C#学习——7.xml文件读写_c# xml文件-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_22170875/article/details/104783800

本文详细介绍使用C#通过XmlDocument和XDocument类进行XML文件的读写操作，包括构造数据信息、写入XML文件、读取XML文件并将信息加载到TreeView中。

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一、程序介绍

1.界面设计

在这里插入图片描述

2.设计思路

点击写入xml按钮，将构造的数据信息写入指定的xml文件，然后点击读xml按钮将xml文件中的信息读取并循环加载显示到TreeView中。点击读取指定节点时，显示xml文件中name节点的个数。

3.构造数据信息：

//0.全校学生信息集合
Dictionary<string, List<Student>> allstudengts = new Dictionary<string, List<Student>>();

List<Student> class1List = new List<Student>();
class1List.Add(new Student("张三", 16, "c101"));
class1List.Add(new Student("李四", 23, "c102"));
class1List.Add(new Student("王五", 31, "c103"));
allstudengts.Add("c100", class1List);

List<Student> class2List = new List<Student>();
class2List.Add(new Student("李诞", 32, "c201"));
class2List.Add(new Student("池子", 18, "c202"));
class2List.Add(new Student("卡姆", 29, "c203"));
allstudengts.Add("c200", class2List);

二、XmlDocument类

1、写方法

#region 1.【XmlDocument】方法写入xml文件
//1.1实例化xml对象，并添加文档说明信息
XmlDocument xml = new XmlDocument();
XmlDeclaration xmldeclaration = xml.CreateXmlDeclaration("1.0", "utf-8", "yes");
xml.AppendChild(xmldeclaration);

//1.2根节点：学校
XmlElement rootElement = xml.CreateElement("school");
xml.AppendChild(rootElement);
//依次写入各个班级学生信息
foreach (var item in allstudengts)
{
     //1.3根节点的子节点：班级
     XmlElement classElement = xml.CreateElement("class");
     //创建属性
     XmlAttribute classAttribute = xml.CreateAttribute("id");
     classAttribute.Value = item.Key;
     classElement.Attributes.Append(classAttribute);
     rootElement.AppendChild(classElement);
     //依次该班级每名学生信息
     foreach (Student stu in item.Value)
     {
         //1.4班级节点的子节点：学生
         XmlElement studentElement = xml.CreateElement("student");
         XmlAttribute studentAttribute = xml.CreateAttribute("sid");
         studentAttribute.Value = stu.SId;
         studentElement.Attributes.Append(studentAttribute);

         //1.5学生子节点：姓名、年龄
         XmlElement nameElement = xml.CreateElement("name");
         nameElement.InnerText = stu.Name;

         XmlElement ageElement = xml.CreateElement("age");
         ageElement.InnerText = stu.Age.ToString();

         //1.6依次插入节点到根节点
         classElement.AppendChild(studentElement);
         studentElement.AppendChild(nameElement);
         studentElement.AppendChild(ageElement);
    }
}

//2.写入文件(没有根节点不能写入)
xml.Save("demo.xml");
#endregion

2、读方法

#region 2.读取xml文件(XmlDocument)
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load("demo2.xml");
//获取根节点
XmlElement rootElement = xmlDoc.DocumentElement;
//将根节点加载到TreeView上
TreeNode rootNode = treeView1.Nodes.Add(rootElement.Name);
//递归加载
LoadXmlByXmlDocument(rootElement, rootNode.Nodes);
rootNode.Expand();
#endregion

LoadXmlByXmlDocument()函数定义如下：

//读取xml文件(XmlDocument)
private void LoadXmlByXmlDocument(XmlElement rootElement, TreeNodeCollection treeNodeCollection)
{
   //循环rootElement下的所有子元素（直接子元素）
   foreach (XmlNode item in rootElement.ChildNodes)
   {
         if (item.NodeType == XmlNodeType.Element)
         {
              TreeNode node =  treeNodeCollection.Add(item.Name);
              LoadXmlByXmlDocument((XmlElement)item, node.Nodes);
         }
         else if (item.NodeType == XmlNodeType.Text || item.NodeType == XmlNodeType.CDATA)
         {
              treeNodeCollection.Add(item.InnerText);
         }
    }
}

三、XDocument类

1、写方法

//1.创建dom对象
XDocument xDoc = new XDocument();
XDeclaration xDec = new XDeclaration("1.0", "utf-8", null);
xDoc.Declaration = xDec;

//2.创建根节点
XElement rootElement = new XElement("school");
xDoc.Add(rootElement);

//3.循环加载学生信息
foreach (var item in allstudengts)
{
    //根节点的子节点：班级
    XElement classElement = new XElement("class");
    classElement.SetAttributeValue("cid", "c100");
    rootElement.Add(classElement);

