读取,添加，修改xml文件

    /// <summary>
    /// 读取,添加，修改xml文件
    /// </summary>
    /// <param name="Xmlpath">Xml路径</param>
    /// <param name="Node">新的子节点名称</param>
    /// <param name="Value">新节点对应的值</param>
    /// <param name="flag">1：读取，否则为 修改或者添加</param>
    /// <returns>1：修改添加成功，为空字符串表示修改添加成功，否则是读取成功</returns>
    public static string getXML(string Xmlpath,string Node,string Value,int flag)
    {
        try
        {
            string filepath = HttpContext.Current.Server.MapPath(Xmlpath);
            XmlDocument xmlDoc = new XmlDocument();
            if (!File.Exists(filepath))
            {
                XmlDeclaration xn = xmlDoc.CreateXmlDeclaration("1.0","utf-8",null);
                XmlElement root = xmlDoc.CreateElement("rss");
                XmlElement root1 = xmlDoc.CreateElement("item");

                root.AppendChild(root1);
                xmlDoc.AppendChild(xn);
                xmlDoc.AppendChild(root);
                xmlDoc.Save(filepath);//本地路径名字
            }
            xmlDoc.Load(filepath);//你的xml文件
            string ReStr = string.Empty;
            XmlElement xmlObj = xmlDoc.DocumentElement;

            XmlNodeList xmlList = xmlDoc.SelectSingleNode(xmlObj.Name.ToString()).ChildNodes;

            foreach (XmlNode xmlNo in xmlList)
            {
                if (xmlNo.NodeType != XmlNodeType.Comment)//判断是不是注释类型
                {
                    XmlElement xe = (XmlElement)xmlNo;
                    {
                        if (xe.Name == xmlObj.FirstChild.Name)
                        {
                            XmlNodeList xmlNList = xmlObj.FirstChild.ChildNodes;

                            foreach (XmlNode xmld in xmlNList)
                            {
                                XmlElement xe1 = (XmlElement)xmld;
                                {
                                    if (xe1.Name == Node)
                                    {
                                        if (flag == 1)//读取值
                                        {
                                            if (xmld.InnerText != null && xmld.InnerText != "")
                                            {
                                                ReStr = xmld.InnerText;
                                            }
                                        }
                                        else//修改值
                                        {
                                            xmld.InnerText = Value;//给节点赋值
                                            xmlDoc.Save(filepath);
                                            ReStr = Value.Trim();
                                        }
                                    }
                                }
                            }
                            if (ReStr == string.Empty)// 添加节点
                            {
                                XmlNode newNode;
                                newNode = xmlDoc.CreateNode("element",Node,Value);//创建节点
                                newNode.InnerText = Value;//给节点赋值
                                xe.AppendChild(newNode);//把节点添加到doc
                                xmlDoc.Save(filepath);
                                ReStr = Value.Trim();
                            }
                        }
                    }
                }
            }
            return ReStr;
        }
        catch
        {
            return string.Empty;
        }
    }