Linq to xml实现xml数据增删改查

Contact.cs类:

 public class Contact    {        public int Id { get; set; }        public string FirstName { get; set; }        public string LastName { get; set; }        public string Company { get; set; }        public string City { get; set; }        public string Telephone { get; set; }        public string Fax { get; set; }        public string Email { get; set; }    }

LinqXmlContactsBLManager.cs

using System.Collections.Generic;using System.IO;using System.Linq;using System.Xml.Linq;namespace LinqXmlContactsBLL{    public class LinqXmlContactsBLManager    {        public List<Contact> GetAllContacts()        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            IEnumerable<XElement> xmlContacts = xmlDocument.Element("Contacts")                .Elements("Contact");            List<Contact> contacts = new List<Contact>();            //获取联系人列表            foreach (XElement i in xmlContacts)            {                Contact contact = new Contact();                contact.Id = int.Parse(i.Attribute("Id").Value);                contact.FirstName = i.Element("FirstName").Value;                contact.LastName = i.Element("LastName").Value;                contact.Company = i.Element("Company").Value;                contact.City = i.Element("City").Value;                contact.Telephone = i.Element("Telephone").Value;                contact.Fax = i.Element("Fax").Value;                contact.Email = i.Element("Email").Value;                contacts.Add(contact);            }            return contacts;        }        public Contact GetContactById(int id)        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            XElement xmlContact = xmlDocument.Element("Contacts").Elements("Contact")                .Where(a => a.Attribute("Id").Value == id.ToString()).FirstOrDefault();            Contact contact = new Contact();            contact.Id = int.Parse(xmlContact.Attribute("Id").Value);            contact.FirstName = xmlContact.Element("FirstName").Value;            contact.LastName = xmlContact.Element("LastName").Value;            contact.Company = xmlContact.Element("Company").Value;            contact.City = xmlContact.Element("City").Value;            contact.Telephone = xmlContact.Element("Telephone").Value;            contact.Fax = xmlContact.Element("Fax").Value;            contact.Email = xmlContact.Element("Email").Value;            return contact;        }        public void AddContact(Contact contact)        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            //将值插入联系人xml文档            xmlDocument.Element("Contacts").Add(                new XElement("Contact",                    new XAttribute("Id", contact.Id),                    new XElement("FirstName", contact.FirstName),                    new XElement("LastName", contact.LastName),                    new XElement("Company", contact.Company),                    new XElement("City", contact.City),                    new XElement("Telephone", contact.Telephone),                    new XElement("Fax", contact.Fax),                    new XElement("Email", contact.Email)                    ));            xmlDocument.Save("Contacts.xml");        }        public void UpdateContact(Contact contact)        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            //通过ID更新联系人            XElement xmlContact = xmlDocument.Element("Contacts").Elements("Contact")                .Where(x => x.Attribute("Id").Value == contact.Id.ToString())                .FirstOrDefault();            //更新联系人            xmlContact.SetElementValue("FirstName", contact.FirstName);            xmlContact.SetElementValue("LastName", contact.LastName);            xmlContact.SetElementValue("Company", contact.Company);            xmlContact.SetElementValue("City", contact.City);            xmlContact.SetElementValue("Telephone", contact.Telephone);            xmlContact.SetElementValue("Fax", contact.Fax);            xmlContact.SetElementValue("Email", contact.Email);            xmlDocument.Save("Contacts.xml");        }        public void DeleteContact(int id)        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            //得到联系人并删除他            xmlDocument.Root.Elements().Where(x => x.Attribute("Id").Value == id.ToString())                .FirstOrDefault().Remove();            xmlDocument.Save("Contacts.xml");        }        public int GetNextId()        {            int currentId;            XDocument xmlDocument = XDocument.Load("Contacts.xml");            //获取id的集合            IEnumerable<int> contactIds = xmlDocument.Element("Contacts").Elements("Contact")                .Select(x => int.Parse(x.Attribute("Id").Value));            //如果集合为空，则将变量设置为0，否则将该变量设置为最高ID值            if (contactIds.Count() == 0)                currentId = 0;            else                currentId = contactIds.Max();            return currentId + 1;        }        public void SetXmlFile()        {            //如果xml文件丢失，则使用根元素创建它            if (!(File.Exists("Contacts.xml")))            {                XDocument xmlDocument = new XDocument(                    new XDeclaration("1.0", "utf-8", "yes"),                    new XElement("Contacts"));                xmlDocument.Save("Contacts.xml");            }        }        public bool IdExists(int id)        {            XDocument xmlDocument = XDocument.Load("Contacts.xml");            return xmlDocument.Element("Contacts").Elements("Contact")                .Select(x => int.Parse(x.Attribute("Id").Value))                .Where(y => y == id).Count() > 0;        }    }}