    //依次该班级每名学生信息
    foreach (Student stu in item.Value)
    {
         //1.4班级节点的子节点：学生
         XElement stuElement = new XElement("student");
         stuElement.SetAttributeValue("sid", stu.SId);
         classElement.Add(stuElement);

         //1.5学生子节点：姓名、年龄
         XElement nameElement = new XElement("name");
         nameElement.Value = stu.Name;
         stuElement.Add(nameElement);
         XElement ageElement = new XElement("age");
         ageElement.Value = stu.Age.ToString();
         stuElement.Add(ageElement);
     }
}

//4.保存到文本文件
xDoc.Save("demo2.xml");

2、读方法

#region 1.读取xml文件(XDocument)
XDocument xDoc = XDocument.Load("demo2.xml");
//2.获取根节点
XElement rootElement = xDoc.Root;
//3.将根节点加载到TreeView上
TreeNode rootNode = treeView1.Nodes.Add(rootElement.Name.ToString());
//4.递归加载
 LoadXmlToTreeView(rootElement, rootNode.Nodes);
 #endregion

LoadXmlToTreeView()定义如下：

private void LoadXmlToTreeView(XElement rootElement, TreeNodeCollection treeNodeCollection)
{
     //获取根元素rootElement下的所有子元素（直接子元素）
     foreach (XElement item in  rootElement.Elements())
     {
          if(item.Elements().Count()==0)
          {
               TreeNode node = treeNodeCollection.Add(item.Name.ToString());
               node.Nodes.Add(item.Value.ToString());
          }
          else
          {
               TreeNode node = treeNodeCollection.Add(item.Name.ToString());
               LoadXmlToTreeView(item, node.Nodes);
         }
     }
}

四、完整源代码

1.Student.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _2Xml读写操作
{
    class Student
    {
        public Student(string name,int age,string sid)
        {
            this.Name = name;
            this.Age = age;
            this.SId = sid;
        }
        public string Name
        {
            get;
            set;
        }
        public int Age
        {
            get;
            set;
        }
        public string SId
        {
            get;
            set;
        }
    }
}

2.Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Xml;
using System.Xml.Linq;

namespace _2Xml读写操作
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 写入xml文件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            //0.全校学生信息集合
            Dictionary<string, List<Student>> allstudengts = new Dictionary<string, List<Student>>();

            List<Student> class1List = new List<Student>();
            class1List.Add(new Student("张三", 16, "c101"));
            class1List.Add(new Student("李四", 23, "c102"));
            class1List.Add(new Student("王五", 31, "c103"));
            allstudengts.Add("c100", class1List);

            List<Student> class2List = new List<Student>();
            class2List.Add(new Student("李诞", 32, "c201"));
            class2List.Add(new Student("池子", 18, "c202"));
            class2List.Add(new Student("卡姆", 29, "c203"));
            allstudengts.Add("c200", class2List);

            #region 1.【XmlDocument】方法写入xml文件
            1.1实例化xml对象，并添加文档说明信息
            //XmlDocument xml = new XmlDocument();
            //XmlDeclaration xmldeclaration = xml.CreateXmlDeclaration("1.0", "utf-8", "yes");
            //xml.AppendChild(xmldeclaration);

            1.2根节点：学校
            //XmlElement rootElement = xml.CreateElement("school");
            //xml.AppendChild(rootElement);
            依次写入各个班级学生信息
            //foreach (var item in allstudengts)
            //{
            //    //1.3根节点的子节点：班级
            //    XmlElement classElement = xml.CreateElement("class");
            //    //创建属性
            //    XmlAttribute classAttribute = xml.CreateAttribute("id");
            //    classAttribute.Value = item.Key;
            //    classElement.Attributes.Append(classAttribute);
            //    rootElement.AppendChild(classElement);
            //    //依次该班级每名学生信息
            //    foreach (Student stu in item.Value)
            //    {
            //        //1.4班级节点的子节点：学生
            //        XmlElement studentElement = xml.CreateElement("student");
            //        XmlAttribute studentAttribute = xml.CreateAttribute("sid");
            //        studentAttribute.Value = stu.SId;
            //        studentElement.Attributes.Append(studentAttribute);

            //        //1.5学生子节点：姓名、年龄
            //        XmlElement nameElement = xml.CreateElement("name");
            //        nameElement.InnerText = stu.Name;

            //        XmlElement ageElement = xml.CreateElement("age");
            //        ageElement.InnerText = stu.Age.ToString();

            //        //1.6依次插入节点到根节点
            //        classElement.AppendChild(studentElement);
            //        studentElement.AppendChild(nameElement);
            //        studentElement.AppendChild(ageElement);
            //    }
            //}

            2.写入文件(没有根节点不能写入)
            //xml.Save("demo.xml");
            #endregion

            #region 2.【XDocument】方法写入xml文件
            //1.创建dom对象
            XDocument xDoc = new XDocument();
            XDeclaration xDec = new XDeclaration("1.0", "utf-8", null);
            xDoc.Declaration = xDec;

