关于XML文档操作类

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

 namespace ZW.ClassLibrary
 {
    public class XmlHelpers
     {
        /// <summary>
        /// XML文档
        /// </summary>
        XmlDocument xd = new XmlDocument();

        /// <summary>
        /// 从文件中获取XmlDocument对象
        /// </summary>
        /// <param name="file">xml文档</param>
        /// <param name="type">文档类型</param>
        public XmlHelpers(string file, string type)
        {
            if (type == "path")
            {
                XmlTextReader xr = new XmlTextReader(file);
                xd.Load(xr);
                xr.Close();
            }

            if (type == "text")
            {
                xd.LoadXml(file);
            }
        }

        /// <summary>
        /// 获取第一个匹配节点的属性值
        /// </summary>
        /// <param name="nodePath"></param>
        /// <param name="attrName"></param>
        /// <returns></returns>
        public string GetAttribute(string nodePath, string attrName)
        {
            XmlNode xn = xd.SelectSingleNode(nodePath);
            if (xn == null) //检测节点是否存在
            {
                return "";
            }
            if (xn.Attributes[attrName] == null) //检测属性是否存在
            {
                return "";
            }

            return xn.Attributes[attrName].Value;
        }

        /// <summary>
        /// 获取某个节点
        /// </summary>
        /// <param name="nodePath"></param>
        /// <returns></returns>
        public XmlNode GetNode(string nodePath)
        {
            XmlNode xn = xd.SelectSingleNode(nodePath);
            return xn;
        }

        /// <summary>
        /// 获取某个节点子集合指定属性值的节点
        /// </summary>
        /// <param name="nodePath">父节点</param>
        /// <returns></returns>
        public XmlNode GetNode(string nodePath, string attrName, string attrValue)
        {
            XmlNodeList xl = GetChildNode(nodePath);
            if (xl != null)
            {
                foreach (XmlNode node in xl)
                {
                    if (node.Attributes[attrName] != null) //检测属性是否存在
                    {
                        if (node.Attributes[attrName].Value.Trim() == attrValue)
                        {
                            return node;
                        }
                    }
                }
            }
            return null;
        }

        /// <summary>
        /// 获取某个节点上的子节点
        /// </summary>
        /// <param name="nodePath"></param>
        /// <returns></returns>
        public XmlNodeList GetChildNode(string nodePath)
        {
            XmlNodeList xl = null;
            XmlNode xn = xd.SelectSingleNode(nodePath);
            if (xl != null)
            {
                xl = xd.ChildNodes;
            }
            return xl;
        }
     }
 }