xml文件：

<?xml version="1.0" encoding="gb2312"?>

<bookstore>

  <book ISBN="2-3631-4">

    <title>Oberon's   Legacy</title>

    <author>Corets,   Eva</author>

    <price>5.95</price>

  </book>

</bookstore>

code：

Imports System.Xml

Public Class Form1

    Dim xmlDoc As New XmlDocument()

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        '往<bookstore>节点中插入一个<book>节点：

        xmlDoc.Load("bookstore.xml")

        Dim root As XmlNode = xmlDoc.SelectSingleNode("bookstore") '查找<bookstore>

        Dim xe1 As XmlElement = xmlDoc.CreateElement("book") '创建一个<book>节点

        xe1.SetAttribute("genre", "李赞红") '设置该节点genre属性

        xe1.SetAttribute("ISBN", "2-3631-4") '设置该节点ISBN属性

        Dim xesub1 As XmlElement = xmlDoc.CreateElement("title")

        xesub1.InnerText = "CS从入门到精通" '设置文本节点

        xe1.AppendChild(xesub1) '添加到<book>节点中

        Dim xesub2 As XmlElement = xmlDoc.CreateElement("author")

        xesub2.InnerText = "候捷"

        xe1.AppendChild(xesub2)

        Dim xesub3 As XmlElement = xmlDoc.CreateElement("price")

        xesub3.InnerText = "58.3"

        xe1.AppendChild(xesub3)

        root.AppendChild(xe1) '添加到<bookstore>节点中

        xmlDoc.Save("bookstore.xml")

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Dim nodeList As XmlNodeList = xmlDoc.SelectSingleNode("bookstore").ChildNodes '获取bookstore节点的所有子节点

        Dim xn As XmlNode

        For Each xn In nodeList '遍历所有子节点

            Dim xe As XmlElement = CType(xn, XmlElement) '将子节点类型转换为XmlElement类型

            If xe.GetAttribute("genre") = "李赞红" Then '如果genre属性值为“李赞红”

                xe.SetAttribute("genre", "update李赞红") '则修改该属性为“update李赞红”

                Dim nls As XmlNodeList = xe.ChildNodes '继续获取xe子节点的所有子节点

                Dim xn1 As XmlNode

                For Each xn1 In nls '遍历

                    Dim xe2 As XmlElement = CType(xn1, XmlElement) '转换类型

                    If xe2.Name = "author" Then '如果找到

                        xe2.InnerText = "亚胜" '则修改

                        Exit For '找到退出来就可以了

                    End If

                Next xn1

                Exit For

            End If

        Next xn

        xmlDoc.Save("bookstore.xml") '保存。

    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

        Dim xnl As XmlNodeList = xmlDoc.SelectSingleNode("bookstore").ChildNodes

        Dim xn As XmlNode

        For Each xn In xnl

            Dim xe As XmlElement = CType(xn, XmlElement)

            If xe.GetAttribute("genre") = "fantasy" Then

                xe.RemoveAttribute("genre") '删除genre属性

            Else

                If xe.GetAttribute("genre") = "update李赞红" Then

                    xe.RemoveAll() '删除该节点的全部内容

                End If

            End If

        Next xn

        xmlDoc.Save("bookstore.xml")

    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

        Dim xn As XmlNode = xmlDoc.SelectSingleNode("bookstore")

        Dim xnl As XmlNodeList = xn.ChildNodes

        Dim xnf As XmlNode

        For Each xnf In xnl

            Dim xe As XmlElement = CType(xnf, XmlElement)

            Console.WriteLine(xe.GetAttribute("genre")) '显示属性值

            Console.WriteLine(xe.GetAttribute("ISBN"))

            Dim xnf1 As XmlNodeList = xe.ChildNodes

            Dim xn2 As XmlNode

            For Each xn2 In xnf1

                Console.WriteLine(xn2.InnerText) '显示子节点点文本

            Next xn2

        Next xnf

    End Sub

End Class