XML Read And write

 public abstract class DocBase
    {
        protected String fileName = "";
        protected XmlNode node = null;

        public XmlDocument xmlDoc;
        public int count;

        public virtual void read()
        {

        }

        public virtual void add()
        {

        }

        protected void save(XmlDocument doc)
        {
            XmlTextWriter writer = new XmlTextWriter(fileName, null);
            writer.Formatting = Formatting.Indented;
            doc.WriteTo(writer);
            writer.Flush();
            writer.Close();
        }
    }

using System;
using System.Collections.Generic;
using System.Text;
using System.Xml;

namespace Lib
{

    public class DocScreen : DocBase
    {
        public DocScreen(String File)
        {
            fileName = File;
            xmlDoc = new XmlDocument();
            xmlDoc.Load(File);
            count = 0;

        }


        public Screens[] readAll()
        {

            Screens[] all = new Screens[10000];
            XmlNode xn = xmlDoc.SelectSingleNode("Config");//查找
            XmlNodeList xnl = xn.ChildNodes;
            //XmlElement xe1=xmlDoc.GetElementsByTagName("CameraController");
            foreach (XmlNode xnf in xnl)
            {
                // XmlElement xe = (XmlElement)xnf;
                if (xnf.Name == "Screens")
                {
                    XmlNodeList xnl2 = xnf.ChildNodes;
                    foreach (XmlNode xnf2 in xnl2)
                    {
                        XmlElement xe = (XmlElement)xnf2;

                        all[count].PatrolIP = xe.GetAttribute("PatrolIP").Split(',');//显示属性值
                        all[count].PatroTime = xe.GetAttribute("PatroTime");
                        all[count].ScreenIndex = xe.GetAttribute("ScreenIndex");
                        all[count].ScreenMode = xe.GetAttribute("ScreenMode");
                        all[count].Title = xe.GetAttribute("Title");                       
                        //all[count].NetGate = "";
                        //all[count].NetMask = "";
                        //all[count].Runtime = "";
                        //all[count].VideoType = "";

                        count = count + 1;
                    }
                    break;

                }

            }

            return all;
        }


        public Screens read(String ScreenMode, String ScreenIndex)
        {
            Screens[] all;
            Screens r = new Screens();
            all = this.readAll();
            for (int i = 0; i < count; i++)
            {
                if (all[i].ScreenMode == ScreenMode && all[i].ScreenIndex == ScreenIndex)
                {
                    r = all[i];
                    break;

                }

            }
            return r;

        }


        public bool add(ScreenDetailInfo sreenDetailInfo)
        {
            try
            {
                node = xmlDoc.SelectSingleNode("//Config");
                if (node != null)
                {
                    XmlElement addElem = (XmlElement)node.SelectSingleNode("//Screens");
                    if (addElem == null)
                    {
                        XmlElement ScreenCofig = xmlDoc.CreateElement("Screens");
                        node.AppendChild(ScreenCofig);
                    }
                    node = xmlDoc.SelectSingleNode("//Screens");

                    XmlElement temp = (XmlElement)xmlDoc.SelectSingleNode("//Screen[@ScreenMode='" + sreenDetailInfo.ScreenMode + "'][@ScreenIndex='" + sreenDetailInfo.ScreenIndex + "']");
                    if (temp != null)
                    {
                        node.RemoveChild(temp);
                    }

                    XmlElement first = xmlDoc.CreateElement("Screen");
                    first.SetAttribute("ScreenMode", sreenDetailInfo.ScreenMode);
                    first.SetAttribute("ScreenIndex", sreenDetailInfo.ScreenIndex);
                    first.SetAttribute("PatroTime", sreenDetailInfo.PatroTime);
                    first.SetAttribute("Title", sreenDetailInfo.Title);
                    first.SetAttribute("PatrolIP", sreenDetailInfo.PatrolIP);
                    node.AppendChild(first);
                    save(xmlDoc);
                }
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Write Screen Detail Info Error: " + ex.ToString());
                return false;
            }
        }

    }
}