using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Xml;
private XmlDocument xmlDoc;

        //load xml file
        private void LoadXml()
        {
            xmlDoc=new XmlDocument();
            xmlDoc.Load(Server.MapPath("User.xml"));
        }

        //添加节点
        private void AddElement()
        {
           
            LoadXml();

            XmlNode xmldocSelect=xmlDoc.SelectSingleNode("user");
           
            XmlElement el=xmlDoc.CreateElement("person"); //添加person节点
            el.SetAttribute("name","风云"); //添加person节点的属性"name"
            el.SetAttribute("sex","女");   //添加person节点的属性 "sex"
            el.SetAttribute("age","25");   //添加person节点的属性 "age"
           
             XmlElement xesub1=xmlDoc.CreateElement("pass"); //添加person节点的里的节点
             xesub1.InnerText="123";//设置文本节点
             el.AppendChild(xesub1);
             XmlElement xesub2=xmlDoc.CreateElement("Address");
             xesub2.InnerText="昆明";//设置文本节点
             el.AppendChild(xesub2);

            xmldocSelect.AppendChild(el);
            xmlDoc.Save(Server.MapPath("user.xml"));

        }

        //修改节点
        private void UpdateElement()
        {
            LoadXml();
            XmlNodeList nodeList=xmlDoc.SelectSingleNode("user").ChildNodes;//获取bookstore节点的所有子节点
            foreach(XmlNode xn in nodeList)//遍历所有子节点
            {
                XmlElement xe=(XmlElement)xn;//将子节点类型转换为XmlElement类型
                if(xe.GetAttribute("name")=="风云")//如果name属性值为“风云”
                {
                    xe.SetAttribute("name","发明");

                   
                    //如果下面有子节点在下走
                     XmlNodeList nls=xe.ChildNodes;//继续获取xe子节点的所有子节点
                    foreach(XmlNode xn1 in nls)//遍历
                    {
                       XmlElement xe2=(XmlElement)xn1;//转换类型
                        if(xe2.Name=="pass")//如果找到
                        {
                            xe2.InnerText="66666";//则修改
                            break;

                        }
                    }

                    break;
                }
            }
           xmlDoc.Save(Server.MapPath("user.xml"));//保存
        }

        //删出节点
        private void deleteNode()
        {
           
            LoadXml();
            XmlNodeList xnl=xmlDoc.SelectSingleNode("user").ChildNodes;
 
            foreach(XmlNode xn in xnl)
            {
                XmlElement xe=(XmlElement)xn;
               
                if(xe.GetAttribute("name")=="发明")
                {
                    //xe.RemoveAttribute("name");//删除name属性
                   // xe.RemoveAll();//删除该节点的全部内容
                    xe.ParentNode.RemoveChild(xe);
                   
                    break;
                }
               
            }
            xmlDoc.Save(Server.MapPath("user.xml"));//保存
        }

        private void showIt()
        {
            LoadXml();
            XmlNode xn=xmlDoc.SelectSingleNode("user");
 
            XmlNodeList xnl=xn.ChildNodes;
  
            foreach(XmlNode xnf in xnl)
            {
                XmlElement xe=(XmlElement)xnf;
//                Console.WriteLine(xe.GetAttribute("name"));//显示属性值
//                Console.WriteLine(xe.GetAttribute("sex"));
//
//                XmlNodeList xnf1=xe.ChildNodes;
//                foreach(XmlNode xn2 in xnf1)
//                {
//                    Console.WriteLine(xn2.InnerText);//显示子节点点文本
//                }

            }

        }
   
Xml的样式:

<?xml version="1.0" encoding="gb2312"?>
<user>
  <person>
  </person>
  <person name="风拉" sex="男" age="25">
    <pass>123</pass>
    <Address>大明</Address>
  </person>
  <person name="风云" sex="女" age="25">
    <pass>123</pass>
    <Address>昆明</Address>
  </person>
</user>