使用 VB.Net XmlDocument.SelectNodes 方法读取 XML 文件产生零计数

Question

我是编码和 XML 文件的新手，我正在尝试从 XML 文件中读取详细信息。这是我正在测试的示例文件：

<?xml version="1.0" standalone="yes"?>
<mailmanager xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <locations>
    <store id="c35e549f-ffb8-4828-8290-d66c2f9b735f">
      <type>msg</type>
      <description>Volkswagen</description>
      <folder>G:\Volkswagen</folder>
    </store>
    <store id="814e7584-9f99-40a6-8520-3f5d467ea8d9">
      <type>msg</type>
      <description>Nissan</description>
      <folder>G:\Nissan</folder>
    </store>
    <store id="51d60458-01ac-421d-8fb8-3663f5963fbf">
      <type>msg</type>
      <description>Ford</description>
      <folder>G:\Ford</folder>
    </store>
    <store id="581d96c6-ea30-4301-b83b-d80473d18399">
      <type>msg</type>
      <description>Toyota</description>
      <folder>G:\Toyota</folder>
    </store>
    <store id="888eaace-9486-41db-a4ad-a21d570b0f35">
      <type>msg</type>
      <description>Tesla</description>
      <folder>G:\Tesla</folder>
    </store>
    <store id="44a6eaea-979c-4340-8a1d-1142507c42a0">
      <type>msg</type>
      <description>Fiat</description>
      <folder>G:\Fiat</folder>
    </store>
  </locations>
</mailmanager>

我发现虽然我可以在调试中检查 m_xmld（使用 Visual Studio）并且可以看到它显示了 DocumentElement名称为“mailmanager”，这似乎是正确的，对象 m_nodelist 的计数为零，因此跳过 For Each 循环中的代码。知道我哪里出错了吗？

Private Sub LoadXMLToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles LoadXMLToolStripMenuItem.Click
    Dim GUID As String
    Dim sType As String
    Dim sDescription As String
    Dim sPath As String
    Dim arr As String() = New String(3) {}
    Dim arListItem As ListViewItem

    Dim m_xmld As XmlDocument
    Dim m_nodelist As XmlNodeList
    Dim m_node As XmlNode

    ''Create the columns for the listview
    ListView1.Columns.Add("GUID", 600)
    ListView1.Columns.Add("Description", 100)
    ListView1.Columns.Add("Path", 70)
    ListView1.View = System.Windows.Forms.View.Details
    Application.DoEvents()

    m_xmld = New XmlDocument
    m_xmld.Load("c:\temp\testing2.xml")

    'Get the list of name nodes 
    m_nodelist = m_xmld.SelectNodes("/locations/store")

    'Loop through the nodes
    For Each m_node In m_nodelist
        'Get GUID
        GUID = m_node.Attributes.GetNamedItem("id").Value
        'Get the Description Attribute Value
        sDescription = m_node.ChildNodes.Item(1).InnerText
        'Get the Path Element Value
        sPath = m_node.ChildNodes.Item(2).InnerText


        ''Add a row to the listview
        arr(0) = sType
        arr(1) = sDescription
        arr(2) = sPath
        arListItem = New ListViewItem(arr)
        ListView1.Items.Add(arListItem)
        Application.DoEvents()
    Next

End Sub

Answer 1

我建议使用 XDocument 而不是 XmlDocument。您可以在此处找到文档：https://docs.microsoft.com/en-us/dotnet/api/system.xml.linq.xdocument

然后您将通过调用 Descendants 方法获得各种 <store> 元素：https://docs.microsoft.com/en-us/dotnet/api/system.xml.linq.xcontainer.descendants

看看这个例子：

Dim m_xmld = XDocument.Load("testing2.xml")
Dim m_nodelist = m_xmld.Descendants("store")

For Each m_node In m_nodelist
    ListView1.Items.Add(New ListViewItem({
        m_node.Attribute("id").Value,
        m_node.Element("description").Value,
        m_node.Element("folder").Value
    }))
Next

示例：https://dotnetfiddle.net/Kd8gQd

使用 VB.Net XmlDocument.SelectNodes 方法读取 XML 文件产生零计数

Reading XML file with VB.Net XmlDocument.SelectNodes method yields count of zero

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