How do I get the value from a specific node in an XML file?

问题

From this XML code:

<?xml version="1.0" encoding="utf-8"?>
<Tabel>
  <Member>
    <Naam>Cruciatum</Naam>
    <Kills>1000</Kills>
    <Deaths>10</Deaths>
    <KD>100</KD>
  </Member>
  <Member>
    <Naam>Ghostbullet93</Naam>
    <Kills>10</Kills>
    <Deaths>1</Deaths>
    <KD>10</KD>
  </Member>
</Tabel>

How can I get (for example) the 10 next to <Kills> ?

I've tried multiple things without any success. One of the ideas I had was using this code:

Dim doc = XDocument.Load("C:\members.xml")
        Dim members = From m In doc.Element("Tabel").Elements("Member")
                      Select naam = m.Element("Naam").Value
        For Each member In members
            lstmembers.Items.Add(member)
        Next

But I can't figure out how to edit that snippet to work with what I need it to do now.

(The above code works perfectly for where it's used.)

回答1:

You can also use XPath to read the element's value:

Dim doc As XmlDocument = New XmlDocument()
doc.Load("C:\members.xml")
Dim kills As String = doc.SelectNode("Tabel/Member[Naam='Ghostbullet93']/Kills").InnerText

If, however, you intend to load and use all the data, it would be far easier to use serialization. To do that, you first need to create classes that mimic the XML structure (for simplicity sake I'll just use public string fields, but it would be better to use properties):

Public Class Member
    Public Naam As String
    Public Kills As Integer
    Public Deaths As Integer
    Public KD As Integer
End Class

Public Class Tabel
    <XmlElement("Member")> _
    Public Members As List(Of Member)
End Class

Then deserialize the XML like this:

Dim serializer As XmlSerializer = New XmlSerializer(GetType(Tabel))
Dim tabel As Tabel = CType(serializer.Deserialize(File.OpenRead("C:\members.xml")), Tabel)
For Each member As Member in tabel
    Dim kills As Integer = member.Kills
Next

回答2:

XPath or XmlDeserialization a recommended by Steve are excellent options, but for a pure LINQ solution, you just need to add an appropriate Where clause to your query.

Dim doc = XDocument.Load("C:\members.xml")
Dim members = From m In doc.Element("Tabel").Elements("Member")
              Where m.Element("Naam").Value = "Ghostbullet93"
              Select kills = m.Element("Kills").Value

members will still be an IEnumerable<String> in this example, so if you only have 1 object, you need to do something like:

Dim member = members.First()  // will throw exception if collection is empty

Dim member = members.Single()  // will throw exception if collection is empty or has 2 or more elements

(My vb.NET is extremely rusty, so please forgive any syntax errors).

来源：https://stackoverflow.com/questions/10725820/how-do-i-get-the-value-from-a-specific-node-in-an-xml-file

标签

xml

vb.net

linq

xpath

xml-serialization