DOM /XPath模型處理XML 數據

 1、XML 文檔對象模型(DOM) 類是XML 文檔的內存中表示形式，它在內存中表示是常見的結構化方法，儘管實際的XML 數據在文件中時或從另一個對象傳入時以線性方式存儲。 主要執行DOM 查詢類和方法如下：
• XmlNode 方法
– SelectNodes()
– SelectSingleNode()
• XmlDocument 方法
– GetElementsByTagName()
– GetElementById()
2、XPath
創建XPathNavigator 對象，可以使用CreateNavigator 方法返回XPathNavigator 對象XPathDocument、XmlDocument、XmlNode

using System;
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.Data.SqlClient;
using System.Xml;
using System.Xml.XPath;
namespace UsingDataSet
{
    public partial class Form1 : Form
    {
        string strSQL = null;
        DataSet ds = null;
        public Form1()
        {
            InitializeComponent();
        }      

        private void readToolStripMenuItem_Click(object sender, EventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load(@"D:\Study\XmlControl\UsingXml\Books.xml");
           XmlNode node = doc.DocumentElement;

            foreach (XmlNode xn in node)
            {
                MessageBox.Show(xn.ChildNodes[0].Name + ":"+xn.ChildNodes[0].InnerText);
               
            }

        }
       //SelectNodes
        private void conditToolStripMenuItem_Click(object sender, EventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            //doc.Load(@"D:\Study\XmlControl\UsingXml\ProductXmlXPath.Xml");
            //XmlNodeList nodes = doc.SelectNodes("/Products/Category/ProductName[../ProductID<=2]");
            //ProductXmlXPath.xml 顯示ProductName根據條件ProductID<=2進行選擇

            doc.Load(@"D:\Study\XmlControl\UsingXml\ProductXmlAuto.xml");
            XmlNodeList nodes = doc.SelectNodes("/Products/Product/@ProductName[../@ProductID<=2]");  
           
            foreach (XmlNode xn in nodes)
            {
                MessageBox.Show(xn.ChildNodes[0].Name + ":" + xn.ChildNodes[0].InnerText);
            }       
        }

       //XPathNavigator 
        private void getXmlToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load(@"D:\Study\XmlControl\UsingXml\ProductXmlXPath.Xml");
            XPathNavigator nav = doc.CreateNavigator();
            //XPathNodeIterator iter = nav.Select("/Products/Category/ProductName[../ProductID<=2]");
            //foreach(XmlNode xn in iter)
            MessageBox.Show(nav.OuterXml);
        }      
    }
}