×òåíèå XML èç ôàéëà ñ ïîìîùüþ Visual C#

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Òðåáîâàíèÿ

• Microsoft Visual Studio 2005 èëè Microsoft Visual Studio .NET

• Òåðìèíîëîãèÿ XML.
• Ñîçäàíèå è ÷òåíèå XML-ôàéëîâ.

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×òåíèå XML èç ôàéëà.

1. Çàïóñòèòå Visual Studio 2005 èëè Visual Studio .NET.
2. Ñîçäàéòå êîíñîëüíîå ïðèëîæåíèå Visual C#. Ïåðåéäèòå ñðàçó ê ðàçäåëó "Ïîëíûé ëèñòèíã êîäà" èëè ñîçäàéòå ïðèëîæåíèå, ïîñëåäîâàòåëüíî âûïîëíÿÿ ïðèâåäåííûå íèæå äåéñòâèÿ.
3. Óáåäèòåñü â òîì, ÷òî ïðîåêò ñîäåðæèò ññûëêó íà ñáîðêó System.Xml.dll.
4. Óêàæèòå äèðåêòèâó using â ïðîñòðàíñòâå èìåí System.Xml, ÷òîáû èçáàâèòüñÿ îò íåîáõîäèìîñòè óêàçûâàòü îáúÿâëåíèÿ XmlTextReader äàëåå â êîäå. Äèðåêòèâó using íåîáõîäèìî èñïîëüçîâàòü ïåðåä âñåìè îñòàëüíûìè îáúÿâëåíèÿìè.

   using System.Xml;
   					

5. Ñîçäàéòå ýêçåìïëÿð îáúåêòà XmlTextReader è çàïîëíèòå åãî XML-ôàéëîì. Êëàññ XmlTextReader îáû÷íî èñïîëüçóåòñÿ äëÿ äîñòóïà ê XML êàê ê íåôîðìàòèðîâàííûì äàííûì áåç èñïîëüçîâàíèÿ íàäñòðîéêè DOM; òàêèì îáðàçîì, êëàññ XmlTextReader îáåñïå÷èâàåò áîëåå áûñòðûé ìåõàíèçì ÷òåíèÿ XML. Êëàññ XmlTextReader èìååò ðàçëè÷íûå êîíñòðóêòîðû äëÿ óêàçàíèÿ ìåñòîïîëîæåíèÿ XML-äàííûõ.  ïðèâåäåííîì íèæå êîäå ñîçäàåòñÿ ýêçåìïëÿð êëàññà XmlTextReader è çàãðóæàåòñÿ ôàéë Books.xml. Äîáàâüòå ïðèâåäåííûé íèæå êîä â ïðîöåäóðó Main êëàññà Class1.

   XmlTextReader reader = new XmlTextReader ("books.xml");
   					

6. ×òåíèå XML. (Îòìåòèì, ÷òî â äàííîì äåéñòâèè ïîêàçàí âíåøíèé öèêë "while", à â ñëåäóþùèõ äâóõ äåéñòâèÿõ ïîêàçàíî èñïîëüçîâàíèå ýòîãî öèêëà äëÿ ÷òåíèÿ XML.) Ïîñëå ñîçäàíèÿ îáúåêòà XmlTextReader âîñïîëüçóéòåñü äëÿ ÷òåíèÿ äàííûõ XML ìåòîäîì Read. Ìåòîä Read ïîñëåäîâàòåëüíî ïåðåìåùàåòñÿ ïî XML-ôàéëó äî äîñòèæåíèÿ êîíöà ôàéëà, ïîñëå ÷åãî âîçâðàùàåò çíà÷åíèå "False".

   while (reader.Read())  
   {
       // Îáðàáîòêà äàííûõ.
   	Console.WriteLine(reader.Name);
   }
   Console.ReadLine();
   					

7. Èçó÷åíèå óçëîâ. Äëÿ îáðàáîòêè äàííûõ XML â êàæäîé çàïèñè ñîäåðæèòñÿ óçåë, òèï êîòîðîãî ìîæíî îïðåäåëèòü ïî ñâîéñòâó NodeType. Ñâîéñòâà Name è Value âîçâðàùàþò èìÿ óçëà (èìåíà ýëåìåíòà è àòðèáóòà) è çíà÷åíèå óçëà (òåêñò óçëà) òåêóùåãî óçëà (èëè çàïèñè). Ïåðå÷èñëåíèå NodeType îïðåäåëÿåò òèï óçëà.  ïðèâåäåííîì íèæå ïðèìåðå êîäà âûâîäèòñÿ èìÿ ýëåìåíòîâ è òèï äîêóìåíòà. Èìåéòå â âèäó, ÷òî â äàííîì ïðèìåðå ïðîïóùåíû àòðèáóòû ýëåìåíòîâ.

