基于 Tag 选择 XmlNode 的子节点

Question

我正在尝试解析这个 XML 文档：

<MPD>
  <Period duration="PT0H3M1.63S" start="PT0S">
    <AdaptationSet>
      <ContentComponent contentType="video" id="1" />
      <Representation bandwidth="4190760" codecs="avc1.640028" height="1080" id="1" mimeType="video/mp4" width="1920">
        <BaseURL>car-20120827-89.mp4</BaseURL>
      </Representation>
      <Representation bandwidth="2073921" codecs="avc1.4d401f" height="720" id="2" mimeType="video/mp4" width="1280">
        <BaseURL>car-20120827-88.mp4</BaseURL>
      </Representation>
    </AdaptationSet>
    <AdaptationSet>
      <ContentComponent contentType="audio" id="2" />
      <Representation bandwidth="127236" codecs="mp4a.40.2" id="6" mimeType="audio/mp4" numChannels="2" sampleRate="44100">
        <BaseURL>car-20120827-8c.mp4</BaseURL>
      </Representation>
      <Representation bandwidth="255236" codecs="mp4a.40.2" id="7" mimeType="audio/mp4" numChannels="2" sampleRate="44100">
        <BaseURL>car-20120827-8d.mp4</BaseURL>
      </Representation>
    </AdaptationSet>
  </Period>
</MPD>

使用此 C# 代码：

var rootDoc = new XmlDocument();
rootDoc.LoadXml(xmlString); // the one from above

var adaptationSets = rootDoc.GetElementsByTagName("AdaptationSet");

if (adaptationSets.Count > 0)
    foreach (XmlNode adaptionSet in adaptationSets) // Loop through AdaptionSets
    {
        // Get the one Node in this AdaptionSet with the ContentComponent-Tag
        var contentComponent = adaptionSet.SelectSingleNode("ContentComponent");

        if (contentComponent != null)
        {
            // parse attributes
        }

        // Get All Nodes in this AdaptionSet with the Representation-Tag
        var representations = adaptionSet.SelectNodes("Representation");

        if(representations?.Count > 0)
            foreach (XmlNode representation in representations)
            {
                // parse attributes of XmlNode
            }
    }

除了 XPath 查询之外，它都可以工作。我尝试了很多带有前导“/”、“//”、“./”且没有任何前导字符的变体，但它就是行不通。我究竟做错了什么？我没有定期使用 XPath，除了我提到的主要字符外，我找不到任何东西。因为我在这个网站上的很多其他答案中都看到了它，所以我觉得我应该提一下，我正在明确寻找可以帮助我解决这个问题的 XPath，而不是一些 Linq 变体或完全不同的方法。

非常感谢任何帮助。提前致谢！

Answer 1

我认为这可以解决您的问题：

var rootDoc = new XmlDocument();
rootDoc.LoadXml(xmlString); // the one from above

var adaptationSets = rootDoc.SelectNodes("//AdaptationSet");

if (adaptationSets.Count > 0)
    foreach (XmlNode adaptionSet in adaptationSets) // Loop through AdaptionSets
    {
        // Get the one Node in this AdaptionSet with the ContentComponent-Tag
        var contentComponent = adaptionSet.SelectSingleNode("./ContentComponent");

        if (contentComponent != null)
        {
            // parse attributes
        }

        // Get All Nodes in this AdaptionSet with the Representation-Tag
        var representations = adaptionSet.SelectNodes("./Representation");

        if (representations?.Count > 0)
            foreach (XmlNode representation in representations)
            {
                // parse attributes of XmlNode
            }
    }

Answer 2

尝试使用 xml linq ：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;

namespace ConsoleApplication1
{
    class Program
    {
        const string FILENAME = @"c:\temp\test.xml";
        static void Main(string[] args)
        {
            XDocument doc = XDocument.Load(FILENAME);
            XElement period = doc.Descendants("Period").FirstOrDefault();

            MPD mpd = new MPD();
            mpd.duration = (string)period.Attribute("duration");
            mpd.start = (string)period.Attribute("start");
            mpd.adaptions = period.Elements("AdaptationSet").Select(x => new Adaption() {
                contentType = (string)x.Element("ContentComponent").Attribute("contentType"),
                id = (int)x.Element("ContentComponent").Attribute("id"),
                representations = x.Elements("Representation").Select(y => new Representation() {
                    bandwidth = (int)y.Attribute("bandwidth"),
                    codecs = (string)y.Attribute("codecs"),
                    height = (int?)y.Attribute("height"),
                    id = (int)y.Attribute("id"),
                    mimeType = (string)y.Attribute("mimeType"),
                    width = (int?)y.Attribute("width"),
                    baseURL = (string)y.Descendants("BaseURL").FirstOrDefault()
                }).ToList()
            }).ToList();

        }
    }
    public class MPD
    {
        public string duration { get; set; }
        public string start { get; set; }
        public List<Adaption> adaptions { get; set; }
    }
    public class Adaption
    {
        public string contentType { get; set; }
        public int id { get; set; }
        public List<Representation> representations { get; set; }
    }
    public class Representation
    {
        public int bandwidth { get; set; }
        public string codecs { get; set; }
        public int? height { get; set; }
        public int id { get; set; }
        public string mimeType { get; set; }
        public int? width { get; set; }
        public string baseURL { get; set; }
    }

}