VB.NET中操作xml文件

已知有一个XML文件（bookstore.xml）如下：
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
<book genre="fantasy" ISBN="2-3631-4">

<title>Oberon's Legacy</title>
<author>Corets, Eva</author>
<price>5.95</price>
</book>
</bookstore>

1、往<bookstore>节点中插入一个<book>节点：
Dim xmlDoc As New XmlDocument()
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")
//===============================================
结果为：
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
<book genre="fantasy" ISBN="2-3631-4">
<title>Oberon's Legacy</title>
<author>Corets, Eva</author>
<price>5.95</price>
</book>
<book genre="李赞红" ISBN="2-3631-4">
<title>CS从入门到精通</title>
<author>候捷</author>
<price>58.3</price>
</book>
</bookstore>

2、修改节点：将genre属性值为“李赞红“的节点的genre值改为“update李赞红”，将该节点的子节点<author>的文本修改为“亚胜”。
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 ForEach '找到退出来就可以了
End If
Next xn1
Exit ForEach
End If
Next xn

xmlDoc.Save("bookstore.xml") '保存。
//==================================================
最后结果为：
<?xml version="1.0" encoding="gb2312"?>
<bookstore>
<book genre="fantasy" ISBN="2-3631-4">
<title>Oberon's Legacy</title>
<author>Corets, Eva</author>
<price>5.95</price>
</book>
<book genre="update李赞红" ISBN="2-3631-4">
<title>CS从入门到精通</title>
<author>亚胜</author>
<price>58.3</price>
</book>
</bookstore>

3、删除 <book genre="fantasy" ISBN="2-3631-4">节点的genre属性，删除 <book genre="update李赞红" ISBN="2-3631-4">节点。
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")
//===========================================
最后结果为：
<?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>
<book>
</book>
</bookstore>

4、显示所有数据。
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