XmlTextWriter.LookupPrefix(String) Méthode

Définition

Espace de noms:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlTextWriter.cs

Retourne le préfixe le plus proche défini dans la portée espace de noms actuelle pour l'URI de l'espace de noms.

public:
 override System::String ^ LookupPrefix(System::String ^ ns);

public override string? LookupPrefix (string ns);

override this.LookupPrefix : string -> string

Public Overrides Function LookupPrefix (ns As String) As String

Paramètres

ns

String

URI de l'espace de noms dont vous recherchez le préfixe.

Retours

String

Préfixe correspondant. Ou null s'il n'existe aucun URI d'espace de noms dans la portée actuelle.

Exceptions

ArgumentException

ns a la valeur null ou String.Empty.

Exemples

L’exemple suivant écrit un livre.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   String^ filename = "sampledata.xml";
   XmlTextWriter^ writer = gcnew XmlTextWriter( filename, nullptr );
   
   //Use indenting for readability.
   writer->Formatting = Formatting::Indented;
   writer->WriteComment( "sample XML fragment" );
   
   //Write an element (this one is the root).
   writer->WriteStartElement( "bookstore" );
   
   //Write the namespace declaration.
   writer->WriteAttributeString( "xmlns", "bk", nullptr, "urn:samples" );
   writer->WriteStartElement( "book" );
   
   //Lookup the prefix and then write the ISBN attribute.
   String^ prefix = writer->LookupPrefix( "urn:samples" );
   writer->WriteStartAttribute( prefix, "ISBN", "urn:samples" );
   writer->WriteString( "1-861003-78" );
   writer->WriteEndAttribute();
   
   //Write the title.
   writer->WriteStartElement( "title" );
   writer->WriteString( "The Handmaid's Tale" );
   writer->WriteEndElement();
   
   //Write the price.
   writer->WriteElementString( "price", "19.95" );
   
   //Write the style element.
   writer->WriteStartElement( prefix, "style", "urn:samples" );
   writer->WriteString( "hardcover" );
   writer->WriteEndElement();
   
   //Write the end tag for the book element.
   writer->WriteEndElement();
   
   //Write the close tag for the root element.
   writer->WriteEndElement();
   
   //Write the XML to file and close the writer.
   writer->Flush();
   writer->Close();
   
   //Read the file back in and parse to ensure well formed XML.
   XmlDocument^ doc = gcnew XmlDocument;
   
   //Preserve white space for readability.
   doc->PreserveWhitespace = true;
   
   //Load the file
   doc->Load( filename );
   
   //Write the XML content to the console.
   Console::Write( doc->InnerXml );
}

using System;
using System.IO;
using System.Xml;

public class Sample
{
  private const string filename = "sampledata.xml";

  public static void Main()
  {

     XmlTextWriter writer = new XmlTextWriter (filename, null);
     //Use indenting for readability.
     writer.Formatting = Formatting.Indented;

     writer.WriteComment("sample XML fragment");

     //Write an element (this one is the root).
     writer.WriteStartElement("bookstore");

     //Write the namespace declaration.
     writer.WriteAttributeString("xmlns", "bk", null, "urn:samples");

     writer.WriteStartElement("book");

     //Lookup the prefix and then write the ISBN attribute.
     string prefix = writer.LookupPrefix("urn:samples");
     writer.WriteStartAttribute(prefix, "ISBN", "urn:samples");
     writer.WriteString("1-861003-78");
     writer.WriteEndAttribute();

     //Write the title.
     writer.WriteStartElement("title");
     writer.WriteString("The Handmaid's Tale");
     writer.WriteEndElement();

     //Write the price.
     writer.WriteElementString("price", "19.95");

     //Write the style element.
     writer.WriteStartElement(prefix, "style", "urn:samples");
     writer.WriteString("hardcover");
     writer.WriteEndElement();

     //Write the end tag for the book element.
     writer.WriteEndElement();

     //Write the close tag for the root element.
     writer.WriteEndElement();

     //Write the XML to file and close the writer.
     writer.Flush();
     writer.Close();

     //Read the file back in and parse to ensure well formed XML.
     XmlDocument doc = new XmlDocument();
     //Preserve white space for readability.
     doc.PreserveWhitespace = true;
     //Load the file
     doc.Load(filename);

     //Write the XML content to the console.
     Console.Write(doc.InnerXml);
  }
}

Option Strict
Option Explicit

Imports System.IO
Imports System.Xml

Public Class Sample
    Private Shared filename As String = "sampledata.xml"
    Public Shared Sub Main()
        
        Dim writer As New XmlTextWriter(filename, Nothing)
        'Use indenting for readability.
        writer.Formatting = Formatting.Indented
        
        writer.WriteComment("sample XML fragment")
        
        'Write an element (this one is the root).
        writer.WriteStartElement("bookstore")
        
        'Write the namespace declaration.
        writer.WriteAttributeString("xmlns", "bk", Nothing, "urn:samples")
        
        writer.WriteStartElement("book")
        
        'Lookup the prefix and then write the ISBN attribute.
        Dim prefix As String = writer.LookupPrefix("urn:samples")
        writer.WriteStartAttribute(prefix, "ISBN", "urn:samples")
        writer.WriteString("1-861003-78")
        writer.WriteEndAttribute()
        
        'Write the title.
        writer.WriteStartElement("title")
        writer.WriteString("The Handmaid's Tale")
        writer.WriteEndElement()
        
        'Write the price.
        writer.WriteElementString("price", "19.95")
        
        'Write the style element.
        writer.WriteStartElement(prefix, "style", "urn:samples")
        writer.WriteString("hardcover")
        writer.WriteEndElement()
        
        'Write the end tag for the book element.
        writer.WriteEndElement()
        
        'Write the close tag for the root element.
        writer.WriteEndElement()
        
        'Write the XML to file and close the writer.
        writer.Flush()
        writer.Close()
        
        'Read the file back in and parse to ensure well formed XML.
        Dim doc As New XmlDocument()
        'Preserve white space for readability.
        doc.PreserveWhitespace = True
        'Load the file.
        doc.Load(filename)
        
        'Write the XML content to the console.
        Console.Write(doc.InnerXml)
    End Sub
End Class

Remarques

Notes

À compter de .NET Framework 2.0, nous vous recommandons de créer XmlWriter des instances à l’aide de la XmlWriter.Create méthode et de la XmlWriterSettings classe pour tirer parti des nouvelles fonctionnalités.