XML 解析。隐藏父节点

Question

所以我有一个解析为 TreeView 列表的 xml 文件，目前我只需要三个节点时大约有四个级别的节点。我想隐藏/删除父节点或顶部节点，因为它没有多大用处。我可以通过编辑 XML 文件本身来做到这一点，但我不允许这样做。代码如下：

private void Form1_Load_1(object sender, EventArgs e)
    {
        // Initialize the controls and the form.
        textBox2.Text = Application.StartupPath + "\\Continental.vsysvar";
    }

    private void button6_Click(object sender, EventArgs e)
    {
        treeView1.BeginUpdate();
        try
        {
            // SECTION 1. Create a DOM Document and load the XML data into it.
            XmlDocument dom = new XmlDocument();
            dom.Load(textBox2.Text);
            // SECTION 2. Initialize the TreeView control.
            try
            {
                // SECTION 2. Initialize the TreeView control.
                //treeView1.Nodes.Clear();
                XmlTreeViewHelper.AddOrMergeNodes(treeView1.Nodes, dom.DocumentElement.ChildNodes, GetTreeNodeName, GetTreeNodeText, FilterNode);
                // SECTION 3. Populate the TreeView with the DOM nodes.
                treeView1.ExpandAll();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                treeView1.EndUpdate();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    static string GetTreeNodeName(XmlNode inXmlNode)
    {
        string text = GetAttributeText(inXmlNode, "name");
        if (string.IsNullOrEmpty(text))
            text = inXmlNode.Name;
        return text;
    }

    static string GetTreeNodeText(XmlNode inXmlNode)
    {
        string text = GetAttributeText(inXmlNode, "name");
        if (string.IsNullOrEmpty(text))
        {
            if (inXmlNode.HasChildNodes)
            {
                text = inXmlNode.Name;
            }
            else
            {
                text = (inXmlNode.OuterXml).Trim();
            }
        }
        return text;
    }

    string filter = "_start"; // Reload when this changes.

    bool FilterNode(XmlNode inXmlNode)
    {
        return FilterNode(inXmlNode, filter);
    }

    bool FilterNode(XmlNode inXmlNode, string nodeNameFilter)
    {
        if (inXmlNode.Name == "namespace" && inXmlNode.ChildNodes.Count == 0 && string.IsNullOrEmpty(GetAttributeText(inXmlNode, "name")))
            return false;
        if (!string.IsNullOrEmpty(nodeNameFilter))
        {
            string text = GetTreeNodeText(inXmlNode);
            if (text.Contains(nodeNameFilter))
                return false;
        }
        return true;
    }
    static string GetAttributeText(XmlNode inXmlNode, string name)
    {   
        XmlAttribute attr = (inXmlNode.Attributes == null ? null : inXmlNode.Attributes[name]);
        return attr == null ? null : attr.Value;
    }

有一个名为 XmlTreeViewHelper 的类，但它很长，所以我决定不在这里包含它（它的主要目的是过滤具有特定字符串集的节点）。让我知道我是否还需要在此处包含它。

无论如何，当我点击按钮时，结果会是这样的：

命名空间
|---A类
|-------对象A1
|-------对象A2
|---B类
|-------对象B1
|-------对象B2

如何隐藏命名空间？我不允许在 xml 文件本身上删除它。该列表应该只显示类别和对象。仅供参考，命名空间在列表中显示为命名空间。以下是 XML 文件的示例。

<?xml version="1.0" encoding="utf-8"?>
<systemvariables version="4">
  <namespace name="" comment="">
    <namespace name="_01_Test_Preparation" comment="">
      <variable anlyzLocal="2" readOnly="false" valueSequence="false" unit="" name="_01_02_Shipping_Status_Check" comment="" bitcount="32" isSigned="true" encoding="65001" type="int" startValue="0" minValue="0" minValuePhys="0" maxValue="4" maxValuePhys="4" />
      <variable anlyzLocal="2" readOnly="false" valueSequence="false" unit="" name="_01_02_Shipping_Status_Check_start" comment="" bitcount="32" isSigned="true" encoding="65001" type="int" startValue="0" minValue="0" minValuePhys="0" maxValue="4" maxValuePhys="4" />
    </namespace>
    <namespace name="_02_Communication" comment="">
      <variable anlyzLocal="2" readOnly="false" valueSequence="false" unit="" name="_02_04_VCAN_StartLoad" comment="" bitcount="32" isSigned="true" encoding="65001" type="int" startValue="0" minValue="0" minValuePhys="0" maxValue="4" maxValuePhys="4" />
      <variable anlyzLocal="2" readOnly="false" valueSequence="false" unit="" name="_02_08_XCP_Restbus_RAM_Monitor" comment="" bitcount="32" isSigned="true" encoding="65001" type="int" startValue="0" minValue="0" minValuePhys="0" maxValue="4" maxValuePhys="4" />
    </namespace>
  </namespace>
</systemvariables>

