C#基础知识---Linq操作XML文件

概述

Linq也就是Language Integrated Query的缩写,即语言集成查询,是微软在.Net 3.5中提出的一项新技术。

Linq主要包含4个组件---Linq to Objects、Linq to XML、Linq to DataSet 和Linq to SQL。

Linq to SQL 组件——可以查询基于关系数据的数据
Linq to Dataset组件——可以查询DasaSet对象中的数据，并对数据进行增删改查的操作
Linq to Objects组件——可以查询IEnumberable 或IEnumberable<T>集合
Linq to XML 组件——可以查询和操作XML文件，比Xpath操作XML更加方便

一、使用Linq创建XML文件

 1  public static class XMLFileHelper
 2         {
 3             /// <summary>
 4             /// Create a xml file
 5             /// </summary>
 6             /// <param name="xmlPath"></param>
 7             private static void CreateXmlFile(string xmlPath)
 8             {
 9                 try
10                 {
11                     //定义一个XDocument结构
12                     object[] content = new object[20];
13                     content[0] = new XElement("User", new XAttribute("Id", "1"),
14                                     new XElement("Name", "Jack"),
15                                     new XElement("Password", "123456"),
16                                     new XElement("Description", "I am Jack")
17                                 );
18                     content[1] = new XElement("User", new XAttribute("Id", "2"),
19                                     new XElement("Name", "Mary"),
20                                     new XElement("Password", "135678"),
21                                     new XElement("Description", "I am Mary")
22                                );
23                     content[2] = new XAttribute("Id", "root");
24 
25                     content[3] = new XElement("User", new XAttribute("Id", "3"),
26                                     new XElement("Name", "Tom"),
27                                     new XElement("Password", "654123"),
28                                     new XElement("Description", "I am Tom")
29                                );
30 
31                     XDocument myXDoc = new XDocument(new XElement("Users", content));
32                     myXDoc.Save(xmlPath);
33                 }
34                 catch (Exception ex)
35                 {
36                     Console.WriteLine(ex.ToString());
37                 }
38             }
39         }

View Code

1 public static void GetXmlNodeInformation(string xmlPath) 2 { 3 try 4 { 5 //定义并从xml文件中加载节点（根节点） 6 XElement rootNode = XElement.Load(xmlPath); 7 //查询语句: 获得根节点下name子节点（此时的子节点可以跨层次：孙节点、重孙节点......） 8 IEnumerable<XElement> targetNodes = from target in rootNode.Descendants("Name") 9 where target.Value.Contains("a") 10 select target; 11 foreach (XElement node in targetNodes) 12 { 13 Console.WriteLine("Name = {0}", node.Value); 14 } 15 Console.WriteLine(); 16 IEnumerable<XElement> myTargetNodes = from myTarget in rootNode.Descendants("User") 17 where myTarget.HasElements 18 select myTarget; 19 foreach (XElement node in myTargetNodes) 20 { 21 Console.WriteLine("Name = {0}", node.Element("Name").Value); 22 Console.WriteLine("Password = {0}", node.Element("Password").Value); 23 Console.WriteLine("Description = {0}", node.Element("Description").Value); 24 Console.WriteLine(); 25 } 26 } 27 catch (Exception ex) 28 { 29 Console.WriteLine(ex.ToString()); 30 } 31 }

1 public static void ModifyXmlNodeInformation(string xmlPath) 2 { 3 try 4 { 5 //定义并从xml文件中加载节点（根节点） 6 XElement rootNode = XElement.Load(xmlPath); 7 IEnumerable<XElement> targetNodes = from target in rootNode.Descendants("User") 8 where target.Element("Name").Value=="Mary" 9 select target; 10 //遍历所获得的目标节点（集合） 11 foreach (XElement node in targetNodes) 12 { 13 //将用户名为Mary的User节点修改为Emma 14 node.Element("Name").SetValue("Emma"); 15 node.Element("Description").SetValue("I am Emma"); 16 } 17 //保存对xml的更改操作 18 rootNode.Save(xmlPath); 19 } 20 catch (Exception ex) 21 { 22 Console.WriteLine(ex.ToString()); 23 } 24 }

1 public static void AddXmlNodeInformation(string xmlPath) 2 { 3 try 4 { 5 //定义并从xml文件中加载节点（根节点） 6 XElement rootNode = XElement.Load(xmlPath); 7 //定义一个新节点 8 XElement newNode = new XElement("User", new XAttribute("Id", "4"), 9 new XElement("Name", "Rose"), 10 new XElement("Password", "333333"), 11 new XElement("Description", "I am Rose")); 12 //将此新节点添加到根节点下 13 rootNode.Add(newNode); 14 //保存对xml的更改操作 15 rootNode.Save(xmlPath); 16 } 17 catch (Exception ex) 18 { 19 Console.WriteLine(ex.ToString()); 20 } 21 }

1 public static void DeleteXmlNodeInformation(string xmlPath) 2 { 3 try 4 { 5 //定义并从xml文件中加载节点（根节点） 6 XElement rootNode = XElement.Load(xmlPath); 7 //查询语句: 获取ID属性值等于"999999"的所有User节点 8 IEnumerable<XElement> targetNodes = from target in rootNode.Descendants("User") 9 let id= Convert.ToInt32(target.Attribute("Id").Value) 10 where id >=3 11 select target; 12 13 targetNodes.Remove(); 14 //保存对xml的更改操作 15 rootNode.Save(xmlPath); 16 17 } 18 catch (Exception ex) 19 { 20 Console.WriteLine(ex.ToString()); 21 } 22 }

1 private static string FileQuery(string targetFileName) 2 { 3 string myDeskTopDir = Environment.GetFolderPath(Environment.SpecialFolder.Desktop); 4 string []fileNames = Directory.GetFiles(myDeskTopDir, "*.*", SearchOption.AllDirectories); 5 List<FileInfo> files = new List<FileInfo>(); 6 foreach(var fileName in fileNames) 7 { 8 files.Add(new FileInfo(fileName)); 9 } 10 var results = from file in files 11 where file.Name == targetFileName 12 select file; 13 StringBuilder queryResult = new StringBuilder(); 14 foreach(var result in results) 15 { 16 queryResult.AppendLine("Query Result:" + result.FullName); 17 } 18 return queryResult.ToString(); 19 }

C#基础知识---Linq操作XML文件

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