XmlWriter.LookupPrefix-Methode

Gibt beim Überschreiben in einer abgeleiteten Klasse das nächstliegende Präfix zurück, das im aktuellen Namespacebereich für den Namespace-URI definiert ist.

Namespace: System.Xml
Assembly: System.Xml (in system.xml.dll)

Syntax

'Declaration
Public MustOverride Function LookupPrefix ( _
    ns As String _
) As String
'Usage
Dim instance As XmlWriter
Dim ns As String
Dim returnValue As String

returnValue = instance.LookupPrefix(ns)

public abstract string LookupPrefix (
    string ns
)

public:
virtual String^ LookupPrefix (
    String^ ns
) abstract

public abstract String LookupPrefix (
    String ns
)

public abstract function LookupPrefix (
    ns : String
) : String

Parameter

• ns
  Der Namespace-URI, dessen Präfix gesucht werden soll.

Rückgabewert

Das passende Präfix oder NULL (Nothing in Visual Basic), wenn im aktuellen Gültigkeitsbereich kein übereinstimmender Namespace-URI gefunden wird.

Ausnahmen

Ausnahmetyp	Bedingung
ArgumentException	ns ist entweder NULL (Nothing in Visual Basic) oder String.Empty.

Beispiel

Im folgenden Beispiel wird ein Buch geschrieben.

Option Strict
Option Explicit

Imports System
Imports System.IO
Imports System.Xml

Public Class Sample
    Private Shared m_Document As String = "sampledata.xml"
    
    Public Shared Sub Main()
        Dim writer As XmlWriter = Nothing
        
      Try

        Dim settings As XmlWriterSettings = new XmlWriterSettings()
        settings.Indent = true
        writer = XmlWriter.Create (m_Document)
            
        writer.WriteComment("sample XML fragment")
            
        ' Write an element (this one is the root).
        writer.WriteStartElement("book")
            
        ' Write the namespace declaration.
        writer.WriteAttributeString("xmlns", "bk", Nothing, "urn:samples")
            
        ' Write the genre attribute.
        writer.WriteAttributeString("genre", "novel")
            
        ' Write the title.
        writer.WriteStartElement("title")
        writer.WriteString("The Handmaid's Tale")
        writer.WriteEndElement()
            
        ' Write the price.
        writer.WriteElementString("price", "19.95")
            
        ' Lookup the prefix and write the ISBN element.
        Dim prefix As String = writer.LookupPrefix("urn:samples")
        writer.WriteStartElement(prefix, "ISBN", "urn:samples")
        writer.WriteString("1-861003-78")
        writer.WriteEndElement()
            
        ' Write the style element (shows a different way to handle prefixes).
        writer.WriteElementString("style", "urn:samples", "hardcover")
            
        ' Write the close tag for the root element.
        writer.WriteEndElement()
            
        ' Write the XML to file and close the writer.
        writer.Flush()
        writer.Close()
        
        Finally
            If Not (writer Is Nothing) Then
                writer.Close()
            End If
        End Try

    End Sub 'Main 
End Class 'Sample

using System;
using System.IO;
using System.Xml;
 
 public class Sample
 {
   private const string m_Document = "sampledata.xml";
 
   public static void Main() {
   
      XmlWriter writer = null;

      try {
     
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Indent = true;
        writer = XmlWriter.Create (m_Document);
           
        writer.WriteComment("sample XML fragment");
     
        // Write an element (this one is the root).
        writer.WriteStartElement("book");
 
        // Write the namespace declaration.
        writer.WriteAttributeString("xmlns", "bk", null, "urn:samples");
    
        // Write the genre attribute.
        writer.WriteAttributeString("genre", "novel");
         
        // Write the title.
        writer.WriteStartElement("title");
        writer.WriteString("The Handmaid's Tale");
        writer.WriteEndElement();
               
        // Write the price.
        writer.WriteElementString("price", "19.95");
      
        // Lookup the prefix and write the ISBN element.
        string prefix = writer.LookupPrefix("urn:samples");
        writer.WriteStartElement(prefix, "ISBN", "urn:samples");
        writer.WriteString("1-861003-78");
        writer.WriteEndElement();

        // Write the style element (shows a different way to handle prefixes).
        writer.WriteElementString("style", "urn:samples", "hardcover");
 
        // Write the close tag for the root element.
        writer.WriteEndElement();
               
        // Write the XML to file and close the writer.
        writer.Flush();
        writer.Close();
      }

      finally {
        if (writer != null)
           writer.Close();
     } 
   }
 
 }

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
public ref class Sample
{
private:
   static String^ m_Document = L"sampledata.xml";

public:
   static void Main()
   {
      XmlWriter^ writer = nullptr;
      try
      {
         XmlWriterSettings^ settings = gcnew XmlWriterSettings;
         settings->Indent = true;
         writer = XmlWriter::Create( m_Document );
         writer->WriteComment( L"sample XML fragment" );
         
         // Write an element (this one is the root).
         writer->WriteStartElement( L"book" );
         
         // Write the namespace declaration.
         writer->WriteAttributeString( L"xmlns", L"bk", nullptr, L"urn:samples" );
         
         // Write the genre attribute.
         writer->WriteAttributeString( L"genre", L"novel" );
         
         // Write the title.
         writer->WriteStartElement( L"title" );
         writer->WriteString( L"The Handmaid's Tale" );
         writer->WriteEndElement();
         
         // Write the price.
         writer->WriteElementString( L"price", L"19.95" );
         
         // Lookup the prefix and write the ISBN element.
         String^ prefix = writer->LookupPrefix( L"urn:samples" );
         writer->WriteStartElement( prefix, L"ISBN", L"urn:samples" );
         writer->WriteString( L"1-861003-78" );
         writer->WriteEndElement();
         
         // Write the style element (shows a different way to handle prefixes).
         writer->WriteElementString( L"style", L"urn:samples", L"hardcover" );
         
         // Write the close tag for the root element.
         writer->WriteEndElement();
         
         // Write the XML to file and close the writer.
         writer->Flush();
         writer->Close();
      }
      finally
      {
         if ( writer != nullptr )
                  writer->Close();
      }

   }

};

void main()
{
   Sample::Main();
}

Plattformen

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

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 2.0, 1.0

Siehe auch

Referenz

XmlWriter-Klasse
XmlWriter-Member
System.Xml-Namespace

Weitere Ressourcen

Schreiben von XML mit dem "XmlWriter"