C# winform xml的增删改查

代码如下：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Windows.Forms;
using System.Xml.Linq;

namespace XMLAction
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 从xml加载用户
        /// </summary>
        /// <param name="dgv">DataGridView</param>
        private void LoadUserData(DataGridView dgv)
        {
            //加载xml文件
            XDocument xDoc = XDocument.Load("UserData.xml");
            //获取根节点
            XElement root = xDoc.Root;
            List<User> list = new List<User>();
            //循环加载用户
            foreach (XElement item in root.Elements("user"))
            {
                User model = new User(item.Attribute("id").Value.ToString(), 
                    item.Element("name").Value.ToString(), 
                    item.Element("pwd").Value.ToString());
                list.Add(model);
            }
            dgv.DataSource = list;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            if (!System.IO.File.Exists(Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location),"UserData.xml")))//Directory.GetCurrentDirectory(), "UserData.xml")))
            {
                //MessageBox.Show("程序第一次运行,请先使用[CreateXML.exe]程序完成环境配置");
                //Application.Exit();
                //创建xml对象
                XDocument xDoc = new XDocument();
                //创建根节点
                XElement root = new XElement("Users");
                //添加根节点
                xDoc.Add(root);
                //保存xml文件
                xDoc.Save("UserData.xml");
            }
            dataGridView1.MultiSelect = false;//取消多行
            dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;//选中整行
            txtUId.ReadOnly = true;//修改时Id是不可变的
            LoadUserData(dataGridView1);
        }

        private void btnRegister_Click(object sender, EventArgs e)
        {
            string id = txtRId.Text.Trim();
            string name = txtRName.Text.Trim();
            string pwd = txtRPwd.Text;
            if (string.IsNullOrEmpty(id) || string.IsNullOrEmpty(name) || string.IsNullOrEmpty(pwd))
            {
                MessageBox.Show("请填写注册信息");
                return;
            }
            //加载xml
            XDocument xDoc = XDocument.Load("UserData.xml");
            //获取根节点
            XElement root = xDoc.Root;
            //搜索当前注册用户ID是否存在
            XElement isHaveUser = root.Elements("user").SingleOrDefault(p => p.Attribute("id").Value.ToString() == id);
            if (isHaveUser == null)
            {
                //创建user节点对象
                XElement userElement = new XElement("user");
                userElement.SetAttributeValue("id", id);
                //增加两个子节点
                userElement.SetElementValue("name", name);
                userElement.SetElementValue("pwd", pwd);
                //保存user节点
                root.Add(userElement);
                xDoc.Save("UserData.xml");
                MessageBox.Show("成功!注册用户ID为【" + id + "】");
                LoadUserData(dataGridView1);
            }
            else
            {
                MessageBox.Show("用户ID【" + id + "】已存在");
            }
        }

        //双击DataGridView控件就刷新一次数据
        private void dataGridView1_DoubleClick(object sender, EventArgs e)
        {
            LoadUserData(dataGridView1);
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("确认删除?", "操作提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == System.Windows.Forms.DialogResult.Yes)
            {
                string id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
                //加载xml
                XDocument xDoc = XDocument.Load("UserData.xml");
                //获取根节点
                XElement root = xDoc.Root;
                try
                {
                    //获取这个节点
                    XElement userElement = root.Elements("user").Where(p => p.Attribute("id").Value.ToString() == id).Single();
                    //删除这个节点
                    userElement.Remove();
                    //保存操作后的xml文件
                    xDoc.Save("UserData.xml");
                    MessageBox.Show("删除成功");
                    //加载数据
                    LoadUserData(dataGridView1);
                }
                catch(Exception ex)
                {
                    MessageBox.Show("删除失败,请刷新后重试:"+ex.Message);
                }
            }
            else
                MessageBox.Show("未删除");
        }

        //DataGridView行焦点改变
        private void dataGridView1_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            string id = dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString();
            string name = dataGridView1.Rows[e.RowIndex].Cells[1].Value.ToString();
            string pwd = dataGridView1.Rows[e.RowIndex].Cells[2].Value.ToString();
            txtUId.Text = id;
            txtUName.Text = name;
            txtUPwd.Text = pwd;
        }

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            string id = txtUId.Text.Trim();
            string name = txtUName.Text.Trim();
            string pwd = txtUPwd.Text;
            //加载xml文件
            XDocument xDoc = XDocument.Load("UserData.xml");
            //获取根节点
            XElement root = xDoc.Root;
            //找到要修改的用户
            try
            {
                XElement crrentElement = root.Elements("user").Where(p => p.Attribute("id").Value.ToString() == id).Single();
                crrentElement.SetElementValue("name", name);
                crrentElement.SetElementValue("pwd", pwd);
                //完成修改操作后，保存xml文件
                xDoc.Save("UserData.xml");
                MessageBox.Show("修改成功");
                LoadUserData(dataGridView1);
            }
            catch
            {
                MessageBox.Show("修改失败,请刷新后重试");
            }
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            string id = txtLId.Text.Trim();
            string pwd = txtLPwd.Text;
            if (string.IsNullOrEmpty(id) || string.IsNullOrEmpty(pwd))
            {
                MessageBox.Show("请填写用户Id和密码");
                return;
            }
            //加载xml文件
            XDocument xDoc = XDocument.Load("UserData.xml");
            //获取根节点
            XElement root = xDoc.Root;
            try
            {
                XElement user = root.Elements("user").Where(p => p.Attribute("id").Value.ToString() == id).Single();
                if (user.Element("pwd").Value.ToString() == pwd)
                    MessageBox.Show("登录成功");
                else
                    MessageBox.Show("密码错误");
            }
            catch
            {
                MessageBox.Show("用户不存在");
            }

        }

    }

    public class User
    {
        public User(string id, string name, string pwd)
        {
            this.Id = id;
            this.Name = name;
            this.Pwd = pwd;
        }
        public string Id { get; set; }
        public string Name { get; set; }
        public string Pwd { get; set; }
    }

}