这里是使用 XElement 的简单示例:

Here is a simple example using XElement:

            string TestXml = @"<root>
    <one>first_one</one>
    <two>second_one</two>
    <tree>third_one</tree>
    <four>fourth_one</four>
    <five>fifth_one</five>
    <six>sixth_one</six>
</root>";

            XElement x = XElement.Parse(TestXml);
            var one = x.Element("one");
            one.Value = "CHANGED ONE";
            x.Element("two").Remove();

            foreach (var item in x.Elements())
            {
                Debug.Print(item.ToString());
            }

如果您更喜欢使用 XDocument ，这没什么不同，您将必须记住使用根，请参见此处的说明: ^ ]
但是正如MSDN文档所述:

If you prefer using XDocument, this is not much different, you will have to remember to use the root, see explanation here: Querying an XDocument vs. Querying an XElement (C#) | Microsoft Docs[^]
But as the MSDN documentation states:

在许多情况下，您的应用程序将不需要您创建文档.通过使用XElement类，可以创建XML树，向其添加其他XML树，修改XML树并保存.

In many cases, your application will not require that you create a document. By using the XElement class, you can create an XML tree, add other XML trees to it, modify the XML tree, and save it.

^ ]

请注意，使用.NET 3.0或更低版本时，您只需要 XmlDocument .

XDocument Class Overview (C#) | Microsoft Docs[^]

Note that you only need XmlDocument when using .NET version 3.0 or lower.

请参考MSDN文档:XmlDocument类(System.Xml)| Microsoft文档 [ ^ ]，尤其是 ^ ]和Edit nodes.
您可能对使用XPath导航选择节点 [

Please, refer MSDN documentation: XmlDocument Class (System.Xml) | Microsoft Docs[^], especially Find nodes[^] and Edit nodes.
You might be interested in Select Nodes Using XPath Navigation[^]


According to the OP requirements (posted in solution 3):

我想保持xml文件的原样
1.我唯一需要的是创建一个类，如读取一，二，树或所有值元素
2.一类更新一，二，树或所有值元素

I Want to keep the xml file like it is
1. The only think I need is to create class like read one, two, tree or all values elements
2. one class to update one, two, tree or all values elements

我建议将您的xml结构更改为此:

I''d recommend to change your xml structure to this one:

<MyItems>
    <MyItem id = "first">first one</Item>
    <MyItem id = "second">first one</Item>
    <MyItem id = "third">first one</Item>
    <MyItem id = "fourth">first one</Item>
    <!-- and so on -->
</MyItems>

表示单个项目的类可能类似于:

A class representing single item this may look like:

public class MyItem
{
	public string id = "first";
	public string text = "first_one";  
}

最后，您需要一个MyItem的集合.

有关更多详细信息，请阅读我的提示:自定义的完整示例类集合序列化和反序列化 [ ^ ].没错，它是用Vb.net编写的，但是您必须处理它，因为Vb.net与C#非常相似.

Finally, you need a collection of MyItem.

For further details, please read my tip: A Complete Sample of Custom Class Collection Serialization and Deserialization[^]. True, it''s written in Vb.net, but you have to handle it, because Vb.net is pretty similar to C#.