我在想，如果命名空间的属性名称为空，它将不会包含在列表中。或者至少不会显示。这可能吗？我在网上找到的大多数示例都与删除没有子节点的父节点有关，但在我的例子中，这个父节点有子节点。

Answer 1

最简单的做法是加载DocumentElement 的ChildNodes 的ChildNodes，而不是DocumentElement 的ChildNodes。

首先，将XmlTreeViewHelper.AddOrMergeNodes() 更改为与任何IEnumerable<XmlNode> 一起使用：

public static class XmlNodeHelper
{
    public static IEnumerable<XmlNode> ChildNodes(IEnumerable<XmlNode> xmlNodeList)
    {
        if (xmlNodeList == null)
            yield break;
        foreach (XmlNode node in xmlNodeList)
            foreach (XmlNode childNode in node.ChildNodes)
                yield return childNode;
    }

    public static IEnumerable<TNode> OfType<TNode>(XmlNodeList xmlNodeList) where TNode : XmlNode
    {
        // Convert XmlNodeList which implements non-generic IEnumerable to IEnumerable<XmlNode> by downcasting the nodes
        if (xmlNodeList == null)
            yield break;
        foreach (XmlNode xmlNode in xmlNodeList)
            if (xmlNode is TNode)
                yield return (TNode)xmlNode;
    }
}

public static class XmlTreeViewHelper
{
    public static void AddOrMergeNodes(TreeNodeCollection treeNodeCollection, IEnumerable<XmlNode> xmlNodeList, GetString<XmlNode> getNodeName, GetString<XmlNode> getNodeText, Predicate<XmlNode> filter)
    {
        Dictionary<string, List<TreeNode>> dict = ToNodeDictionary(treeNodeCollection);
        int index = 0;
        foreach (XmlNode inXmlNode in xmlNodeList)
        {
            AddOrMergeNode(treeNodeCollection, inXmlNode, ref index, getNodeName, getNodeText, filter, dict);
        }

        foreach (List<TreeNode> list in dict.Values)
            foreach (TreeNode leftover in list)
            {
                treeNodeCollection.Remove(leftover);
            }
    }

    static bool IsNodeAtIndex(TreeNodeCollection nodes, TreeNode node, int index)
    {
        // Avoid n-squared nodes.IndexOf(node).
        if (index < 0 || index >= nodes.Count)
            return false;
        return nodes[index] == node;
    }

    static void AddOrMergeNode(TreeNodeCollection treeNodeCollection, XmlNode inXmlNode, ref int index, GetString<XmlNode> getNodeName, GetString<XmlNode> getNodeText, Predicate<XmlNode> filter, Dictionary<string, List<TreeNode>> dict)
    {
        if (filter != null && !filter(inXmlNode))
            return;

        string treeName = getNodeName(inXmlNode);
        string treeText = (getNodeText == null ? treeName : getNodeText(inXmlNode));

        bool added = false;

        TreeNode treeNode;
        if (!DictionaryExtensions.TryRemoveFirst(dict, treeName, out treeNode))
        {
            treeNode = new TreeNode();
            treeNode.Name = treeName;
            treeNode.Text = treeText;
            added = true;
            treeNodeCollection.Insert(index, treeNode);
        }
        else
        {
            if (!IsNodeAtIndex(treeNodeCollection, treeNode, index))
            {
                treeNodeCollection.Remove(treeNode);
                treeNodeCollection.Insert(index, treeNode);
            }
        }

        index++;

        if (treeNode.Text != treeText)
            treeNode.Text = treeText;

        if (inXmlNode.HasChildNodes)
            AddOrMergeNodes(treeNode.Nodes, XmlNodeHelper.OfType<XmlNode>(inXmlNode.ChildNodes), getNodeName, getNodeText, filter);
        else
            treeNode.Nodes.Clear();

        if (added)
            treeNode.ExpandAll();
    }

    /// <summary>
    /// Returns a dictionary of tree nodes by node name.
    /// </summary>
    /// <param name="nodes"></param>
    /// <returns></returns>
    static Dictionary<string, List<TreeNode>> ToNodeDictionary(TreeNodeCollection nodes)
    {
        Dictionary<string, List<TreeNode>> dict = new Dictionary<string, List<TreeNode>>();
        foreach (TreeNode node in nodes)
            DictionaryExtensions.Add(dict, node.Name, node);
        return dict;
    }
}

然后，只需加载文档中低一级的节点：

            XmlTreeViewHelper.AddOrMergeNodes(treeView1.Nodes, XmlNodeHelper.ChildNodes(XmlNodeHelper.OfType<XmlNode>(dom.DocumentElement.ChildNodes)), GetTreeNodeName, GetTreeNodeText, FilterNode);