Proprietà XmlTextReader.Value (System.Xml)

Cambia visualizzazione:
Classica
Lightweight
ScriptFree
Riferimento a .NET Framework
Proprietà XmlTextReader.Value

Ottiene il valore di testo del nodo corrente.

Spazio dei nomi: System.Xml
Assembly: System.Xml (in system.xml.dll)

Sintassi
Visual Basic - (Dichiarazione)
Public Overrides ReadOnly Property Value As String
Visual Basic (Utilizzo)
Dim instance As XmlTextReader
Dim value As String

value = instance.Value
C#
public override string Value { get; }
C++
public:
virtual property String^ Value {
	String^ get () override;
}
J#
/** @property */
public String get_Value ()
JScript
public override function get Value () : String

Valore proprietà

Il valore restituito dipende dalla proprietà NodeType del nodo. Nella tabella seguente sono elencati i tipi di nodo che possono restituire un valore. Tutti gli altri tipi di nodo restituiscono String.Empty.

Tipo di nodo

Valore

Attribute

Valore dell'attributo.

CDATA

Contenuto della sezione CDATA.

Comment

Contenuto del commento.

DocumentType

Sottoinsieme interno.

ProcessingInstruction

Intero contenuto, ad eccezione della destinazione.

SignificantWhitespace

Spazio vuoto compreso in un ambito xml:space= 'preserve'.

Text

Contenuto del nodo testo.

Whitespace

Spazio vuoto tra parti di codice.

XmlDeclaration

Contenuto della dichiarazione.

Note
NotaNota

Nella versione Microsoft .NET Framework versione 2.0 è consigliabile creare istanze di XmlReader utilizzando il metodo System.Xml.XmlReader.Create. In questo modo è possibile sfruttare completamente le nuove funzionalità introdotte in questa versione. Per ulteriori informazioni, vedere Creazione di lettori XML.

Esempio

Nell'esempio seguente viene letto un file XML e vengono visualizzati tutti i nodi.

Visual Basic
Option Strict
Option Explicit

Imports System
Imports System.IO
Imports System.Xml

'Reads an XML document
Public Class Sample
    Private Const filename As String = "items.xml"
    
    Public Shared Sub Main()
        Dim reader As XmlTextReader = Nothing
        
        Try
            ' Load the reader with the data file and ignore all white space nodes.         
            reader = New XmlTextReader(filename)
            reader.WhitespaceHandling = WhitespaceHandling.None
            
            ' Parse the file and display each of the nodes.
            While reader.Read()
                Select Case reader.NodeType
                    Case XmlNodeType.Element
                        Console.Write("<{0}>", reader.Name)
                    Case XmlNodeType.Text
                        Console.Write(reader.Value)
                    Case XmlNodeType.CDATA
                        Console.Write("<![CDATA[{0}]]>", reader.Value)
                    Case XmlNodeType.ProcessingInstruction
                        Console.Write("<?{0} {1}?>", reader.Name, reader.Value)
                    Case XmlNodeType.Comment
                        Console.Write("<!--{0}-->", reader.Value)
                    Case XmlNodeType.XmlDeclaration
                        Console.Write("<?xml version='1.0'?>")
                    Case XmlNodeType.Document
                    Case XmlNodeType.DocumentType
                        Console.Write("<!DOCTYPE {0} [{1}]", reader.Name, reader.Value)
                    Case XmlNodeType.EntityReference
                        Console.Write(reader.Name)
                    Case XmlNodeType.EndElement
                        Console.Write("</{0}>", reader.Name)
                End Select
            End While
        
        Finally
            If Not (reader Is Nothing) Then
                reader.Close()
            End If
        End Try
    End Sub 'Main 
End Class 'Sample
C#
using System;
using System.IO;
using System.Xml;

public class Sample {

  private const String filename = "items.xml";

  public static void Main() {
  
     XmlTextReader reader = null;

     try {
       
        // Load the reader with the data file and ignore all white space nodes.         
        reader = new XmlTextReader(filename);
        reader.WhitespaceHandling = WhitespaceHandling.None;

        // Parse the file and display each of the nodes.
        while (reader.Read()) {
           switch (reader.NodeType) {
             case XmlNodeType.Element:
               Console.Write("<{0}>", reader.Name);
               break;
             case XmlNodeType.Text:
               Console.Write(reader.Value);
               break;
             case XmlNodeType.CDATA:
               Console.Write("<![CDATA[{0}]]>", reader.Value);
               break;
             case XmlNodeType.ProcessingInstruction:
               Console.Write("<?{0} {1}?>", reader.Name, reader.Value);
               break;
             case XmlNodeType.Comment:
               Console.Write("<!--{0}-->", reader.Value);
               break;
             case XmlNodeType.XmlDeclaration:
               Console.Write("<?xml version='1.0'?>");
               break;
             case XmlNodeType.Document:
               break;
             case XmlNodeType.DocumentType:
               Console.Write("<!DOCTYPE {0} [{1}]", reader.Name, reader.Value);
               break;
             case XmlNodeType.EntityReference:
               Console.Write(reader.Name);
               break;
             case XmlNodeType.EndElement:
               Console.Write("</{0}>", reader.Name);
               break;
           }       
        }           
     }

     finally {
        if (reader!=null)
          reader.Close();
     }
  }
} // End class
C++
#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   String^ filename = "items.xml";
   try
   {
      
