LINQ - XML
LINQ to XML 以简便的方法访问所有 LINQ 功能，例如标准查询运算符、编程接口等。LINQ to XML 集成在 .NET 框架中，充分利用 .NET 框架功能，例如调试、编译时检查、强类型等等。
LINQ to XML 简介
使用 LINQ to XML，可以轻松地将 XML 文档加载到内存中，并且可以更轻松地查询和修改文档。还可以将存在内存中的 XML 文档保存到磁盘并对其进行序列化。它消除了开发人员学习 XML 查询语言的需要，而 XML 查询语言有点复杂。
LINQ to XML 的功能在 System.Xml.Linq 命名空间中。其中包含用于处理 XML 的所有 19 个必需的类。这些类如下。
- XAttribute
- XCData
- XComment
- XContainer
- XDeclaration
- XDocument
- XDocumentType
- XElement
- XName
- XNamespace
- XNode
- XNodeDocumentOrderComparer
- XNodeEqualityComparer
- XObject
- XObjectChange
- XObjectChangeEventArgs
- XObjectEventHandler
- XProcessingInstruction
- XText
使用 LINQ 读取 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 = @"<Departments>
<Department>Account</Department>
<Department>Sales</Department>
<Department>Pre-Sales</Department>
<Department>Marketing</Department>
</Departments>";
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 = "<Departments>" & vbCr & vbLf &
"<Department>Account</Department>" & vbCr & vbLf &
"<Department>Sales</Department>" & vbCr & vbLf &
"<Department>Pre-Sales</Department>" & vbCr & vbLf &
"<Department>Marketing</Department>" & vbCr & vbLf &
"</Departments>"
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
编译并执行上述 C# 或 VB 代码时，会产生以下结果：
Department Name - Account Department Name - Sales Department Name - Pre-Sales Department Name - Marketing Press any key to continue.
添加新节点
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 = @"<Departments>
<Department>Account</Department>
<Department>Sales</Department>
<Department>Pre-Sales</Department>
<Department>Marketing</Department>
</Departments>";
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 = "<Departments>" & vbCr & vbLf &
"<Department>Account</Department>" & vbCr & vbLf &
"<Department>Sales</Department>" & vbCr & vbLf &
"<Department>Pre-Sales</Department>" & vbCr & vbLf &
"<Department>Marketing</Department>" & vbCr & vbLf &
"</Departments>"
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
编译并执行上述 C# 或 VB 代码时，会产生以下结果：
Department Name - Support Department Name - Account Department Name - Sales Department Name - Pre-Sales Department Name - Marketing Department Name - Finance Press any key to continue.
删除特定节点
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 = @"<Departments>
<Department>Support</Department>
<Department>Account</Department>
<Department>Sales</Department>
<Department>Pre-Sales</Department>
<Department>Marketing</Department>
<Department>Finance</Department>
</Departments>";
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 = "<Departments>" & vbCr & vbLf &
"<Department>Support</Department>" & vbCr & vbLf &
"<Department>Account</Department>" & vbCr & vbLf &
"<Department>Sales</Department>" & vbCr & vbLf &
"<Department>Pre-Sales</Department>" & vbCr & vbLf &
"<Department>Marketing</Department>" & vbCr & vbLf &
"<Department>Finance</Department>" & vbCr & vbLf &
"</Departments>"
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
编译并执行上述 C# 或 VB 代码时，会产生以下结果：
Department Name - Support Department Name - Account Department Name - Pre-Sales Department Name - Marketing Department Name - Finance Press any key to continue.
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