LINQ XML

LINQ到XML提供易於訪問所有的LINQ功能類似於標準查詢操作，編程接口等。 集成在.NET框架的LINQ to XML也使得物盡其用的.NET框架的功能像調試，編譯時檢查，強類型。

LINQ 到 XML介紹

雖然使用LINQ 到 XML，加載XML文檔到內存容易，更容易被查詢和修改文檔。另外，也可以保存在現有的存儲器磁盤的XML文檔，並對其進行序列化。它省去了一個開發人員學習XML查詢語言這是有點複雜的。

LINQ到XML有它在System.Xml.Linq的命名。這是過去19個必要的類使用XML。這些類如以下所示。

• XAttribute
• XCData
• XComment
• XContainer
• XDeclaration
• XDocument
• XDocumentType
• XElement
• XName
• XNamespace
• XNode
• XNodeDocumentOrderComparer
• XNodeEqualityComparer
• XObject
• XObjectChange
• XObjectChangeEventArgs
• XObjectEventHandler
• XProcessingInstruction
• XText

使用LINQ讀取XML文件

C#

using System; using System.Collections.Generic; using System.Linq; using System.Xml.Linq; namespace LINQtoXML { class ExampleOfXML { static void Main(string[] args) { string myXML = @"
Account
Sales
Pre-Sales
Marketing
"; XDocument xdoc = new XDocument(); xdoc = XDocument.Parse(myXML); var result = xdoc.Element("Departments").Descendants(); foreach (XElement item in result) { Console.WriteLine("Department Name - " + item.Value); } Console.WriteLine("\nPress any key to continue."); Console.ReadKey(); } } }

VB

Imports System.Collections.Generic Imports System.Linq Imports System.Xml.Linq Module Module1 Sub Main(ByVal args As String()) Dim myXML As String = "" & vbCr & vbLf & "Account" & vbCr & vbLf & "Sales" & vbCr & vbLf & "Pre-Sales" & vbCr & vbLf & "Marketing" & vbCr & vbLf & "" Dim xdoc As New XDocument() xdoc = XDocument.Parse(myXML) Dim result = xdoc.Element("Departments").Descendants() For Each item As XElement In result Console.WriteLine("Department Name - " + item.Value) Next Console.WriteLine(vbLf & "Press any key to continue.") Console.ReadKey() End Sub End Module

當C＃或VB的上述代碼被編譯和執行時，它產生了以下結果：

Department Name - Account
Department Name - Sales
Department Name - Pre-Sales
Department Name - Marketing

Press any key to continue.

添加新節點

C#

using System; using System.Collections.Generic; using System.Linq; using System.Xml.Linq; namespace LINQtoXML { class ExampleOfXML { static void Main(string[] args) { string myXML = @"
Account
Sales
Pre-Sales
Marketing
"; XDocument xdoc = new XDocument(); xdoc = XDocument.Parse(myXML); //Add new Element xdoc.Element("Departments").Add(new XElement("Department", "Finance")); //Add new Element at First xdoc.Element("Departments").AddFirst(new XElement("Department", "Support")); var result = xdoc.Element("Departments").Descendants(); foreach (XElement item in result) { Console.WriteLine("Department Name - " + item.Value); } Console.WriteLine("\nPress any key to continue."); Console.ReadKey(); } } }

VB

Imports System.Collections.Generic Imports System.Linq Imports System.Xml.Linq Module Module1 Sub Main(ByVal args As String()) Dim myXML As String = "" & vbCr & vbLf & "Account" & vbCr & vbLf & "Sales" & vbCr & vbLf & "Pre-Sales" & vbCr & vbLf & "Marketing" & vbCr & vbLf & "" Dim xdoc As New XDocument() xdoc = XDocument.Parse(myXML) xdoc.Element("Departments").Add(New XElement("Department", "Finance")) xdoc.Element("Departments").AddFirst(New XElement("Department", "Support")) Dim result = xdoc.Element("Departments").Descendants() For Each item As XElement In result Console.WriteLine("Department Name - " + item.Value) Next Console.WriteLine(vbLf & "Press any key to continue.") Console.ReadKey() End Sub End Module

當C＃或VB的上述代碼被編譯和執行時，它產生了以下結果：

Department Name - Support
Department Name - Account
Department Name - Sales
Department Name - Pre-Sales
Department Name - Marketing
Department Name - Finance

Press any key to continue.

刪除特定節點

C#

using System; using System.Collections.Generic; using System.Linq; using System.Xml.Linq; namespace LINQtoXML { class ExampleOfXML { static void Main(string[] args) { string myXML = @"
Support
Account
Sales
Pre-Sales
Marketing
Finance
"; XDocument xdoc = new XDocument(); xdoc = XDocument.Parse(myXML); //Remove Sales Department xdoc.Descendants().Where(s =>s.Value == "Sales").Remove(); var result = xdoc.Element("Departments").Descendants(); foreach (XElement item in result) { Console.WriteLine("Department Name - " + item.Value); } Console.WriteLine("\nPress any key to continue."); Console.ReadKey(); } } }

VB

Imports System.Collections.Generic Imports System.Linq Imports System.Xml.Linq Module Module1 Sub Main(args As String()) Dim myXML As String = "" & vbCr & vbLf & "Support" & vbCr & vbLf & "Account" & vbCr & vbLf & "Sales" & vbCr & vbLf & "Pre-Sales" & vbCr & vbLf & "Marketing" & vbCr & vbLf & "Finance" & vbCr & vbLf & "" Dim xdoc As New XDocument() xdoc = XDocument.Parse(myXML) xdoc.Descendants().Where(Function(s) s.Value = "Sales").Remove() Dim result = xdoc.Element("Departments").Descendants() For Each item As XElement In result Console.WriteLine("Department Name - " + item.Value) Next Console.WriteLine(vbLf & "Press any key to continue.") Console.ReadKey() End Sub End Module

當C＃或VB的上述代碼被編譯和執行時，它產生了以下結果：

Department Name - Support
Department Name - Account
Department Name - Pre-Sales
Department Name - Marketing
Department Name - Finance

Press any key to continue.