C#中处理xml文档

关键字： C# XML XPath

C#下处理xml是通过XML.NET API类来实现的. XML.NET构架是XML DOM接口的Wrapper,在高层提供了对xml编程的实现.
XML.NET的核心类是XmlDocument, XmlReader, and XmlWriter,被包括在System.xml命名空间中.

XmlReader和XmlWriter是用于读写XML数据的抽象基类.XmlTextReader,XmlValidatingReader,XmlNodeReader是XmlReader的具体实现;而XmlTextWriter和XmlNodeWriter则是XmlWriter的具体实现.XmlDocument类通过和XmlNode, XmlElement, and XmlAttribute类一起以树形的结构形式代表了一个具体的Xml文档.

System.Xml.Xsl接口和其具体类提供了对XSLT的实现;XPathDocument类和XPathNavigator类则提供了对Xml遍历等的相关操作.

现在以下面的movie.xml文档为例(被保存在C盘下C:\movie.xml),来说明如何对Xml文档进行操作.

<?xml version="1.0" encoding="utf-8"?>
 <movies>
  <movie>
    <name>Blade Runner</name>
    <category>Sci-Fi</category>
    <releaseRegion>USA</releaseRegion>
    <releaseTime>1982-6-25</releaseTime>
    <director>Ridley Scott</director>
    <price>27.95</price>
    <isrc>US-F18-06-0428-0/V.J9</isrc>
  </movie>
  <movie>
    <name>Brazil</name>
    <category>Fantasy</category>
    <releaseRegion>USA</releaseRegion>
    <releaseTime>1985-12-18</releaseTime>
    <director>Terry Gilliam</director>
    <price>29.98</price>
    <isrc>US-F18-07-8428-0/V.J9</isrc>
  </movie>
</movies>

读xml文档

public void readXmlData()
{
    XmlTextReader reader = new XmlTextReader("C:/books.Xml");
    while (reader.Read())
    {
        if (reader.HasValue)
        {
            Console.WriteLine("Name : "+ reader. Name);
            Console.WriteLine("Node Depth: " + reader.Depth.ToString( ));
            Console.WriteLine("Value : " + reader.Value);
        }
    }
}

写xml文档

public void writeXmlData()
{           
    XmlTextWriter writer = new XmlTextWriter("C:\\movie.xml" , null);
    try {
            writer.Formatting = Formatting.Indented;
            writer.Indentation = 4;
            //writer.XmlSpace = false;
            writer.WriteStartDocument();
            writer.WriteStartElement("movies");
            writer.WriteStartElement("movie");
            writer.WriteStartElement("name", "");
            writer.WriteString("Blade Runner");
            writer.WriteEndElement();
            writer.WriteStartElement("category", "");
            writer.WriteString("Sci-Fi");
            writer.WriteEndElement();
            writer.WriteStartElement("releaseRegion", "");
            writer.WriteString("USA");
            writer.WriteEndElement();
            writer.WriteStartElement("releaseTime", "");
            writer.WriteString("1982-6-25");
            writer.WriteEndElement();
            writer.WriterStartElement("director","");
            writer.WriteString("Ridley Scott");
            writer.WriterEndElement();
            writer.WriterStartElement("price","");
            writer.WriteString("27.95");
            writer.WriterEndElement();
            writer.WriteStartElement("isrc", "");
            writer.WriteString("US-F18-06-0428-0/V.J9");
            writer.WriteEndElement();

            write.WriteEndElement();
            write.WriteEndDocument();
            write.Flush();
        }catch (Exception e) {
            Console.WriteLine("Exception: {0}", e.ToString());
        }
}

在xml中追加节点内容(movie节点)

public void appendXmlNode()
    {           
        try
        {
            XmlDocument doc = new XmlDocument();
            doc.Load("C:\\movie.xml" );
            XmlNode root = doc.DocumentElement;
            XmlElement movieElement = doc.CreateElement("movie");
            XmlElement name = doc.CreateElement("name");
            name.InnerText = "Brazil";
            movieElement.AppendChild(name);
            XmlElement category = doc.CreateElement("category");
            category.InnerText = "Fantasy";
            movieElement.AppendChild(category);
            XmlElement releaseRegionElement = doc.CreateElement("releaseRegion");
            releaseRegionElement.InnerText = "USA";
            movieElement.AppendChild(releaseRegionElement);
            XmlElement releaseTimeElement = doc.CreateElement("releaseTime");
            releaseTimeElement.InnerText = "1985-12-18" ;
            movieElement.AppendChild(releaseTimeElement);
            XmlElement directorElement = doc.CreateElement("director");
            directorElement.InnerText = "Terry Gilliam";
            movieElement.AppendChild(directorElement);
            XmlElement priceElement = doc.CreateElement("price");
            priceElement.InnerText = "29.98";
            movieElement.AppendChild(priceElement);
            XmlElement isrcElement = doc.CreateElement("isrc");
            isrcElement.InnerText = "US-F18-06-0428-0/V.J9";
            movieElement.AppendChild(isrcElement);
            root.AppendChild(movieElement);
            doc.Save(Constants .movieFile );
        }
        catch (Exception e)
        {
            Console.WriteLine("Exception: {0}", e.ToString());
        }

}

遍历xml文档

System.Xml.XPath包中的XPathNavigator,XPathNodeIterator,XPathExpression等类实现了通过XPath语法遍历,获取具体节点相关信息的操作.

public void traverse()
    {            
        XmlDocument doc = new XmlDocument();
        doc.Load("C:\\movie.xml");
        XPathNavigator nav = doc.CreateNavigator();
        XPathNodeIterator iterator = nav.Select("/movies/movie[name[contains(text(),'" + "Blade" + "')]]");
        int count = iterator.Count;
        Console.WriteLine("count: "+ count);
        while(iterator .MoveNext() )
        {
            XPathNavigator movieNav = iterator.Current;
            movieNav.MoveToFirstChild();
            String name = movieNav.Value.ToString();
            Console.WriteLine("name: "+ name);
        }
    }