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C Sharp 补课笔记 -- LINQ to XML

发表于 更新于 分类于 Valine：
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LINQ to XML 是一种启用了 LINQ 的内存 XML 编程接口，支持在 .NET Framework 编程语言中处理 XML

简单示例

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// Load the XML file from our project directory containing the purchase orders
var filename = "PurchaseOrder.xml";
var currentDirectory = Directory.GetCurrentDirectory();
var purchaseOrderFilepath = Path.Combine(currentDirectory, filename);
XElement purchaseOrder = XElement.Load(purchaseOrderFilepath);
IEnumerable<string> partNos = from item in purchaseOrder.Descendants("Item")select (string) item.Attribute("PartNumber");

IEnumerable<string> partNos = purchaseOrder.Descendants("Item").Select(x => (string)
x.Attribute("PartNumber"));

创建XML

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XElement contacts =
new XElement("Contacts",
    new XElement("Contact",
        new XElement("Name", "Patrick Hines"),
        new XElement("Phone", "206-555-0144",
            new XAttribute("Type", "Home")),
        new XElement("phone", "425-555-0145",
            new XAttribute("Type", "Work")),
        new XElement("Address",
            new XElement("Street1", "123 Main St"),
            new XElement("City", "Mercer Island"),
            new XElement("State", "WA"),
            new XElement("Postal", "68042")
        )
    )
);

LINQ to XML

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XElement srcTree = new XElement("Root",
    new XElement("Element", 1),
    new XElement("Element", 2),
    new XElement("Element", 3),
    new XElement("Element", 4),
    new XElement("Element", 5)
);
XElement xmlTree = new XElement("Root",
    new XElement("Child", 1),
    new XElement("Child", 2),
    from el in srcTree.Elements()
    where (int)el > 2
    select el
);
Console.WriteLine(xmlTree);

XAttribute

创建包含属性的元素

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XElement phone = new XElement("Phone",
    new XAttribute("Type", "Home"),
    "555-555-5555");
Console.WriteLine(phone);
//<Phone Type="Home">555-555-5555</Phone>

XML示例

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XDocument d = new XDocument(
    new XComment("This is a comment."),
    new XProcessingInstruction("xml-stylesheet",
        "href='mystyle.css' title='Compact' type='text/css'"),
    new XElement("Pubs",
        new XElement("Book",
            new XElement("Title", "Artifacts of Roman Civilization"),
            new XElement("Author", "Moreno, Jordao")
        ),
        new XElement("Book",
            new XElement("Title", "Midieval Tools and Implements"),
            new XElement("Author", "Gazit, Inbar")
        )
    ),
    new XComment("This is another comment.")
);
d.Declaration = new XDeclaration("1.0", "utf-8", "true");
Console.WriteLine(d);
d.Save("test.xml");
/*
<?xml version="1.0" encoding="utf-8"?>
<!--This is a comment.-->
<?xml-stylesheet href='mystyle.css' title='Compact' type='text/css'?>
<Pubs>
<Book>
<Title>Artifacts of Roman Civilization</Title>
<Author>Moreno, Jordao</Author>
</Book>
<Book>
<Title>Midieval Tools and Implements</Title>
<Author>Gazit, Inbar</Author>
</Book>
</Pubs>
<!--This is another comment.-->
*/