C#读写XML

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

namespace AutoRunMgr
{
    public class XML
    {
        public static void CreateNode(string xmlpath,string node,string value)
        {
            if (!File.Exists(xmlpath))
            {
                XmlDocument xmlDoc = new XmlDocument();
                XmlElement root = xmlDoc.CreateElement("setting");
                XmlElement child = xmlDoc.CreateElement(node);
                child.InnerText = value;
                root.AppendChild(child);
                xmlDoc.AppendChild(root);
                xmlDoc.Save(@"setting.xml");
            }
            else
            {
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(xmlpath);
                XmlNode root = xmlDoc.DocumentElement;
                XmlNode child = root.SelectSingleNode(node);
                if (child == null)
                {
                    child=xmlDoc.CreateElement(node);
                }
                child.InnerText = value;                    
                root.AppendChild(child);
                xmlDoc.AppendChild(root);
                xmlDoc.Save(@"setting.xml");
            }
        }
        public static string ReadNode(string xmlpath, string node)
        {
            if (File.Exists(xmlpath))
            {
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(xmlpath);
                XmlElement root = xmlDoc.DocumentElement;
                XmlNode child = root.SelectSingleNode(node);//查找<node>

                return (child == null) ? "" : child.InnerText;
            }
            else
            {
                return "";
            }
        }
    }
}