如何在 c# 2.0/3.0 上选择指定值的 xmlelements xmlnodes xmlattributes

Posted 2023-02-16

【中文标题】如何在 c# 2.0/3.0 上选择指定值的 xmlelements xmlnodes xmlattributes

【英文标题】：how to select xmlelements xmlnodes xmlattributes of specified values on c# 2.0/3.0

【发布时间】：2013-11-19 18:06:46

【问题描述】：

这是我的 xml 文档，看起来像这样

<?xml version="1.0" encoding="UTF-8"?>
<bookstore> 
<book category="cooking">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year updated="no" version="3.5">2005</year>
<price>30.00</price>
</book>
<book category="children">
<title lang="fr">Harry Potter</title>
<author>J K. Rowling</author>
<year updated="yes" version="2.0">2005</year>
<price>29.99</price>
</book>
</bookstore>

1-如何选择所有books并打印他们的element's text（标题，作者，...）？

2-如何仅从year获取每本书的langfromtitle和version的值？

3-如何选择所有bookswherecategory="cooking"并打印所有元素？

4-如何选择title的lang为en的所有书籍并打印其所有元素值？

【参考方案1】：

在这种情况下，这些版本的框架不支持XDocument class 所以我们使用XmlDocument

 XmlDocument myXmlDoc = new XmlDocument();
 myXmlDoc.Load(@"c:\books.xml"); //wich is above you can use uri location
 XmlNodeList list = myXmlDoc.SelectNodes("/bookstore/book");
  //Selecting all book nodes then extract title author year  
  foreach (XmlNode mynode in list)
  
  Console.WriteLine(mynode["title"].InnerText);
  Console.WriteLine(mynode["author"].InnerText);
  Console.WriteLine(mynode["year"].InnerText);
  Console.WriteLine(mynode["price"].InnerText);
  Console.WriteLine("------------");
  
  //OUTPUT :
  Everyday Italian
  Giada De Laurentiis
  2005
  30.00
  -----------------------
  Harry Potter
  J K. Rowling
  2005
  29.99
  -----------------------
  //get the value of `lang` from `title` and `version` from `year` :
   foreach (XmlNode mynode in list)
   
       Console.WriteLine(mynode["title"].Attributes["lang"].Value );
  Console.WriteLine(mynode["year"].Attributes["version"].Value );
 Console.WriteLine("------------");
        
//OUTPUT : 

  en
  3.5
  ----------------
  fr
  2.0

  //get books that have category="children" and print all both firstane lastname .....
  XmlNodeList list = myXmlDoc.SelectNodes("/bookstore/book[@category='children']");
    foreach (XmlNode mynode in list)
      
   Console.WriteLine(mynode["title"].InnerText );
   Console.WriteLine(mynode["author"].InnerText);
    Console.WriteLine(mynode["price"].InnerText);
        

//OUTPUT:
Harry Potter
J K. Rowling
29.99

//select books where the `lang` of `title` is `en`

 XmlNodeList list = myXmlDoc.SelectNodes("/bookstore/book/title[@lang='en']");
              foreach (XmlNode mynode in list)
        
            Console.WriteLine(mynode.ParentNode["title"].InnerText );
            Console.WriteLine(mynode.ParentNode["author"].InnerText);
            Console.WriteLine(mynode.ParentNode["price"].InnerText);
        

    //OUTPUT:

    Everyday Italian
        Giada De Laurentiis
        30.00