asp.net操作xml实现创建，添加，删除，...

添加用户：
private void btnAdd_Click(object sender, System.EventArgs e)
        {
            string uID = txtUID.Text;
            string userName = txtUserName.Text;
            string City = txtCity.Text;
            string Email = txtEmail.Text;
            if(!System.IO.File.Exists(xmlFile))
            {
                lblMsg.Text = "xml文件"+xmlFile+"不存在，请先点击创建！";
                return;
            }
            XmlDocument xmlDoc                = new XmlDocument();
            xmlDoc.Load(xmlFile);    //加载文件
            XmlNode root                    = xmlDoc.SelectSingleNode("dbGuest");//查找<dbGuest>
            XmlElement xe_dbGuest_User        = xmlDoc.CreateElement("User");//创建一个<User>节点
            XmlElement xe_dbGuest_User_Name    = xmlDoc.CreateElement("Name");
            xe_dbGuest_User_Name.InnerText    = userName;//设置文本节点         
            XmlAttribute a                    = xmlDoc.CreateAttribute("uid");//创建一个 属性
            a.Value                            = uID;
            xe_dbGuest_User_Name.Attributes.Append(a);//增加一个属性
            xe_dbGuest_User.AppendChild(xe_dbGuest_User_Name);//添加到<User>节点中
            XmlElement xe_dbGuest_User_City    = xmlDoc.CreateElement("City");//创建City节点
            xe_dbGuest_User_City.InnerText    = City;
            xe_dbGuest_User.AppendChild(xe_dbGuest_User_City);//添加到<User>节点中
            XmlElement xe_dbGuest_User_Email    = xmlDoc.CreateElement("Email");//创建Email节点
            xe_dbGuest_User_Email.InnerText    = Email;
            xe_dbGuest_User.AppendChild(xe_dbGuest_User_Email);
            root.AppendChild(xe_dbGuest_User);//添加到<dbGuest>节点中
            xmlDoc.Save(xmlFile);//保存文件
            lblMsg.Text = "成功添加用户";
            GetXmlContent();
            BindXML();
            BindUserNames();
        }
//绑定xml数据
        private void BindXML()
        {
            if(!System.IO.File.Exists(xmlFile))
            {
                lblMsg.Text = "xml文件"+xmlFile+"不存在，请先点击创建！";
                return;
            }
//            方法一：通过ds 读取 xml
//            DataSet ds = new DataSet();
//            ds.ReadXml(xmlFile);
//            if(ds.Tables.Count > 0)
//            {
//                dgValue.DataSource = ds.Tables[0].DefaultView;
//                dgValue.DataBind();
//            }
            //方法二
            DataTable dt = new DataTable();
            DataColumn dc = new DataColumn("uid");
            dt.Columns.Add(dc);            
            dc = new DataColumn("name");
            dt.Columns.Add(dc);
            dc = new DataColumn("city");
            dt.Columns.Add(dc);
            dc = new DataColumn("email");
            dt.Columns.Add(dc);     
            //将xml文件加载成xmlDoc
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(xmlFile);
            //得到dbGust所有子节点
            XmlNodeList xnl=xmlDoc.SelectSingleNode("dbGuest").ChildNodes;             
            for(int i = 0 ; i < xnl.Count;i++)
            {
                //在每个子节点是遍历    xn 代表的是一个个User
                string uid = xnl.Item(i).ChildNodes[0].Attributes["uid"].Value;
                string name = xnl.Item(i).ChildNodes[0].InnerText;
                string city = xnl.Item(i).ChildNodes[1].InnerText;
                string email = xnl.Item(i).ChildNodes[2].InnerText;
                DataRow dr = dt.NewRow();
                dr[0] = uid;
                dr[1] = name;
                dr[2] = city;
                dr[3] = email;
                dt.Rows.Add(dr);                
            }
            dgValue.DataSource = dt;
            dgValue.DataBind();             
        }

删除用户：
private void btnDelete_Click(object sender, System.EventArgs e)
        {
            string selectName = ddlNames.SelectedItem.Text;
            string selectID = ddlNames.SelectedValue;
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(xmlFile);
            XmlNodeList xnl=xmlDoc.SelectSingleNode("dbGuest").ChildNodes;             
            for(int i = 0 ; i < xnl.Count ; i++)
            {
                XmlElement xe=(XmlElement)xnl[i];//第i个dbGust子节点
                XmlNodeList node = xe.GetElementsByTagName("Name");
                if(node.Count>0)
                {
                    //判断为用户选择的
                    if(node[0].InnerText==selectName && node[0].Attributes["uid"].Value == selectID)
                    {
                        string m = node[0].InnerText;
                        xmlDoc.SelectSingleNode("dbGuest").RemoveChild(node[0].ParentNode);//删除该User节点    
                        //xe.RemoveAll();//删除该节点的全部内容 这二种有差别
                        
                        break;
                        
                    }
                    
                }
            }                      
            xmlDoc.Save(xmlFile);
            BindXML();
            GetXmlContent();
            BindUserNames();
        }

更新用户：
private void btnUpdate_Click(object sender, System.EventArgs e)
        {
            string selectName = ddlNames.SelectedItem.Text;
            string selectID = ddlNames.SelectedValue;
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(xmlFile);
            XmlNodeList nodeList=xmlDoc.SelectSingleNode("dbGuest").ChildNodes;//获取dbGuest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
            
                XmlNodeList node = xe.GetElementsByTagName("Name");
                if(node.Count>0)
                {
                    //判断为用户选择的
                    if(node[0].InnerText==selectName && node[0].Attributes["uid"].Value == selectID)
                    {
                        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=="Email")//如果找到Email属性
                            {
                                xe2.InnerText="http://eflylab.cnblogs.com";//则修改
                                break;//找到退出来就可以了
                            }
                        }
                        break;
                    }
                }
                
            }
            xmlDoc.Save(xmlFile);
            BindXML();
            GetXmlContent();
        }

查询用户：
private void btnSelect_Click(object sender, System.EventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load(xmlFile);
            string selectName = ddlNames.SelectedItem.Text;
            string email = doc.SelectSingleNode("//User[Name=’"+selectName+"’]").ChildNodes.Item(2).InnerText;         
            
            lblMsg.Text = "查询"+selectName+"用户email为"+email;
        }