LINQ to XML：应用 XPath

使用XPath是一种在LINQ to XML中查询和筛选XML文档的强大工具。XPath使用路径表达式来选取XML文档中的节点或节点集。通过使用XPath，我们可以轻松地在XML文档中定位和提取所需的数据。

csharp
XDocument xmlDoc = XDocument.Load("books.xml");
// 使用XPath选择所有的书籍节点
IEnumerable books = xmlDoc.XPathSelectElements("//book");
foreach (XElement book in books)
{
    Console.WriteLine(book.Element("title").Value);
    Console.WriteLine(book.Element("author").Value);
    Console.WriteLine();
}

csharp
XDocument xmlDoc = XDocument.Load("books.xml");
// 使用XPath筛选作者为"John Doe"的书籍节点
IEnumerable books = xmlDoc.XPathSelectElements("//book[author='John Doe']");
foreach (XElement book in books)
{
    Console.WriteLine(book.Element("title").Value);
    Console.WriteLine(book.Element("author").Value);
    Console.WriteLine();
}

csharp
XDocument xmlDoc = XDocument.Load("books.xml");
// 使用XPath导航到标题为"C# in Depth"的书籍节点的父节点
XElement book = xmlDoc.XPathSelectElement("//book[title='C# in Depth']");
XElement parent = book.Parent;
Console.WriteLine(parent.Element("title").Value);
Console.WriteLine(parent.Element("author").Value);
Console.WriteLine();

csharp
using System;
using System.Xml.Linq;
using System.Xml.XPath;
class Program
{
    static void Main(string[] args)
    {
        XDocument xmlDoc = XDocument.Load("books.xml");
        // 使用XPath选择所有的书籍节点
        IEnumerable books = xmlDoc.XPathSelectElements("//book");
        foreach (XElement book in books)
        {
            Console.WriteLine(book.Element("title").Value);
            Console.WriteLine(book.Element("author").Value);
            Console.WriteLine();
        }
        // 使用XPath筛选作者为"John Doe"的书籍节点
        IEnumerable johnDoeBooks = xmlDoc.XPathSelectElements("//book[author='John Doe']");
        foreach (XElement book in johnDoeBooks)
        {
            Console.WriteLine(book.Element("title").Value);
            Console.WriteLine(book.Element("author").Value);
            Console.WriteLine();
        }
        // 使用XPath导航到标题为"C# in Depth"的书籍节点的父节点
        XElement csharpInDepthBook = xmlDoc.XPathSelectElement("//book[title='C# in Depth']");
        XElement parent = csharpInDepthBook.Parent;
        Console.WriteLine(parent.Element("title").Value);
        Console.WriteLine(parent.Element("author").Value);
        Console.WriteLine();
    }
}