XmlTextReader.ReadBase64(Byte[], Int32, Int32) Méthode

Définition

Espace de noms:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlTextReader.cs

Décode Base64 et retourne les octets binaires décodés.

public:
 int ReadBase64(cli::array <System::Byte> ^ array, int offset, int len);

public int ReadBase64 (byte[] array, int offset, int len);

member this.ReadBase64 : byte[] * int * int -> int

Public Function ReadBase64 (array As Byte(), offset As Integer, len As Integer) As Integer

Paramètres

array

Byte[]

Tableau de caractères servant de mémoire tampon dans laquelle le texte est écrit.

offset

Int32

Index de base zéro dans le tableau spécifiant à partir d'où la méthode peut écrire dans la mémoire tampon.

len

Int32

Nombre d'octets à écrire dans la mémoire tampon.

Retours

Int32

Nombre d'octets écrits dans la mémoire tampon.

Exceptions

XmlException

La séquence Base64 est non valide.

ArgumentNullException

La valeur de array est null.

ArgumentOutOfRangeException

offset < 0, ou len< 0, ou len>array.Length- offset.

Exemples

L’exemple suivant lit un fichier contenant des données Base64 et BinHex.

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   String^ filename = "binary.xml";
   try
   {
      reader = gcnew XmlTextReader( filename );
      reader->WhitespaceHandling = WhitespaceHandling::None;
      
      // Read the file. Stop at the Base64 element.
      while ( reader->Read() )
      {
         if ( "Base64" == reader->Name )
                  break;
      }
      
      // Read the Base64 data. Write the decoded 
      // bytes to the console.
      Console::WriteLine( "Reading Base64... " );
      int base64len = 0;
      array<Byte>^base64 = gcnew array<Byte>(1000);
      do
      {
         base64len = reader->ReadBase64( base64, 0, 50 );
         for ( int i = 0; i < base64len; i++ )
            Console::Write( base64[ i ] );
      }
      while ( reader->Name->Equals( "Base64" ) );
      
      // Read the BinHex data. Write the decoded 
      // bytes to the console.
      Console::WriteLine( "\r\nReading BinHex..." );
      int binhexlen = 0;
      array<Byte>^binhex = gcnew array<Byte>(1000);
      do
      {
         binhexlen = reader->ReadBinHex( binhex, 0, 50 );
         for ( int i = 0; i < binhexlen; i++ )
            Console::Write( binhex[ i ] );
      }
      while ( reader->Name->Equals( "BinHex" ) );
   }
   finally
   {
      Console::WriteLine();
      Console::WriteLine( "Processing of the file {0} complete.", filename );
      if ( reader != nullptr )
            reader->Close();
   }

}

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

public class Sample {

  private const string filename = "binary.xml";

  public static void Main() {

     XmlTextReader reader = null;

     try {

        reader = new XmlTextReader(filename);
        reader.WhitespaceHandling = WhitespaceHandling.None;

        // Read the file. Stop at the Base64 element.
        while (reader.Read()) {
           if ("Base64" == reader.Name) break;
        }
            
        // Read the Base64 data. Write the decoded
        // bytes to the console.
        Console.WriteLine("Reading Base64... ");
        int base64len = 0;
        byte[] base64 = new byte[1000];
        do {
           base64len = reader.ReadBase64(base64, 0, 50);
           for (int i=0; i < base64len; i++) Console.Write(base64[i]);
        } while (reader.Name == "Base64");
    
        // Read the BinHex data. Write the decoded
        // bytes to the console.
        Console.WriteLine("\r\nReading BinHex...");
        int binhexlen = 0;
        byte[] binhex = new byte[1000];
        do {
           binhexlen = reader.ReadBinHex(binhex, 0, 50);
           for (int i=0; i < binhexlen; i++) Console.Write(binhex[i]);
        }  while (reader.Name == "BinHex");
     }

     finally {
        Console.WriteLine();
        Console.WriteLine("Processing of the file {0} complete.", filename);
        if (reader != null)
          reader.Close();
     }
  }
}

Option Explicit
Option Strict

Imports System.IO
Imports System.Xml

Public Class Sample
   Private Const filename As String = "binary.xml"
   
   
   Public Shared Sub Main()
      Dim reader As XmlTextReader = Nothing
      Dim i As Integer

      Try
         reader = New XmlTextReader(filename)
         reader.WhitespaceHandling = WhitespaceHandling.None         

         ' Read the file. Stop at the Base64 element.         
         While reader.Read()
            If "Base64" = reader.Name Then
               Exit While
            End If
         End While 

         ' Read the Base64 data. Write the decoded 
         ' bytes to the console.
         Console.WriteLine("Reading base64... ")
         Dim base64len As Integer = 0
         Dim base64(1000) As Byte
         Do
            base64len = reader.ReadBase64(base64, 0, 50)
            For i = 0 To base64len - 1
               Console.Write(base64(i))
            Next i
         Loop While (reader.Name = "Base64")

         ' Read the BinHex data. Write the decoded 
         ' bytes to the console.
         Console.WriteLine(ControlChars.CrLf & "Reading binhex....")
         Dim binhexlen As Integer = 0
         Dim binhex(1000) As Byte
         binhexlen = reader.ReadBinHex(binhex, 0, 50)
         Do
            binhexlen = reader.ReadBinHex(binhex, 0, 50)
            For i = 0 To binhexlen - 1
               Console.Write(binhex(i))
            Next i
         Loop While (reader.Name = "BinHex") 
      
      Finally
         Console.WriteLine()
         Console.WriteLine("Processing of the file {0} complete.", filename)
         If Not (reader Is Nothing) Then
            reader.Close()
         End If
      End Try
   End Sub
End Class

L’exemple utilise le fichier binary.xml

<data>
<!-- sample data for base64 and binhex -->
<Base64>AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS
4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFi
Y2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlp
eYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrL
zM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w
==</Base64>
<BinHex>000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E
1F202122232425262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E3F4041
42434445464748494A4B4C4D4E4F505152535455565758595A5B5C5D5E5F6061626364
65666768696A6B6C6D6E6F707172737475767778797A7B7C7D7E7F8081828384858687
88898A8B8C8D8E8F909192939495969798999A9B9C9D9E9FA0A1A2A3A4A5A6A7A8A9AA
ABACADAEAFB0B1B2B3B4B5B6B7B8B9BABBBCBDBEBFC0C1C2C3C4C5C6C7C8C9CACBCCCD
CECFD0D1D2D3D4D5D6D7D8D9DADBDCDDDEDFE0E1E2E3E4E5E6E7E8E9EAEBECEDEEEFF0
F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF</BinHex>
</data>

Remarques

Notes

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

Comme ReadChars, cette méthode peut être appelée successivement pour lire de grands flux de texte incorporé. Il décode le contenu base64 et retourne les octets binaires décodés (par exemple, une image GIF encodée en ligne en Base64) dans la mémoire tampon. Voir RFC 1521. (Vous pouvez obtenir des RFC à partir du site Web de demande de commentaires.)

Voir aussi

• WriteBase64(Byte[], Int32, Int32)
• XmlReader