主窗体frmMain.cs

  public partial class frmMain : Form    {        LinqXmlContactsBLManager blManager = new LinqXmlContactsBLManager();        public frmMain()        {            InitializeComponent();            //如果xml文件丢失，创建它            blManager.SetXmlFile();            dataGridView1.DataSource = blManager.GetAllContacts();        }        private void btnViewContact_Click(object sender, EventArgs e)        {            if (txtId.Text == "")            {                MessageBox.Show("请输入ID", "消息");                txtId.Focus();                return;            }            int x;            if (!int.TryParse(txtId.Text, out x))            {                MessageBox.Show("请输入有效的ID", "消息");                txtId.Focus();                txtId.SelectAll();                return;            }            if (!blManager.IdExists(int.Parse(txtId.Text)))            {                MessageBox.Show("id " + txtId.Text + " 不存在", "消息");                txtId.Focus();                txtId.SelectAll();                return;            }            //通过id获得一个联系人            Contact contact = blManager.GetContactById(int.Parse(txtId.Text));            //show the contact properties on the controls            lblId.Text = contact.Id.ToString();            txtFirstName.Text = contact.FirstName;            txtLastName.Text = contact.LastName;            txtCompany.Text = contact.Company;            txtCity.Text = contact.City;            txtTelephone.Text = contact.Telephone;            txtFax.Text = contact.Fax;            txtEmail.Text = contact.Email;            txtId.Clear();        }        private void btnNewContact_Click(object sender, EventArgs e)        {            frmAdd frmAdd1 = new frmAdd();            frmAdd1.ShowDialog();            dataGridView1.DataSource = blManager.GetAllContacts();        }        private void btnUpdateContact_Click(object sender, EventArgs e)        {            if (lblId.Text == "")            {                MessageBox.Show("未选择联系人", "消息");                txtId.Focus();                txtId.SelectAll();                return;            }            if (txtFirstName.Text == "")            {                MessageBox.Show("请输入姓氏", "消息");                txtFirstName.Focus();                return;            }            if (txtLastName.Text == "")            {                MessageBox.Show("请输入名", "消息");                txtLastName.Focus();                return;            }            if (txtCompany.Text == "")            {                MessageBox.Show("请输入公司", "消息");                txtCompany.Focus();                return;            }            if (txtCity.Text == "")            {                MessageBox.Show("请输入城市", "消息");                txtCity.Focus();                return;            }            if (txtTelephone.Text == "")            {                MessageBox.Show("请输入电话", "消息");                txtTelephone.Focus();                return;            }            if (txtFax.Text == "")            {                MessageBox.Show("请输入传真", "消息");                txtFax.Focus();                return;            }            if (txtEmail.Text == "")            {                MessageBox.Show("请输入邮件", "消息");                txtEmail.Focus();                return;            }            //创建一个联系人，并从控件值设置他的属性            Contact contact = new Contact()            {                Id = int.Parse(lblId.Text),                FirstName = txtFirstName.Text,                LastName = txtLastName.Text,                Company = txtCompany.Text,                City = txtCity.Text,                Telephone = txtTelephone.Text,                Fax = txtFax.Text,                Email = txtEmail.Text            };            //更新联系人            blManager.UpdateContact(contact);            dataGridView1.DataSource = blManager.GetAllContacts();        }        private void btnDeleteContact_Click(object sender, EventArgs e)        {            if (lblId.Text == "")            {                MessageBox.Show("未选择联系人", "消息");                txtId.Focus();                txtId.SelectAll();                return;            }            Contact contact = blManager.GetContactById(int.Parse(lblId.Text));            string messageToPrint = "The following contact will get deleted:\n\n" +                "Id : " + contact.Id.ToString() + "\n" +                "First name : " + contact.FirstName + "\n" +                "Last name : " + contact.LastName + "\n" +                "Company : " + contact.Company + "\n" +                "City : " + contact.City + "\n" +                "Telephone : " + contact.Telephone + "\n" +                "Fax : " + contact.Fax + "\n" +                "Email : " + contact.Email + "\n\n" +                "Are you sure?";            DialogResult dialogResult = MessageBox.Show(messageToPrint, "Message",                 MessageBoxButtons.YesNo);            //如果用户点击“否”，则取消删除操作            if (dialogResult == DialogResult.No)            {                MessageBox.Show("操作被取消", "消息");                return;            }            //如果用户点击“是”，删除联系人            blManager.DeleteContact(contact.Id);            dataGridView1.DataSource = blManager.GetAllContacts();            //清除控件值            lblId.Text = "";            txtFirstName.Clear();            txtLastName.Clear();            txtCompany.Clear();            txtCity.Clear();            txtTelephone.Clear();            txtFax.Clear();            txtEmail.Clear();        }        private void btnClose_Click(object sender, EventArgs e)        {            Application.Exit();        }    }

增加窗体frmAdd.cs

  public partial class frmAdd : Form    {        LinqXmlContactsBLManager blManager = new LinqXmlContactsBLManager();        public frmAdd()        {            InitializeComponent();        }        private void btnAdd_Click(object sender, EventArgs e)        {            if (txtFirstName.Text == "")            {                MessageBox.Show("请输入姓氏", "消息");                txtFirstName.Focus();                return;            }            if (txtLastName.Text == "")            {                MessageBox.Show("请输入名字", "消息");                txtLastName.Focus();                return;            }            if (txtCompany.Text == "")            {                MessageBox.Show("请输入公司", "消息");                txtCompany.Focus();                return;            }            if (txtCity.Text == "")            {                MessageBox.Show("请输入城市", "消息");                txtCity.Focus();                return;            }            if (txtTelephone.Text == "")            {                MessageBox.Show("请输入电话", "消息");                txtTelephone.Focus();                return;            }            if (txtFax.Text == "")            {                MessageBox.Show("请输入传真", "消息");                txtFax.Focus();                return;            }            if (txtEmail.Text == "")            {                MessageBox.Show("请输入电子邮件", "消息");                txtEmail.Focus();                return;            }            //创建联系人,并从控件中为属性设置值            int id = blManager.GetNextId();            Contact contact = new Contact()            {                Id = id,                FirstName = txtFirstName.Text,                LastName = txtLastName.Text,                Company = txtCompany.Text,                City = txtCity.Text,                Telephone = txtTelephone.Text,                Fax = txtFax.Text,                Email = txtEmail.Text            };            //添加联系人            blManager.AddContact(contact);            //清除控件值            txtFirstName.Clear();            txtLastName.Clear();            txtCompany.Clear();            txtCity.Clear();            txtTelephone.Clear();            txtFax.Clear();            txtEmail.Clear();            txtFirstName.Focus();        }        private void btnClose_Click(object sender, EventArgs e)        {            Close();        }    }

运行结果如图:

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