XmlTextWriter.LookupPrefix メソッド

.NET Framework クラス ライブラリ リファレンス

XmlTextWriter.LookupPrefix メソッド

名前空間 URI の現在の名前空間スコープで定義されたものに最も近いプリフィックスを返します。

名前空間: System.Xml
アセンブリ: System.Xml (system.xml.dll 内)
構文

Visual Basic (宣言)

Public Overrides Function
 LookupPrefix ( _
    ns As String _
) As String

Visual Basic (使用法)

Dim instance As XmlTextWriter
Dim ns As String
Dim returnValue As String

returnValue = instance.LookupPrefix(ns)

C#

public override string LookupPrefix (
    string ns
)

C++

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

J#

public String LookupPrefix (
    String ns
)

JScript

public override function LookupPrefix (
    ns : String
) : String

パラメータ

ns

検索する対象となるプリフィックスを持つ名前空間 URI。

戻り値
一致するプリフィックス。一致する名前空間 URI が現在のスコープで見つからない場合は null 参照 (Visual Basic では Nothing)。

例外

例外の種類	条件
ArgumentException	ns が null 参照 (Visual Basic では Nothing) または String.Empty のいずれかです。

解説

メモ
Microsoft .NET Framework version 2.0 リリースでは、System.Xml.XmlWriter.Create メソッドと XmlWriterSettings クラスを使用して XmlWriter インスタンスを作成することをお勧めします。これにより、このリリースで導入されたすべての新機能を十分に活用できます。詳細については、「XML ライタの作成」を参照してください。

使用例

book を書き込む例を次に示します。

Visual Basic

Option Strict
Option Explicit

Imports System
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 'Main 
End Class 'Sample

C#

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);  

  }

}

C++

#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 );
}

J#

import System.*;
import System.IO.*;
import System.Xml.*;

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

    public static void main(String[]
 args)
    {
        XmlTextWriter writer = new XmlTextWriter(fileName, null);

        //Use indenting for readability.
        writer.set_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.set_PreserveWhitespace(true);

        //Load the file
        doc.Load(fileName);

        //Write the XML content to the console.
        Console.Write(doc.get_InnerXml());
    } //main 
} //Sample

プラットフォーム

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

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0
.NET Compact Framework
サポート対象 : 2.0、1.0

参照

関連項目
XmlTextWriter クラス
XmlTextWriter メンバ
System.Xml 名前空間