            //2.创建根节点
            XElement rootElement = new XElement("school");
            xDoc.Add(rootElement);

            //3.循环加载学生信息
            foreach (var item in allstudengts)
            {
                //根节点的子节点：班级
                XElement classElement = new XElement("class");
                classElement.SetAttributeValue("cid", "c100");
                rootElement.Add(classElement);

                //依次该班级每名学生信息
                foreach (Student stu in item.Value)
                {
                    //1.4班级节点的子节点：学生
                    XElement stuElement = new XElement("student");
                    stuElement.SetAttributeValue("sid", stu.SId);
                    classElement.Add(stuElement);

                    //1.5学生子节点：姓名、年龄
                    XElement nameElement = new XElement("name");
                    nameElement.Value = stu.Name;
                    stuElement.Add(nameElement);
                    XElement ageElement = new XElement("age");
                    ageElement.Value = stu.Age.ToString();
                    stuElement.Add(ageElement);
                }
            }

            //4.保存到文本文件
            xDoc.Save("demo2.xml");

            #endregion

            MessageBox.Show("写入xml文件完毕!", "写xml");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            #region 1.读取xml文件(XDocument)
            //XDocument xDoc = XDocument.Load("demo2.xml");
            2.获取根节点
            //XElement rootElement = xDoc.Root;
            3.将根节点加载到TreeView上
            //TreeNode rootNode = treeView1.Nodes.Add(rootElement.Name.ToString());
            4.递归加载
            //LoadXmlToTreeView(rootElement, rootNode.Nodes);
            #endregion

            #region 2.读取xml文件(XmlDocument)
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load("demo2.xml");
            //获取根节点
            XmlElement rootElement = xmlDoc.DocumentElement;
            //将根节点加载到TreeView上
            TreeNode rootNode = treeView1.Nodes.Add(rootElement.Name);
            //递归加载
            LoadXmlByXmlDocument(rootElement, rootNode.Nodes);
            rootNode.Expand();

            #endregion
            MessageBox.Show("读取xml文件完毕!", "读xml");
        }

        //读取xml文件(XmlDocument)
        private void LoadXmlByXmlDocument(XmlElement rootElement, TreeNodeCollection treeNodeCollection)
        {
            //循环rootElement下的所有子元素（直接子元素）
            foreach (XmlNode item in rootElement.ChildNodes)
            {
                if (item.NodeType == XmlNodeType.Element)
                {
                   TreeNode node =  treeNodeCollection.Add(item.Name);
                   LoadXmlByXmlDocument((XmlElement)item, node.Nodes);
                }
                else if (item.NodeType == XmlNodeType.Text || item.NodeType == XmlNodeType.CDATA)
                {
                   treeNodeCollection.Add(item.InnerText);
                }
            }
        }

        private void LoadXmlToTreeView(XElement rootElement, TreeNodeCollection treeNodeCollection)
        {
            //获取根元素rootElement下的所有子元素（直接子元素）
            foreach (XElement item in  rootElement.Elements())
            {
                if(item.Elements().Count()==0)
                {
                    TreeNode node = treeNodeCollection.Add(item.Name.ToString());
                    node.Nodes.Add(item.Value.ToString());
                }
                else
                {
                    TreeNode node = treeNodeCollection.Add(item.Name.ToString());
                    LoadXmlToTreeView(item, node.Nodes);
                }
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            #region 1.XmlDocument
            XmlDocument document = new XmlDocument();
            //加载
            OpenFileDialog openDialog = new OpenFileDialog();
            openDialog.Filter = "XML文件(*.xml)|*.xml";
            DialogResult result = openDialog.ShowDialog();
            string path = string.Empty;
            if (result == System.Windows.Forms.DialogResult.OK)
            {
                path = openDialog.FileName;
            }
            document.Load(path);

            XmlNodeList nodeList = document.GetElementsByTagName("name");
            MessageBox.Show(nodeList.Count.ToString(), "指定name节点");
            //string msg = string.Empty;
            //foreach (XmlNode item in nodeList)
            //{
            //    msg += item.Name + " ";
                
            //}
            //MessageBox.Show(msg,"指定name节点");
            #endregion

            #region 2.XDocument
            //加载
            //OpenFileDialog openDialog = new OpenFileDialog();
            //openDialog.Filter = "XML文件(*.xml)|*.xml";
            //DialogResult result = openDialog.ShowDialog();
            //string path = string.Empty;
            //if (result == System.Windows.Forms.DialogResult.OK)
            //{
            //    path = openDialog.FileName;
            //}
            //XDocument xd = XDocument.Load(path);
            根节点
            //XElement rootElement = xd.Root;
            //XElement nameXElement = rootElement.Element("name");
            //IEnumerable<XElement> ie = rootElement.Descendants("class");
            //MessageBox.Show(path);
            #endregion
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
    }
}