   while (reader.Read())  
   {
       switch (reader.NodeType)  
       {
           case XmlNodeType.Element: // Óçåë ÿâëÿåòñÿ ýëåìåíòîì.
               Console.Write("<" + reader.Name);
      Console.WriteLine(">");
               break;
     case XmlNodeType.Text: // Âûâåñòè òåêñò â êàæäîì ýëåìåíòå.
               Console.WriteLine (reader.Value);
               break;
     case XmlNodeType. EndElement: // Âûâåñòè êîíåö ýëåìåíòà.
               Console.Write("</" + reader.Name);
      Console.WriteLine(">");
               break;
       }
   }
   					

8. Ïðîâåðêà àòðèáóòîâ. Òèïû óçëîâ ýëåìåíòîâ ìîãóò âêëþ÷àòü ñïèñêè ñâÿçàííûõ ñ íèìè óçëîâ àòðèáóòîâ. Ìåòîä MovetoNextAttribute ïîñëåäîâàòåëüíî ïåðåìåùàåòñÿ ïî âñåì àòðèáóòàì ýëåìåíòà. Ñâîéñòâî HasAttributes èñïîëüçóåòñÿ äëÿ ïðîâåðêè íàëè÷èÿ ó óçëà àòðèáóòîâ. Ñâîéñòâî AttributeCount âîçâðàùàåò êîëè÷åñòâî àòðèáóòîâ äëÿ òåêóùåãî óçëà.

   while (reader.Read()) 
   {
          switch (reader.NodeType) 
          {
              case XmlNodeType.Element: // Óçåë ÿâëÿåòñÿ ýëåìåíòîì.
                  Console.Write("<" + reader.Name);
   
                  while (reader.MoveToNextAttribute()) // ×òåíèå àòðèáóòîâ.
                      Console.Write(" " + reader.Name + "='" + reader.Value + "'");
         Console.WriteLine(">");
                  break;
        case XmlNodeType.Text: // Âûâåñòè òåêñò â êàæäîì ýëåìåíòå.
                  Console.WriteLine (reader.Value);
                  break;
        case XmlNodeType. EndElement: // Âûâåñòè êîíåö ýëåìåíòà.
                  Console.Write("</" + reader.Name);
         Console.WriteLine(">");
                  break;
          }
      }
   					

9. Ñîõðàíèòå è çàêðîéòå ïðîåêò.

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Ïîëíûé ëèñòèíã êîäà

using System;
using System.Xml;

namespace ReadXMLfromFile
{
    /// <summary>
    /// Îáùåå îïèñàíèå êëàññà Class1.
    /// </summary>
    class Class1
    {
        static void Main(string[] args)
        {
            XmlTextReader reader = new XmlTextReader ("books.xml");
            while (reader.Read())  
            {
                switch (reader.NodeType)  
                {
                    case XmlNodeType.Element: // Óçåë ÿâëÿåòñÿ ýëåìåíòîì.
                        Console.Write("<" + reader.Name);
                        Console.WriteLine(">");
                        break;
                    case XmlNodeType.Text: // Âûâåñòè òåêñò â êàæäîì ýëåìåíòå.
                        Console.WriteLine (reader.Value);
                        break;
                    case XmlNodeType.EndElement: // Âûâåñòè êîíåö ýëåìåíòà.
                        Console.Write("</" + reader.Name);
                        Console.WriteLine(">");
                        break;
                }
            }
            Console.ReadLine();
        }
    }
}
				

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Ïðèìåð âûõîäíûõ äàííûõ

<bookstore>
<book>
<title>
Àâòîáèîãðàôèÿ Áåíäæàìèíà Ôðàíêëèíà
</title>
<author>
<first-name>
Áåíäæàìèí
</first-name>
<last-name>
Ôðàíêëèí
</last-name>
</author>
<price>
8.99
</price>
</book>
<book>
<title>
Ìîøåííèê
</title>
<author>
<first-name>
Ãåðìàí
</first-name>
<last-name>
Ìåëâèëë
</last-name>
</author>
<price>
11.99
</price>
</book>
<book>
<title>
Ãîðãèé
</title>
<author>
<name>
Ïëàòîí
</name>
</author>
<price>
9.99
</price>
</book>
</bookstore>
				

Ïåðåéòè ê íà÷àëó ñòðàíèöû

Óñòðàíåíèå íåïîëàäîê

(reader.Read())

<?xml version='1.0' ?>

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ÑÑÛËÊÈ

Ñâåðíóòü ýòî èçîáðàæåíèåÐàçâåðíóòü ýòî èçîáðàæåíèå

Çàãðóçèòü ïàêåò Books.exe. (http://download.microsoft.com/download/xml/utility/1.0.0.1/wxp/en-us/books.exe)

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