XmlHelper操作类

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

namespace Tools
{
    public class XmlHelper
    { 
        #region 字段定义
        /// <summary>
        /// XML文件的物理路径
        /// </summary>
        private string _filePath = string.Empty;
        /// <summary>
        /// Xml文档
        /// </summary>
        private XmlDocument _xml;
        /// <summary>
        /// XML的根节点
        /// </summary>
        private XmlElement _element;
        #endregion

        #region 构造方法
        /// <summary>
        /// 实例化XmlHelper对象

        /// </summary>
        /// <param name="xmlFilePath">Xml文件的相对路径</param>
        public XmlHelper(string xmlFilePath)
        {
            //获取XML文件的绝对路径
            //_filePath = SysHelper.GetPath(xmlFilePath);
            _filePath = xmlFilePath;
        }
        #endregion

        #region 创建XML的根节点
        /// <summary>
        /// 创建XML的根节点
        /// </summary>
        private void CreateXMLElement()
        {
            //创建一个XML对象
            _xml = new XmlDocument();
            if(File.Exists(_filePath))
            {
                //加载XML文件
                _xml.Load(this._filePath);
            }
            //为XML的根节点赋值
            _element = _xml.DocumentElement;
        }
        #endregion

        #region 获取指定XPath表达式的节点对象
        /// <summary>