XmlDocument和LINQ to XML两种方式对xml的创建、查询

<?xml version="1.0" encoding="UTF-8"?>
<Persons xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.xxx.com/XxxSystem">
<Person id="1">
<Name>张三</Name>
<Age>18</Age>
</Person>
<Person id="2">
<Name>李四</Name>
<Age>20</Age>
</Person>
</Persons>

private void button1_Click(object sender, EventArgs e)
{
XmlDocument doc = new XmlDocument();
XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", "UTF-8", null);
doc.AppendChild(dec);
//根节点
XmlElement root = doc.CreateElement("Persons");
doc.AppendChild(root);
root.AddEleAttr(doc, "xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance");
root.AddEleAttr(doc, "xmlns", "http://www.xxx.com/XxxSystem");
//根节点的每个独立子节点
XmlElement body = doc.CreateElement("Person");
body.AddEleAttr(doc, "id", "1");
body.AddChildNode(doc, "Name", "张三");
body.AddChildNode(doc, "Age", "18");
root.AppendChild(body);

//根节点的每个独立子节点
body = doc.CreateElement("Person");
body.AddEleAttr(doc, "id", "2");
body.AddChildNode(doc, "Name", "李四");
body.AddChildNode(doc, "Age", "20");
root.AppendChild(body);

doc.Save("person.xml");
}

private void button2_Click(object sender, EventArgs e)
{
XmlDocument doc = new XmlDocument();
using (StreamReader sr = new StreamReader("person.xml", Encoding.UTF8))
{
doc.Load(sr);
XmlNamespaceManager nsMgr = new XmlNamespaceManager(doc.NameTable);
nsMgr.AddNamespace("ns", "http://www.xxx.com/XxxSystem");
XmlNodeList nodes = doc.SelectNodes("//ns:Person[@id=2]", nsMgr);
foreach (XmlNode item in nodes)
{
string name = item.SelectSingleNode("//ns:Name", nsMgr).InnerText;
string age = item.SelectSingleNode("//ns:Age", nsMgr).InnerText;
MessageBox.Show(string.Format("{0}:{1}", name, age));
}
}
}

/// <summary>
/// XML元素添加属性
/// </summary>
public static void AddEleAttr(this XmlElement src, XmlDocument doc, string name, string value)
{
XmlAttribute attr = doc.CreateAttribute(name);
attr.Value = value;
src.Attributes.Append(attr);
}
/// <summary>
/// XML元素添加子节点
/// </summary>
public static void AddChildNode(this XmlElement src, XmlDocument doc, string name, string innerText)
{
XmlElement elem = doc.CreateElement(name);
elem.InnerText = innerText;
src.AppendChild(elem);
}

//using System.Xml.Linq;
private void button1_Click(object sender, EventArgs e)
{
XNamespace ns = "http://www.xxx.com/XxxSystem";
XDocument doc = new XDocument(
new XDeclaration("1.0","UTF-8",null),
new XElement(ns + "Persons",
new XAttribute(XNamespace.Xmlns + "xsi", "http://www.w3.org/2001/XMLSchema-instance"),
new XElement("Person",
new XAttribute("id","1"),
new XElement("Name","张三"),
new XElement("Age",18)
),
new XElement("Person",
new XAttribute("id", "2"),
new XElement("Name", "李四"),
new XElement("Age", 20)
)
)
);
doc.Save("person.xml");
}

private void button2_Click(object sender, EventArgs e)
{
using (StreamReader sr = new StreamReader("person.xml", Encoding.UTF8))
{
XDocument doc = XDocument.Load(sr);
XNamespace ns = "http://www.xxx.com/XxxSystem";
var qry = doc.Descendants(ns + "Persons")
.Elements(ns + "Person")
.Where(p => p.Attribute("id").Value == "2")
.Select(p => new
{
Name = p.Element(ns + "Name").Value,
Age = p.Element(ns + "Age").Value
});
foreach(var p in qry)
MessageBox.Show(string.Format("{0}:{1}", p.Name, p.Age));
}
}