IT工程師數位筆記本

<?xml version="1.0" encoding="utf-8" ?>
<pets>
  <cat color="black" weight="10">
    <price>100</price>
    <desc>this is a black cat</desc>
  </cat>
  <cat color="white" weight="9">
    <price>80</price>
    <desc>this is a white cat</desc>
  </cat>
  <cat color="yellow" weight="15">
    <price>80</price>
    <desc>this is a yellow cat</desc>
  </cat>
 
 
  <dog color="black" weight="10">
    <price>100</price>
    <desc>this is a black dog</desc>
  </dog>
  <dog color="white" weight="9">
    <price>80</price>
    <desc>this is a white dog</desc>
  </dog>
  <dog color="yellow" weight="15">
    <price>80</price>
    <desc>this is a yellow dog</desc>
  </dog>
</pets>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.XPath;
using System.Xml;
 
namespace UseXPathDotNet
{
    class Program
    {
        static void Main(string[] args)
        {
            UseXPathWithXPathDocument();
 
            UseXPathWithXmlDocument();
 
            Console.Read();
        }
 
        static void UseXPathWithXmlDocument()
        {
            XmlDocument doc = new XmlDocument();
            doc.Load("http://www.cnblogs.com/yukaizhao/rss");
            //使用xPath選擇需要的節點
            XmlNodeList nodes = doc.SelectNodes("/rss/channel/item[position()<=10]");
            foreach (XmlNode item in nodes)
            {
                string title = item.SelectSingleNode("title").InnerText;
                string url = item.SelectSingleNode("link").InnerText;
                Console.WriteLine("{0} = {1}", title, url);
            }
        }
 
        static void UseXPathWithXPathDocument()
        {
            XPathDocument doc = new XPathDocument("http://www.cnblogs.com/yukaizhao/rss");
            XPathNavigator xPathNav = doc.CreateNavigator();
            //使用xPath取rss中最新的10條隨筆
            XPathNodeIterator nodeIterator = xPathNav.Select("/rss/channel/item[position()<=10]");
            while (nodeIterator.MoveNext())
            {
                XPathNavigator itemNav = nodeIterator.Current;
                string title = itemNav.SelectSingleNode("title").Value;
                string url = itemNav.SelectSingleNode("link").Value;
                Console.WriteLine("{0} = {1}",title,url);
            }
 
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Xml;
 
namespace UseXPath1
{
    class Program
    {
        static void Main(string[] args)
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-8"" ?>
<pets>
  <cat color=""black"" weight=""10"" count=""4"">
    <price>100</price>
    <desc>this is a black cat</desc>
  </cat>
  <cat color=""white"" weight=""9"" count=""5"">
    <price>80</price>
    <desc>this is a white cat</desc>
  </cat>
  <cat color=""yellow"" weight=""15"" count=""1"">
    <price>110</price>
    <desc>this is a yellow cat</desc>
  </cat>
 
 
  <dog color=""black"" weight=""10"" count=""7"">
    <price>114</price>
    <desc>this is a black dog</desc>
  </dog>
  <dog color=""white"" weight=""9"" count=""4"">
    <price>80</price>
    <desc>this is a white dog</desc>
  </dog>
  <dog color=""yellow"" weight=""15"" count=""15"">
    <price>80</price>
    <desc>this is a yellow dog</desc>
  </dog>
 
    <pig color=""white"" weight=""100"" count=""2"">
    <price>8000</price>
    <desc>this is a white pig</desc>    
    </pig>
</pets>";
 
            using (StringReader rdr = new StringReader(xml))
            {
                XmlDocument doc = new XmlDocument();
                doc.Load(rdr);
 
                //取所有pets節點下的dog字節點
                XmlNodeList nodeListAllDog = doc.SelectNodes("/pets/dog");
 
                //所有的price節點
                XmlNodeList allPriceNodes = doc.SelectNodes("//price");
 
                //取最后一個price節點
                XmlNode lastPriceNode = doc.SelectSingleNode("//price[last()]");
 
                //用雙點號取price節點的父節點
                XmlNode lastPriceParentNode = lastPriceNode.SelectSingleNode("..");
 
                //選擇weight*count=40的所有動物，使用通配符*
                XmlNodeList nodeList = doc.SelectNodes("/pets/*[@weight*@count=40]");
 
                //選擇除了pig之外的所有動物,使用name()函數返回節點名字
                XmlNodeList animalsExceptPigNodes = doc.SelectNodes("/pets/*[name() != 'pig']");
                
 
                //選擇價格大于100而不是pig的動物
                XmlNodeList priceGreaterThan100s = doc.SelectNodes("/pets/*[price div @weight >10 and name() != 'pig']");
                foreach (XmlNode item in priceGreaterThan100s)
                {
                    Console.WriteLine(item.OuterXml);
                }
 
                //選擇第二個dog節點
                XmlNode theSecondDogNode = doc.SelectSingleNode("//dog[position() = 2]");
 
                //使用xpath ，axes 的 parent 取父節點
                XmlNode parentNode = theSecondDogNode.SelectSingleNode("parent::*");
 
                //使用xPath選擇第二個dog節點前面的所有dog節點
                XmlNodeList dogPresibling = theSecondDogNode.SelectNodes("preceding::dog");
 
                //取文檔的所有子孫節點price
                XmlNodeList childrenNodes = doc.SelectNodes("descendant::price");
            }
 
            Console.Read();
        }
    }
}