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C#教程之c#通过xpath读取xml示例
需要修改Main方法第一行代码的路径为你的books.xml文件绝对路径或相对路径。代码演示了XPath各种语法的使用情况
books.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>
主程序
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
namespace XmlProcessTest
{
public class Program
{
/// <summary>
/// 加载XML文件
/// </summary>
/// <param name="xmlFilePath">XML文件路径</param>
/// <returns></returns>
public static XmlDocument LoadXmlDoc(string xmlFilePath)
{
var xmlDoc = new XmlDocument();
xmlDoc.Load(xmlFilePath);
return xmlDoc;
}
/// <summary>
/// 根据指定的XPath表达式获取XML结点列表
/// </summary>
/// <param name="xmlDoc"></param>
/// <param name="xpathExpr"></param>
/// <returns></returns>
public static XmlNodeList GetXmlNodes(XmlDocument xmlDoc, string xpathExpr)
{
if (xmlDoc == null)
return null;
return xmlDoc.SelectNodes(xpathExpr);
}
public static string GetXmlNodeInfo(XmlNode node, string type="xml")
{
if (node == null)
return "Empty node or error node";
string xmlNodeInfo = null;
switch (type)
{
case "text":
xmlNodeInfo = node.InnerText;
break;
default:
xmlNodeInfo = node.InnerXml;
break;
}
return xmlNodeInfo;
}
public static void Main(string[] args)
{
var xmlDoc = LoadXmlDoc(@"你的books.xml文件路径");
var rootExpr = "/bookstore"; // 根节点对应的XPath表达式
var rootNode = GetXmlNodes(xmlDoc, rootExpr); //
Console.WriteLine("XPath表达式为 /bookstore，根节点bookstore的所有子节点XML内容如下：");
Console.WriteLine(GetXmlNodeInfo(rootNode[0]));
Console.WriteLine();
var allBooksExpr = "/bookstore/book"; // 根节点bookstore的子元素的所有子节点
var bookNodes = GetXmlNodes(xmlDoc, allBooksExpr);
Console.WriteLine("XPath表达式为 bookstore/book，book节点共有：" + bookNodes.Count);
Console.WriteLine();
var anyBookExpr = "//book"; // 选取所有book子元素，而不管它们在文档中的位置
var anyBookNodes = GetXmlNodes(xmlDoc, anyBookExpr);
Console.WriteLine("XPath表达式为 //book，book节点共有：" + anyBookNodes.Count);
Console.WriteLine(anyBookNodes[0].InnerXml);
Console.WriteLine(anyBookNodes[0].OuterXml);
Console.WriteLine();
var categoryExpr = "//@category"; // 选取名为category的所有属性
var allCategoryNodes = GetXmlNodes(xmlDoc, categoryExpr);
Console.WriteLine("XPath表达式为 //@category，category节点共有：" + allCategoryNodes.Count);
Console.WriteLine(allCategoryNodes[0].InnerText);
Console.WriteLine(allCategoryNodes[0].InnerXml);
Console.WriteLine();
var titleWithLangExpr = "//title[@lang]"; // 选取所有带有lang属性的title节点
var titleWithLangNodes = GetXmlNodes(xmlDoc, titleWithLangExpr);
Console.WriteLine("XPath表达式为 //title[@lang]，带lang属性的title节点共有：" + titleWithLangNodes.Count);
Console.WriteLine(GetXmlNodeInfo(titleWithLangNodes[0]));
var englishTitleExpr = "//title[@lang='en']"; // 选取所有lang属性值为en的title节点
var englishTitleNodes = GetXmlNodes(xmlDoc, englishTitleExpr);
Console.WriteLine("XPath表达式为 //title[@lang='en']，lang属性值为en的title节点共有：" + englishTitleNodes.Count);
Console.WriteLine(GetXmlNodeInfo(englishTitleNodes[0]));
Console.WriteLine();
// 使用索引的XPath查询
var indexExpr = "/bookstore/book[1]"; // 取bookstore子元素的第一个book元素
var firstBookNode = GetXmlNodes(xmlDoc, indexExpr);
Console.WriteLine("XPath表达式为 /bookstore/book[1]，节点数为：" + firstBookNode.Count);
Console.WriteLine(GetXmlNodeInfo(firstBookNode[0]));
Console.WriteLine();
var indexExpr2 = "/bookstore/book[last()]"; // 取bookstore子元素的最后一个book元素
var lastBookNode = GetXmlNodes(xmlDoc, indexExpr2);
Console.WriteLine("XPath表达式为 /bookstore/book[last()]，节点数为：" + lastBookNode.Count);
Console.WriteLine(GetXmlNodeInfo(lastBookNode[0]));
Console.WriteLine();
var indexExpr3 = "/bookstore/book[last()-1]"; // 取bookstore子元素的倒数第二个book元素
var nextByLastBookNode = GetXmlNodes(xmlDoc, indexExpr3);
Console.WriteLine("XPath表达式为 /bookstore/book[last()-1]，节点数为：" + lastBookNode.Count);
Console.WriteLine(GetXmlNodeInfo(nextByLastBookNode[0]));
Console.WriteLine();
var indexExpr4 = "/bookstore/book[position()<3]"; // 取bookstore的前两个book子元素
var firstTwoBookNodes = GetXmlNodes(xmlDoc, indexExpr4);
Console.WriteLine("XPath表达式为 /bookstore/book[position()<3]，节点数为：" + firstTwoBookNodes.Count);
Console.WriteLine(GetXmlNodeInfo(firstTwoBookNodes[0]));
Console.WriteLine();
// 带属性值过滤条件的XPath表达式
var fileterExpr = "/bookstore/book[price>35.00]"; // 选取bookstore的所有price属性值大于35.00的book元素
var bookGt35Nodes = GetXmlNodes(xmlDoc, fileterExpr);
Console.WriteLine("XPath表达式为 /bookstore/book[price>35.00]，节点数为：" + bookGt35Nodes.Count);
Console.WriteLine(GetXmlNodeInfo(bookGt35Nodes[0]));
// 通配符
// @* 匹配任何属性节点
// node() 匹配任何类型的节点
// /bookstore/* 选取 bookstore 元素的所有子元素
// //* 选取文档的所有元素
// //title[@*] 选取所有带有属性的 title 元素
var allTitleWithAttrExpr = "//title[@*]";
var allTitleWithAttrNodes = GetXmlNodes(xmlDoc, allTitleWithAttrExpr);
Console.WriteLine("XPath表达式为 title[@*]，节点数为：" + allTitleWithAttrNodes.Count);
Console.WriteLine(GetXmlNodeInfo(allTitleWithAttrNodes[0]));
Console.WriteLine();
// | 或
var titleAndPriceExpr = "//book/title | //book/price";
var titleAndPriceNodes = GetXmlNodes(xmlDoc, titleAndPriceExpr);
Console.WriteLine("XPath表达式为 //book/title | //book/price，节点数为：" + titleAndPriceNodes.Count);
Console.WriteLine(GetXmlNodeInfo(titleAndPriceNodes[0]));
// text() 选取文本
var titleTextExpr = "//title/text()";
var titleTextNodes = GetXmlNodes(xmlDoc, titleTextExpr);
Console.WriteLine("XPath表达式为 //title/text()，节点数为：" + titleTextNodes.Count);
Console.WriteLine(titleTextNodes[0].Value); // 文本节点的值
Console.ReadKey();
}
}
}