      // Load the reader with the data file and ignore all white space nodes.         
      reader = gcnew XmlTextReader( filename );
      reader->WhitespaceHandling = WhitespaceHandling::None;
      
      // Parse the file and display each of the nodes.
      while ( reader->Read() )
      {
         switch ( reader->NodeType )
         {
            case XmlNodeType::Element:
               Console::Write( "<{0}>", reader->Name );
               break;

            case XmlNodeType::Text:
               Console::Write( reader->Value );
               break;

            case XmlNodeType::CDATA:
               Console::Write( "<![CDATA[{0}]]>", reader->Value );
               break;

            case XmlNodeType::ProcessingInstruction:
               Console::Write( "<?{0} {1}?>", reader->Name, reader->Value );
               break;

            case XmlNodeType::Comment:
               Console::Write( "<!--{0}-->", reader->Value );
               break;

            case XmlNodeType::XmlDeclaration:
               Console::Write( "<?xml version='1.0'?>" );
               break;

            case XmlNodeType::Document:
               break;

            case XmlNodeType::DocumentType:
               Console::Write( "<!DOCTYPE {0} [{1}]", reader->Name, reader->Value );
               break;

            case XmlNodeType::EntityReference:
               Console::Write( reader->Name );
               break;

            case XmlNodeType::EndElement:
               Console::Write( "</{0}>", reader->Name );
               break;
         }
      }
   }
   finally
   {
      if ( reader != nullptr )
            reader->Close();
   }

}
J#
import System.*;
import System.IO.*;
import System.Xml.*;

public class Sample
{
    private static String fileName = "items.xml";

    public static void main(String[] args)
    {
        XmlTextReader reader = null;
        try {

            // Load the reader with the data file and ignore 
            //all white space nodes.         
            reader = new XmlTextReader(fileName);
            reader.set_WhitespaceHandling(WhitespaceHandling.None);

            // Parse the file and display each of the nodes.
            while(reader.Read()) {
                switch(reader.get_NodeType() ) {
                    case XmlNodeType.Element : 
                        Console.Write("<{0}>", reader.get_Name());
                        break;
                    case XmlNodeType.Text : 
                        Console.Write(reader.get_Value());
                        break;
                    case XmlNodeType.CDATA : 
                        Console.Write("<![CDATA[{0}]]>", reader.get_Value());
                        break;
                    case XmlNodeType.ProcessingInstruction : 
                        Console.Write("<?{0} {1}?>", reader.get_Name(),
                        reader.get_Value());
                        break;
                    case XmlNodeType.Comment : 
                        Console.Write("<!--{0}-->", reader.get_Value());
                        break;
                    case XmlNodeType.XmlDeclaration : 
                        Console.Write("<?xml version='1.0'?>");
                        break;
                    case XmlNodeType.Document : 
                        break;
                    case XmlNodeType.DocumentType : 
                        Console.Write("<!DOCTYPE {0} [{1}]", reader.get_Name(),
                        reader.get_Value());
                        break;
                    case XmlNodeType.EntityReference : 
                        Console.Write(reader.get_Name());
                        break;
                    case XmlNodeType.EndElement : 
                        Console.Write("</{0}>", reader.get_Name());
                        break;
                }
            }
        }
        finally {
            if (reader != null) {
                reader.Close();
            }
        }
    } //main
} // End class Sample

Nell'esempio viene utilizzato il file items.xml.


<?xml version="1.0"?>
<!-- This is a sample XML document -->
<!DOCTYPE Items [<!ENTITY number "123">]>
<Items>
  <Item>Test with an entity: &number;</Item>
  <Item>test with a child element <more/> stuff</Item>
  <Item>test with a CDATA section <![CDATA[<456>]]> def</Item>
  <Item>Test with an char entity: &#65;</Item>
  <!-- Fourteen chars in this element.-->
  <Item>1234567890ABCD</Item>
</Items>
Piattaforme

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile per Pocket PC, Windows Mobile per Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework non supporta tutte le versioni di ciascuna piattaforma. Per un elenco delle versioni supportate, vedere Requisiti di sistema.

Informazioni sulla versione

.NET Framework

Supportato in: 2.0 1.1 1.0

.NET Compact Framework

Supportato in: 2.0 1.0
Vedere anche