步步为营-21-xml的增删改查

1 增加(存在则添加,不存在则新建)

            //对xml的操作--
            XmlDocument doc = new XmlDocument();
            if (File.Exists("Person.xml"))
            {
                //如果存在,加载文档
                doc.Load("Person.xml");
                //获取根节点
                XmlElement person = doc.DocumentElement;

                XmlElement student = doc.CreateElement("Student");
                student.SetAttribute("ID", "110");


                XmlElement name = doc.CreateElement("Name");
                name.InnerXml = "张三";
                student.AppendChild(name);

                XmlElement age = doc.CreateElement("Age");
                age.InnerXml = "110";
                student.AppendChild(age);

                XmlElement gender = doc.CreateElement("Gender");
                gender.InnerXml = "男";
                student.AppendChild(gender);


                person.AppendChild(student);

            }
            else
            {
                //不存在创建
                XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", "utf-8", null);
                doc.AppendChild(dec);
                XmlElement person = doc.CreateElement("Person");
                doc.AppendChild(person);

                XmlElement student = doc.CreateElement("Student");
                student.SetAttribute("ID", "0");


                XmlElement name = doc.CreateElement("Name");
                name.InnerXml = "逍遥小天狼";
                student.AppendChild(name);

                XmlElement age = doc.CreateElement("Age");
                age.InnerXml = "18";
                student.AppendChild(age);

                XmlElement gender = doc.CreateElement("Gender");
                gender.InnerXml = "男";
                student.AppendChild(gender);


                person.AppendChild(student);
            }
            doc.Save("Person.xml");

2 查询

         //02-1 先加载
            doc.Load("Person.xml");
            //02-2 获取根节点
            XmlElement person = doc.DocumentElement;
            //02-3 将根节点下所有的子节点拿出来,放入到LNodeList中
            XmlNodeList xnl = person.ChildNodes;
            //02-4 显示
            foreach (XmlNode item in xnl)
            {
                Console.WriteLine(item.InnerText);
            }
    

2.2 获取属性

//02-5 获取属性-修改节点
            //获取字节s的方法
            XmlNodeList Students = person.SelectNodes("Student");
            foreach (XmlNode item in Students)
            {
                Console.WriteLine(item.Attributes["ID"].Value);
                if (item.Attributes["ID"].Value=="110")
                {
                    //获取子节点方法   修改节点
                    item["Name"].InnerXml = "修改了名字";
                }
            }
            doc.Save("Person.xml");

3 另一种读取xml文件方法 x-path

     #region 03-通过x-path获取数据
            doc.Load("Person.xml");
            //03-01 获取根节点
            XmlElement person = doc.DocumentElement;
            XmlNode xn = person.SelectSingleNode("/Person/Student[@ID='110']/Name");
            Console.WriteLine(xn.InnerText);
            #endregion

4 删除

 //04-01 加载文件,找到根节点
            doc.Load("Person.xml");
            XmlElement person = doc.DocumentElement;
            person.RemoveAll();
            Console.WriteLine("删除成功");

5 删除部分节点

//05-01 加载文件,找到根节点
            doc.Load("Person.xml");
            XmlElement person = doc.DocumentElement;
            XmlNode xn = person.SelectSingleNode("/Person/Student[@ID='110']/Age");
            //注意不能直接删除,需要父节点删除
            xn.ParentNode.RemoveAll();
            Console.WriteLine("删除成功");
            doc.Save("Person.xml");

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