xml linq

这里讲解一下linq对xml的基本操作，包括：

• 新建xml、新建节点
• 查询节点
• 插入属性、插入节点
• 替换节点

在这里我封装了一些常用的方法：

public class XmlHelper
    {
        /// <summary>
        /// xml路径名
        /// </summary>
        public string XmlPath { get; set; }

        /// <summary>
        /// 初始化XmlPath
        /// </summary>
        /// <param name="xmlPath"></param>
        public XmlHelper(string xmlPath)
        {
            XmlPath = string.IsNullOrEmpty(xmlPath) ? "./my.xml" : xmlPath;
        }

        /// <summary>
        /// 初始化XML文件,如果原来有内容会被重置
        /// </summary>
        /// <param name="root">root名</param>
        public void InitXml(string root = null)
        {
            if (!File.Exists(XmlPath))
            {
                File.Create(XmlPath).Close();
            }
            if (root == null)
            {
                root = @"root";
            }
            XDocument xdoc = new XDocument(
                new XDeclaration("1.0", "utf-8", "yes"),
                new XElement(root, null)
                );
            xdoc.Save(XmlPath);
        }


        /// <summary>
        /// 创建Element
        /// </summary>
        /// <param name="elementName">ElementName</param>
        /// <param name="elementValue">ElementValue</param>
        /// <param name="xAttributes">属性数组（可选）</param>
        /// <returns></returns>
        public XElement CreateElement(string elementName, string elementValue, params XAttribute[] xAttributes)
        {
            XElement xElement = new XElement(elementName, elementValue);
            if (xAttributes != null)
            {
                foreach (XAttribute xAttribute in xAttributes)
                {
                    xElement.SetAttributeValue(xAttribute.Name, xAttribute.Value);
                }
            }
            return xElement;
        }


        /// <summary>
        /// 查询第一个指定itemName的节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <returns></returns>
        public XElement QueryFirstElementByName(string itemName)
        {
            XElement xele = XElement.Load(XmlPath);
            if (xele.Name == itemName)
            {
                return xele;
            }
            else
            {
                XElement xele1 = xele.Element("item");
                return xele1;
            }
        }

        /// <summary>
        /// 查询查询第一个指定itemName、itemValue的节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <returns></returns>
        public XElement QueryElementByNameAndValue(string itemName, string itemValue)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).FirstOrDefault();
            return item;
        }

        /// <summary>
        /// 查询节点，通过itemName 和属性
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="strAttributeName"></param>
        /// <param name="strAttributeValue"></param>
        /// <returns></returns>
        public XElement QueryElementByNameAndAttri(string itemName, string strAttributeName,
            string strAttributeValue)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Attribute(strAttributeName).Value == strAttributeValue
                select ele).FirstOrDefault();

            return item;
        }

        /// <summary>
        /// 在指定节点后添加节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="xElement"></param>
        public void AddToElementAfter(string itemName, string itemValue, XElement xElement)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).SingleOrDefault();
            if (item != null)
            {
                item.AddAfterSelf(xElement);
            }

            xele.Save(XmlPath);
        }

        /// <summary>
        /// 在指定节点前添加节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="xElement"></param>
        public void AddToElementBefore(string itemName, string itemValue, XElement xElement)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).SingleOrDefault();
            if (item != null)
            {
                item.AddBeforeSelf(xElement);
            }

            xele.Save(XmlPath);
        }

        /// <summary>
        /// 在指定节点名下添加节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="xElement"></param>
        public void AddElement(string itemName, XElement xElement)
        {
            XElement xele = XElement.Load(XmlPath);
            if (itemName == xele.Name)
            {
                xele.Add(xElement);
            }
            else
            {
                XElement item = xele.Element(itemName);
                if (item != null)
                {
                    item.Add(xElement);
                }
            }

            //var item = (from ele in xele.Elements(itemName)
            //            where ele.Value.Equals(null)
            //            select ele).SingleOrDefault();

            xele.Save(XmlPath);
        }
        /// <summary>
        /// 在指定节点下添加节点
        /// </summary>
        /// <param name="rootElement"></param>
        /// <param name="xElement"></param>
        public void AddElement(XElement rootElement, XElement xElement)
        {
            XElement xele = XElement.Load(XmlPath);
            if (xele.Name == rootElement.Name)
            {
                xele.Add(xElement);
            }
            else
            {
                var root = xele.Element(rootElement.Name.LocalName);
                if (root != null)
                {
                    root.Add(xElement);
                }
            }
            xele.Save(XmlPath);
        }

        /// <summary>
        /// 为指定节点添加属性
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="attributeName"></param>
        /// <param name="attributeValue"></param>
        public void AddAttributeToEle(string itemName, string itemValue, string attributeName,
            string attributeValue)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).SingleOrDefault();
            if (item != null)
            {
                item.SetAttributeValue(attributeName, attributeValue);
            }
            xele.Save(XmlPath);
        }

        /// <summary>
        /// 在指定节点后添加注释
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="xcomment"></param>
        public void AddCommentToAfter(string itemName, string itemValue, string xcomment)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).SingleOrDefault();
            if (item != null)
            {
                XComment xcom = new XComment(xcomment);
                item.AddAfterSelf(xcom);
                xele.Save(XmlPath);
            }
        }

        /// <summary>
        /// 在指定节点前添加注释
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="xcomment"></param>
        public void AddCommentToBefore(string itemName, string itemValue, string xcomment)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).SingleOrDefault();
            if (item != null)
            {
                XComment xcom = new XComment(xcomment);
                item.AddBeforeSelf(xcom);
                xele.Save(XmlPath);
            }
        }

        /// <summary>
        /// 替换指定节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="xElement"></param>
        public void ReplaceElement(string itemName, string itemValue, XElement xElement)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).FirstOrDefault();
            if (item != null)
            {
                item.ReplaceWith(xElement);
            }
            xele.Save(XmlPath);
        }

        /// <summary>
        /// 移除指定属性
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        /// <param name="strAttribute"></param>
        public void RemoveAttribute(string itemName, string itemValue, string strAttribute)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).FirstOrDefault().Attribute(strAttribute);
            if (item != null)
            {
                item.Remove();
            }
            xele.Save(XmlPath);
        }

        /// <summary>
        /// 移除指定节点
        /// </summary>
        /// <param name="itemName"></param>
        /// <param name="itemValue"></param>
        public void RemoveElement(string itemName, string itemValue)
        {
            XElement xele = XElement.Load(XmlPath);
            var item = (from ele in xele.Elements(itemName)
                where ele.Value.Equals(itemValue)
                select ele).FirstOrDefault();
            if (item != null)
            {
                item.Remove();
            }
            xele.Save(XmlPath);
        }
    }

经过验证，速度还是挺快的，但是如果要短时间操作大量数据的话，就应该自己封装一下自己需要的功能来加快速度，或者使用其他方法。