XPath简单示例

最新推荐文章于 2020-06-06 12:11:27 发布

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最新推荐文章于 2020-06-06 12:11:27 发布

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分类专栏： C＃专区文章标签： string encoding class file xml

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本文通过一个具体的XML文件示例，介绍了如何使用XPath表达式来选取XML文档中的节点。包括选择所有顶级节点、特定名称的子节点、第一个或最后一个节点、特定属性值的节点等。

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Xml文件内容:

<?xml version="1.0" encoding="utf-8" ?> <bookstore> <book> <title lang="eng">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="eng">Learning XML</title> <price>39.95</price> </book> </bookstore>
XPath简单示例:

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Xml; namespace XpathTest { class Program { static void Main(string[] args) { //load BookStore.xml file XmlDocument xmlDoc = new XmlDocument(); xmlDoc.Load(@"../../BookStore.xml"); //bookstore:select all nodes with name 'bookstore' var bookSubNodes = xmlDoc.SelectNodes(@"bookstore"); OutPutNodes(@"bookstore", bookSubNodes); //bookstore/book:select all nodes with name 'book' under 'bookstore' bookSubNodes = xmlDoc.SelectNodes(@"bookstore/book"); OutPutNodes(@"bookstore/book", bookSubNodes); //bookstore/book[1]:select first node with name 'book' under 'bookstore' bookSubNodes = xmlDoc.SelectNodes(@"bookstore/book[1]"); OutPutNodes(@"bookstore/book[1]", bookSubNodes); //bookstore/book[last()]:select last node with name 'book' under 'bookstore' bookSubNodes = xmlDoc.SelectNodes(@"bookstore/book[last()]"); OutPutNodes(@"bookstore/book[last()]", bookSubNodes); ////title:select all nodes with name 'title' everywhere under current node bookSubNodes = xmlDoc.SelectNodes(@"//title"); OutPutNodes(@"//title", bookSubNodes); //bookstore/book[price>35.00]:select all nodes with name 'book' and price > 35.00 under 'bookstore' bookSubNodes = xmlDoc.SelectNodes(@"bookstore/book[price>35.00]"); OutPutNodes(@"bookstore/book[price>35.00]", bookSubNodes); ////book/title | //book/price:select all nodes with name 'title' or 'price' under 'book' everywhere bookSubNodes = xmlDoc.SelectNodes(@"//book/title | //book/price"); OutPutNodes(@"//book/title | //book/price", bookSubNodes); ////@lang:select all atrributes with name 'lang' everywhere under current node bookSubNodes = xmlDoc.SelectNodes(@"//@lang"); OutPutNodes(@"//@lang", bookSubNodes); Console.Read(); } static void OutPutNodes(string name, XmlNodeList nodes) { StringBuilder nodeName = new StringBuilder(); foreach (XmlNode node in nodes) { nodeName.Append(node.Name + " "); } Console.WriteLine(name + ":"); Console.WriteLine(nodeName + "/n"); } } }

输出结果:

bookstore:
bookstore

bookstore/book:
book book

bookstore/book[1]:
book

bookstore/book[last()]:
book

//title:
title title

bookstore/book[price>35.00]:
book

//book/title | //book/price:
title price title price

//@lang:
lang lang