEP20（BSC）ERC20BEP20（BSC）ERC20HECOBEP20（BSC）ERC20HECOERC20POLYGONERC20HECOERC20POLYGONERC20BEP20（BSC）BCHBEP20（BSC）ERC20LOOPPOLYGONBEP20（BSC）FTMAVAX-CMETISEVMERC20TOLERC20METAERC20BEP20（BSC）

如何让它返回我想要的输出？

html .net vb.net html-parsing html-agility-pack

我认为您只需要交换几行：替换为和 .但是，这不会正确地将 for 多个 s 的值（使用换行符或）连接在一起。RichTextBox1.Text += mySpan.InnerTextmyListBChain.Add(mySpan.InnerText)Dim allItensAsString = String.Join(", ", myListBChain)RichTextBox1.Text += String.Join(", ", myListBChain),RichTextBox1.TexttmpRow

0赞 2/6/2022

刚刚尝试了你建议我的，但输出仍然不清楚，就像

Bitcoin, BEP20(BSC), Bitcoin(SegWit)ERC20, BEP20(BSC), POLYGON, ARBITRUM, AURORA, METISEVMOMNI, TRC20, ERC20, BEP20(BSC), HECO, POLYGON, FTM, AVAX-C, ARBITRUM, METISEVMEOS, BEP20(BSC)ERC20, BEP20(BSC)TRC20, BEP20(BSC)ZIL, BEP20(BSC)NEOLEGACY, NEON3ERC20, POLYGONERC20

答：

0赞 Lance U. Matthews 2/6/2022 #1

将我对原始问题的评论纳入示例的最后一个......<tr>

<tr data-v-326d86f4="">
    <td data-v-326d86f4="">QASH</td>
    <td data-v-326d86f4="" class="block-chain">
    <div data-v-326d86f4="" class="chain_box">
        <span data-v-326d86f4="" class="chain_name">ERC20</span> <!---->
    </div>
    <!---->
    </td>
    <td data-v-326d86f4="">513</td>
    <td data-v-326d86f4="">1026</td>
</tr>

...第二个不包含，所以......<td><div class="select-list" ... >

myCells(1).SelectNodes("div[contains(@class,'select-list')]/span")

...返回，因此 .NothingNullReferenceException

至于构建你想要的输出，首先你需要测试这样的元素是否存在......<div class="select-list" ... >

If mySpans Is Nothing Then

如果没有，则保存元素的内容...<div class="chain_box" ... ><span class="chain_name ... >

Dim chainTextNode As HtmlAgilityPack.HtmlNode = myCells(1).SelectSingleNode(
    "div[contains(@class, 'chain_box')]/span[contains(@class, 'chain_name')]"
)

chainText = If(chainTextNode Is Nothing OrElse String.IsNullOrWhiteSpace(chainTextNode.InnerText), "(unknown)", chainTextNode.InnerText)

我添加了一些额外的处理，以防该元素不存在或没有值。

如果有一个元素，则保存其子元素的值，用逗号分隔...<div class="select-list" ... ><span ... >

chainText = String.Join(", ", mySpans.Select(Function(span) span.InnerText))
' Alternative: chainText = String.Join(", ", From span In mySpans Select span.InnerText)

最后，构建一个新行并将其附加到文本框中...

RichTextBox1.Text &= $"{myToken} - {chainText}{Environment.NewLine}"

完整的代码如下所示...

Dim arqHtml As String = "C:\Users\Mattia\Desktop\ready.html"
Dim myHtml As HtmlAgilityPack.HtmlDocument = New HtmlAgilityPack.HtmlDocument()
myHtml.Load(arqHtml)
Dim myTable As HtmlAgilityPack.HtmlNode = myHtml.DocumentNode.SelectSingleNode("//table")

Dim myRows As HtmlAgilityPack.HtmlNodeCollection = myTable.SelectNodes("tr")
For Each tmpRow As HtmlAgilityPack.HtmlNode In myRows
    Dim myCells As HtmlAgilityPack.HtmlNodeCollection = tmpRow.SelectNodes("td")
    If myCells IsNot Nothing Then
        Dim myToken As String = myCells(0).InnerText
        Dim mySpans As HtmlAgilityPack.HtmlNodeCollection = myCells(1).SelectNodes("div[contains(@class,'select-list')]/span")
        Dim chainText As String

        If mySpans Is Nothing Then
            Dim chainTextNode As HtmlAgilityPack.HtmlNode = myCells(1).SelectSingleNode(
                "div[contains(@class, 'chain_box')]/span[contains(@class, 'chain_name')]"
            )

            chainText = If(chainTextNode Is Nothing OrElse String.IsNullOrWhiteSpace(chainTextNode.InnerText), "(unknown)", chainTextNode.InnerText)
        Else
            chainText = String.Join(", ", mySpans.Select(Function(span) span.InnerText))
            ' Alternative: chainText = String.Join(", ", From span In mySpans Select span.InnerText)
        End If

        RichTextBox1.Text &= $"{myToken} - {chainText}{Environment.NewLine}"
    End If
Next

如果您有一个非常大的输入 HTML 文件，您可以考虑...

将每次迭代的行附加到 StringBuilder... ...然后在循环后设置一次......

outputBuilder.Append($"{myToken} - {chainText}{Environment.NewLine}")

RichTextBox1.Text

RichTextBox1.Text = outputBuilder.ToString()

（假设 WinForms）在循环之前调用 RichTextBox1.SuspendLayout（），在循环之后调用 RichTextBox1.ResumeLayout（）

...但是，为了提高性能，使用其中一种或两种方法意味着在完全处理 HTML 之前不会显示任何输出。RichTextBox1

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下一个：获取页面上的所有链接 - HtmlAgilityPack

如何通过它们的 class 属性解析重复的 HTML 元素？

How can I parse repeated HTML elements by their class attribute?

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