Linq To Xml 之XDocument, XElement的使用

最新推荐文章于 2025-08-03 16:22:45 发布

转载最新推荐文章于 2025-08-03 16:22:45 发布 · 102 阅读

本文介绍使用LINQ查询XML文件的方法，展示了如何加载XML文件并执行基本查询，包括按类别筛选书籍及小说等。

0. 准备：products.xml的定义：

<?xml version="1.0" encoding="utf-8"?>

<products>
  <product id="product1" category="book">
    <name>Programing Something</name>
    <price>2000</price>
    <publishDate>2008/10/10</publishDate>
    <authors>
        <author>Tarou Book</author>
        <author>Hanako Book</author>
    </authors>
  </product>
  <product id="product2" category="book">
    <name>Administrating Something</name>
    <price>5000</price>
    <publishDate>2008/10/12</publishDate>
    <authors>
        <author>Kotarou Book1</author>
        <author>Kohanako Book2</author>
    </authors>
  </product>
  <product id="product3" category="novel">
    <name>Suspection novel</name>
    <price>500</price>
    <publishDate>2007/12/12</publishDate>
    <authors>
        <author>Jirou Tarou</author>
    </authors>
  </product>
  <product id="product4" category="novel">
    <name>Fantasy novel</name>
    <price>540</price>
    <publishDate>2008/9/14</publishDate>
    <authors>
        <author>Tarou Book</author>
    </authors>
  </product>
  <product id="product5" category="cram">
    <name>Study English</name>
    <price>2400</price>
    <publishDate>2008/9/14</publishDate>
    <authors>
        <author>English Tarou</author>
        <author>English Jirou</author>
    </authors>
  </product>
</products>

1.Linq To XML
1.1 加载XML文件

通过XDocument，XElement的Load方法读入XML文件，进行XDocument和XElement的初期化。

XElement elem = XElement.Load(@"D:/VisualStudioProject2008/Test/Linq2XML01/products.xml");

Console.WriteLine(elem);

XDocument doc = XDocument.Load(@"D:/VisualStudioProject2008/Test/Linq2XML01/products.xml");

Console.WriteLine(doc.ToString());

1.2 选择处理

如下代码所示，通过Linq对xml进行查询。

XElement products = XElement.Load(@"D:/VisualStudioProject2008/Test/Linq2XML01/products.xml");

var query = from p in products.Elements("product")

where (string)p.Attribute("category") == "book"

select new

{

ID = (string)p.Attribute("id"),

Name = (string)p.Element("name"),

Price = (decimal)p.Element("price")

};

foreach (var item in query)

{

Console.WriteLine(item);

}

执行结果如下：

{ ID = product1, Name = Programing Something, Price = 2000 }
{ ID = product2, Name = Administrating Something, Price = 5000 }

更复杂的应用，比如：通过Join一个String数组（书类型的集合）来查询。

view plainvar categories = new string[] { "book", "novel" };

// 在on里直接写p.Element("category")是无法编译通过的，

// 必须显示转换为string类型之后比较：(string) p.Element("category")

var query = from p in products.Elements("product")

let xCategory = (string) p.Attribute("category")

join c in categories

on xCategory equals c

orderby xCategory

select new

{

Name = (string)p.Element("name"),

Price = (decimal)p.Element("price"),

Category = xCategory

};

foreach (var item in query)

{

Console.WriteLine(item);

}

执行结果：

{ Name = Programing Something, Price = 2000, Category = book }
{ Name = Administrating Something, Price = 5000, Category = book }
{ Name = Suspection novel, Price = 500, Category = novel }
{ Name = Fantasy novel, Price = 540, Category = novel }