.Net那点事儿系列:C#操作Xml:通过XmlDocument读写Xml文档(转http://www.cnblogs.com/yukaizhao/archive/2011/07/19/csharp_xmldocument_access_xml.html)

Coordinator
Dec 12, 2011 at 7:04 AM

.Net那点事儿系列:C#操作Xml
什么是Xml?

Xml是扩展标记语言的简写,是一种开发的文本格式。关于它的更多情况可以通过w3组织了解http://www.w3.org/TR/1998/REC-xml-19980210。如果你不知道它,那你就out太多了。
.Net是如何处理Xml的?

通过XmlDocument读写Xml文档
有如下一段Xml:
<?xml version="1.0" encoding="utf-8" ?>
<students>
  <!--我是一段注释文字-->
  <student name="张平">
    <courses>
      <course name="语文?">
        <teacherComment>
          <![CDATA[
        这里是语文老师的批注
        ]]>
        </teacherComment>      
    </course>
  
      <course name="数学">
        <teacherComment>
          <![CDATA[
        这里是数学老师的批注
        ]]>
        </teacherComment>
      </course>
    </courses>
  </student>
</students>
1.如何使用XmlDocument读取Xml

我要用一段代码遍历所有Student,并打印Student的所有属性和子节点的值
using System;
using System.Collections.Generic;
using System.Text;
using System.Xml;
  
namespace XmlExample
{
    class Program
    {
        static void Main(string[] args)
        {
            string xmlFilePath = @"X:\about.net\example\XmlExample\1.xml";
            XmlDocument doc = new XmlDocument();
            doc.Load(xmlFilePath);
  
            //使用xpath表达式选择文档中所有的student子节点
            XmlNodeList studentNodeList = doc.SelectNodes("/students/student");
            if (studentNodeList != null)
            {
                foreach (XmlNode studentNode in studentNodeList)
                {
                    //通过Attributes获得属性名字为name的属性
                    string name = studentNode.Attributes["name"].Value;
                    Console.WriteLine("Student:" + name);
  
                    //通过SelectSingleNode方法获得当前节点下的courses子节点
                    XmlNode coursesNode = studentNode.SelectSingleNode("courses");
  
                    //通过ChildNodes属性获得courseNode的所有一级子节点
                    XmlNodeList courseNodeList = coursesNode.ChildNodes;
                    if (courseNodeList != null)
                    {
                        foreach (XmlNode courseNode in courseNodeList)
                        {
                            Console.Write("\t");
                            Console.Write(courseNode.Attributes["name"].Value);
                            Console.Write("老师评语");
                            //通过FirstNode属性可以获得课程节点的第一个子节点,LastNode可以获得最后一个子节点
                            XmlNode teacherCommentNode = courseNode.FirstChild;
                            //读取CData节点
                            XmlCDataSection cdata = (XmlCDataSection)teacherCommentNode.FirstChild;
                            Console.WriteLine(cdata.InnerText.Trim());
                        }
                    }
                }
            }
  
            Console.Write("\r\nPress any key to continue....");
            Console.Read();
        }
    }
}
XmlDocument本身是从XmlNode继承的,读Xml节点可以通过FirstChild,LastChild,或者NextSibling,PreviousSibling读取单个节点,或者通过ChildNodes读取所有子节点。还可以使用XPath表达式使用SelectNodes(string xpath)或者SelectSingleNode(string xpath)读取单个或者多个符合条件的节点。
2.如何通过XmlDocument编辑Xml
同样是读取Xml中的xml例子,我们这次要用csharp代码生成xml,如下代码:
using System;
using System.Collections.Generic;
using System.Text;
using System.Xml;
  
namespace WriteXml
{
    class Program
    {
        static void Main(string[] args)
        {
            XmlDocument xmlDoc = new XmlDocument();
            //创建Xml声明部分,即<?xml version="1.0" encoding="utf-8" ?>
            xmlDoc.CreateXmlDeclaration("1.0", "utf-8", "yes");
  
            //创建根节点
            XmlNode rootNode = xmlDoc.CreateElement("students");
  
            //创建student子节点
            XmlNode studentNode = xmlDoc.CreateElement("student");
            //创建一个属性
            XmlAttribute nameAttribute = xmlDoc.CreateAttribute("name");
            nameAttribute .Value = "张同学";
            //xml节点附件属性
            studentNode.Attributes.Append(nameAttribute);
  
             
            //创建courses子节点
            XmlNode coursesNode = xmlDoc.CreateElement("courses");
            XmlNode courseNode1 = xmlDoc.CreateElement("course");
            XmlAttribute courseNameAttr = xmlDoc.CreateAttribute("name");
            courseNameAttr.Value = "语文";
            courseNode1.Attributes.Append(courseNameAttr);
            XmlNode teacherCommentNode = xmlDoc.CreateElement("teacherComment");
            //创建Cdata块
            XmlCDataSection cdata = xmlDoc.CreateCDataSection("<font color=\"red\">这是语文老师的批注</font>");
            teacherCommentNode.AppendChild(cdata);
            courseNode1.AppendChild(teacherCommentNode);
            coursesNode.AppendChild(courseNode1);
            //附加子节点
            studentNode.AppendChild(coursesNode);
  
            rootNode.AppendChild(studentNode);
            //附加根节点
            xmlDoc.AppendChild(rootNode);
  
            //保存Xml文档
            xmlDoc.Save(@"d:\test.xml");
  
            Console.WriteLine("已保存Xml文档");
  
  
        }
    }
}

使用XmlDocument生成xml的要点在于使用xmlDocument的实例的CreateElement创建XmlNode或者通过CreateAttribute方法创建属性,并通过AppendChild方法附加xml节点,通过AppendAttribute附加Attribute到节点的属性集合。