使用XPath命名空间的类的几个小例子

有一books.xml的文件<?xml version='1.0'?>
<!-- This file represents a fragment of a book store inventory database -->
<bookstore>
  <book genre="autobiography" publicationdate="1991" ISBN="1-861003-11-0">
      <title>The Autobiography of Benjamin Franklin</title>
    <author>
      <first-name>Benjamin</first-name>
      <last-name>Franklin</last-name>
    </author>
    <price>8.99</price>
  </book>
  <book genre="novel" publicationdate="1967" ISBN="0-201-63361-2">
    <title>The Confidence Man</title>
    <author>
      <first-name>Herman</first-name>
      <last-name>Melville</last-name>
    </author>
    <price>11.99</price>
  </book>
  <book genre="philosophy" publicationdate="1991" ISBN="1-861001-57-6">
    <title>The Gorgias</title>
    <author>
      <name>Plato</name>
    </author>
    <price>9.99</price>
  </book>
</bookstore>
代码如下:

以下是几个应用的例子

using System;
using System.Xml;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml.Xsl;
using System.Xml.XPath;
namespace XmlWinForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 查看子节点
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnNovels_Click(object sender, EventArgs e)
        {
            XPathDocument doc = new XPathDocument("books.xml");
            XPathNavigator nav = ((IXPathNavigable)doc).CreateNavigator();

            XPathNodeIterator iter = nav.Select("/bookstore/book[@publicationdate='1967']");
            txtXml.Text = "";
            while (iter.MoveNext())
            {
                XPathNodeIterator newIter =
                    iter.Current.SelectDescendants(XPathNodeType.Element, false);

                while (newIter.MoveNext())
                {
                    txtXml.Text += newIter.Current.Name + ":" + newIter.Current.Value + "/r/n";
                }
            }

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
        /// <summary>
        /// 查看子节点 可做统计
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {

            XPathDocument doc = new XPathDocument("books.xml");
            XPathNavigator nav = ((IXPathNavigable)doc).CreateNavigator();
            XPathNodeIterator iter = nav.Select("/bookstore/book");
            txtXml.Text = "";
            while (iter.MoveNext())
            {
                XPathNodeIterator newIter =
                    iter.Current.SelectDescendants(XPathNodeType.Element, false);
                while (newIter.MoveNext())
                {
                    txtXml.Text += newIter.Current.Name + ":" + newIter.Current.Value + "/r/n";

                }
            }
            txtXml.Text += "====================/r/n";
            txtXml.Text += "Total Cost=" + nav.Evaluate("sum(/bookstore/book/price)");

        }
        /// <summary>
        /// 添加 节点
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void addElement_Click(object sender, EventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load("books.xml");
            XPathNavigator nav = doc.CreateNavigator();
            txtXml.Text = "";
            if (nav.CanEdit)
            {
                XPathNodeIterator iter = nav.Select("bookstore/book/price");
                while (iter.MoveNext())
                {
                    txtXml.Text += iter.Current.Name + ":" + iter.Current.Value + "/r/n";
                    iter.Current.InsertBefore("<disc>5</disc>");
                }
            }
            doc.Save("newbooks.xml");
        }
    }
}