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

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Definition

Namespace:
System.Xml
Assembly:
System.Xml.ReaderWriter.dll
Assembly:
System.Xml.dll
Assembly:
netstandard.dll

Decodiert Base64 und gibt die decodierten Binärbytes zurück.

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

Parameter

array
Byte[]

Das Array von Zeichen, das als Puffer dient, in den der Textinhalt geschrieben wird.

offset
Int32

Der nullbasierte Index im Array, der angibt, an welcher Position die Methode mit dem Schreiben in den Puffer beginnen kann.

len
Int32

Die Anzahl der in den Puffer zu schreibenden Bytes.

Gibt zurück

Int32

Die Anzahl der in den Puffer geschriebenen Bytes.

Ausnahmen

XmlException

Die Base64-Sequenz ist ungültig.

ArgumentNullException

Der Wert von array ist null.

ArgumentOutOfRangeException

offset < 0 oder len < 0 oder len > array.Length- offset.

Beispiele

Im folgenden Beispiel wird eine Datei mit Base64- und BinHex-Daten gelesen.

#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

Das Beispiel verwendet die Datei 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>

Hinweise

Hinweis

Ab dem .NET Framework 2.0 empfehlen wir, Instanzen mithilfe der XmlReader.Create Methode zu erstellenXmlReader, um neue Funktionen zu nutzen.

Wie folgt ReadCharskann diese Methode aufgerufen werden, um große Datenströme von eingebetteten Text zu lesen. Es decodest Base64-Inhalt und gibt die dekodierten binär bytes (z. B. ein inline Base64 codiertes GIF-Bild) in den Puffer zurück. Siehe RFC 1521. (Sie können RFCs aus der Website "Kommentare anfordern" abrufen.)

Gilt für

Siehe auch