C#中XML文件读写

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


namespace XMLDocumentTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
　　    　　InitializeComponent();
        }

        private void DelElementTest()
        {
            XmlDocument doc = new XmlDocument();
            XmlReaderSettings settings = new XmlReaderSettings();
            settings.IgnoreComments = true;
            XmlReader xmlreader = XmlReader.Create("Book.xml", settings);
            doc.Load(xmlreader);
            xmlreader.Close();

            if (dataGridView1.SelectedRows.Count <= 0)
                return;
            string ISBN = dataGridView1.SelectedRows[0].Cells[1].Value.ToString();
            string path = string.Format("/bookstore/book[@ISBN="{0}"]", ISBN);
            XmlElement element = (XmlElement)doc.SelectSingleNode(path);
            if (element != null)
            {
                element.ParentNode.RemoveChild(element);
            }
        }

            XmlDocument doc = new XmlDocument();
            private new void Load(object sender, EventArgs e)
            {
                  List<BookModel> bookmodelList = new List<BookModel>(); ;
                  XmlReaderSettings settings = new XmlReaderSettings();
                  settings.IgnoreComments = true;
                  XmlReader xmlreader = XmlReader.Create("Book.xml", settings);
                  doc.Load(xmlreader);
                  xmlreader.Close();
                  XmlNode root = doc.SelectSingleNode("bookstore");
                  XmlNodeList nodelist = root.ChildNodes;
                  foreach (XmlNode node in nodelist)
                  {
                        BookModel bookmodel = new BookModel();
                        XmlElement element = (XmlElement)node;
                        bookmodel.BookType = element.GetAttribute("Type");
                        bookmodel.BookISBN = element.GetAttribute("ISBN");
                        XmlNodeList children = element.ChildNodes;
                        bookmodel.BookName = children[0].InnerText;
                        bookmodel.BookAuthor = children[1].InnerText;
                        bookmodel.BookPrice = Convert.ToDouble(children[2].InnerText);

                        bookmodelList.Add(bookmodel);

                  }
                  dataGridView1.DataSource = bookmodelList;
            }

            private void AddBook(object sender, EventArgs e)
            {
                  XmlReaderSettings settings = new XmlReaderSettings();
                  settings.IgnoreComments = true;
                  XmlReader xmlreader = XmlReader.Create("Book.xml", settings);
                 doc.Load(xmlreader);
                  xmlreader.Close();
                  XmlNode root = doc.SelectSingleNode("bookstore");

                  XmlElement element = doc.CreateElement("book");
                  XmlAttribute attribute = doc.CreateAttribute("Type");
                  attribute.InnerText = "必修课";
                  element.SetAttributeNode(attribute);
                  attribute = doc.CreateAttribute("ISBN");
                  attribute.InnerText = "7-111-19149-4";
                  element.SetAttributeNode(attribute);

                  XmlElement childElement = doc.CreateElement("Title");
                  childElement.InnerText = "分布式框架";
                  element.AppendChild(childElement);
                  childElement = doc.CreateElement("Author");
                  childElement.InnerText = "brian";
                  element.AppendChild(childElement);
                  childElement = doc.CreateElement("Price");
                  childElement.InnerText = "250";
                  element.AppendChild(childElement);

                  root.AppendChild(element);
                  doc.Save("Book.xml");
                  Load(null, null);
                  dataGridView1.ClearSelection();
            }

            private void Del(object sender, EventArgs e)
            {
                  XmlReaderSettings settings = new XmlReaderSettings();
                  settings.IgnoreComments = true;
                  XmlReader xmlreader = XmlReader.Create("Book.xml", settings);
                  doc.Load(xmlreader);
                  xmlreader.Close();


                  if (dataGridView1.SelectedCells.Count <= 0)
                      return;
                  int selectedRowIndex = dataGridView1.SelectedCells[0].RowIndex;
                  string ISBN = dataGridView1.Rows[selectedRowIndex].Cells[1].Value.ToString();
                  string path = string.Format("/bookstore/book[@ISBN="{0}"]",ISBN);
                  XmlElement element = (XmlElement)doc.SelectSingleNode(path);
                  if (element != null)
                  {
                       element.ParentNode.RemoveChild(element);
                  }
                  doc.Save("Book.xml");
                  Load(null, null);
                  dataGridView1.ClearSelection();
                  }

            private void button4_Click(object sender, EventArgs e)
            {
                  this.dataGridView1.DataSource = null;
            }
       }
}