XmlWriter.LookupPrefix(String) Methode

Definition

Namespace:
System.Xml
Assemblys:
System.Xml.dll, System.Xml.ReaderWriter.dll
Assemblys:
netstandard.dll, System.Xml.ReaderWriter.dll
Assembly:
System.Xml.ReaderWriter.dll
Assembly:
System.Xml.dll
Assembly:
netstandard.dll
Quelle:
XmlWriter.cs
Quelle:
XmlWriter.cs
Quelle:
XmlWriter.cs
Quelle:
XmlWriter.cs
Quelle:
XmlWriter.cs

Wenn sie in einer abgeleiteten Klasse überschrieben wird, wird das im aktuellen Namespacebereich für den Namespace-URI definierte präfix zurückgegeben.

public:
 abstract System::String ^ LookupPrefix(System::String ^ ns);
public abstract string LookupPrefix(string ns);
public abstract string? LookupPrefix(string ns);
abstract member LookupPrefix : string -> string
Public MustOverride Function LookupPrefix (ns As String) As String

Parameter

ns
String

Der Namespace-URI, dessen Präfix Sie suchen möchten.

Gibt zurück

String

Das übereinstimmende Präfix oder null wenn im aktuellen Bereich kein übereinstimmener Namespace-URI gefunden wird.

Ausnahmen

ArgumentException

ns ist entweder null oder String.Empty.

InvalidOperationException

Eine XmlWriter Methode wurde aufgerufen, bevor ein vorheriger asynchroner Vorgang abgeschlossen wurde. In diesem Fall InvalidOperationException wird die Meldung "Ein asynchroner Vorgang wird bereits ausgeführt" ausgelöst.

Beispiele

Im folgenden Beispiel wird ein Buch geschrieben.

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, settings);

        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();
     }
   }
 }

Option Strict
Option Explicit

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, settings)
            
        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
End Class

Gilt für: