Encoder Classe

Définition

public ref class Encoder abstract

public abstract class Encoder

[System.Serializable]
public abstract class Encoder

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class Encoder

type Encoder = class

[<System.Serializable>]
type Encoder = class

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type Encoder = class

Public MustInherit Class Encoder

Héritage

Object

Encoder

Attributs

SerializableAttribute ComVisibleAttribute

Exemples

L’exemple suivant montre comment convertir un tableau de caractères Unicode en blocs d’octets à l’aide d’un encodage spécifié. À des fins de comparaison, le tableau de caractères est d’abord encodé à l’aide de UTF7Encoding. Ensuite, le tableau de caractères est encodé à l’aide d’un Encoder.

using namespace System;
using namespace System::Text;
using namespace System::Collections;
void ShowArray( Array^ theArray )
{
   IEnumerator^ myEnum = theArray->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ o = safe_cast<Object^>(myEnum->Current);
      Console::Write( "[{0}]", o );
   }

   Console::WriteLine( "\n" );
}

int main()
{
   
   // The characters to encode.
   
   // Pi
   // Sigma
   array<Char>^chars = {L'\u03a0',L'\u03a3',L'\u03a6',L'\u03a9'};
   
   // Encode characters using an Encoding Object*.
   Encoding^ encoding = Encoding::UTF7;
   Console::WriteLine( "Using Encoding\n--------------" );
   
   // Encode complete array for comparison.
   array<Byte>^allCharactersFromEncoding = encoding->GetBytes( chars );
   Console::WriteLine( "All characters encoded:" );
   ShowArray( allCharactersFromEncoding );
   
   // Encode characters, one-by-one.
   // The Encoding Object* will NOT maintain state between calls.
   array<Byte>^firstchar = encoding->GetBytes( chars, 0, 1 );
   Console::WriteLine( "First character:" );
   ShowArray( firstchar );
   array<Byte>^secondchar = encoding->GetBytes( chars, 1, 1 );
   Console::WriteLine( "Second character:" );
   ShowArray( secondchar );
   array<Byte>^thirdchar = encoding->GetBytes( chars, 2, 1 );
   Console::WriteLine( "Third character:" );
   ShowArray( thirdchar );
   array<Byte>^fourthchar = encoding->GetBytes( chars, 3, 1 );
   Console::WriteLine( "Fourth character:" );
   ShowArray( fourthchar );
   
   // Now, encode characters using an Encoder Object*.
   Encoder^ encoder = encoding->GetEncoder();
   Console::WriteLine( "Using Encoder\n-------------" );
   
   // Encode complete array for comparison.
   array<Byte>^allCharactersFromEncoder = gcnew array<Byte>(encoder->GetByteCount( chars, 0, chars->Length, true ));
   encoder->GetBytes( chars, 0, chars->Length, allCharactersFromEncoder, 0, true );
   Console::WriteLine( "All characters encoded:" );
   ShowArray( allCharactersFromEncoder );
   
   // Do not flush state; i.e. maintain state between calls.
   bool bFlushState = false;
   
   // Encode characters one-by-one.
   // By maintaining state, the Encoder will not store extra bytes in the output.
   array<Byte>^firstcharNoFlush = gcnew array<Byte>(encoder->GetByteCount( chars, 0, 1, bFlushState ));
   encoder->GetBytes( chars, 0, 1, firstcharNoFlush, 0, bFlushState );
   Console::WriteLine( "First character:" );
   ShowArray( firstcharNoFlush );
   array<Byte>^secondcharNoFlush = gcnew array<Byte>(encoder->GetByteCount( chars, 1, 1, bFlushState ));
   encoder->GetBytes( chars, 1, 1, secondcharNoFlush, 0, bFlushState );
   Console::WriteLine( "Second character:" );
   ShowArray( secondcharNoFlush );
   array<Byte>^thirdcharNoFlush = gcnew array<Byte>(encoder->GetByteCount( chars, 2, 1, bFlushState ));
   encoder->GetBytes( chars, 2, 1, thirdcharNoFlush, 0, bFlushState );
   Console::WriteLine( "Third character:" );
   ShowArray( thirdcharNoFlush );
   
   // Must flush state on last call to GetBytes().
   bFlushState = true;
   array<Byte>^fourthcharNoFlush = gcnew array<Byte>(encoder->GetByteCount( chars, 3, 1, bFlushState ));
   encoder->GetBytes( chars, 3, 1, fourthcharNoFlush, 0, bFlushState );
   Console::WriteLine( "Fourth character:" );
   ShowArray( fourthcharNoFlush );
}

/* This code example produces the following output.

Using Encoding
--------------
All characters encoded:
[43][65][54][65][68][111][119][79][109][65][54][107][45]

First character:
[43][65][54][65][45]

Second character:
[43][65][54][77][45]

Third character:
[43][65][54][89][45]

Fourth character:
[43][65][54][107][45]

Using Encoder
-------------
All characters encoded:
[43][65][54][65][68][111][119][79][109][65][54][107][45]

First character:
[43][65][54]

Second character:
[65][68][111]

Third character:
[119][79][109]

Fourth character:
[65][54][107][45]


*/

using System;
using System.Text;

class EncoderTest {
    public static void Main() {
        // The characters to encode.
        Char[] chars = new Char[] {
            '\u0023', // #
            '\u0025', // %
            '\u03a0', // Pi
            '\u03a3'  // Sigma
        };

        // Encode characters using an Encoding object.
        Encoding encoding = Encoding.UTF7;
        Console.WriteLine("Using Encoding\n--------------");

        // Encode complete array for comparison.
        Byte[] allCharactersFromEncoding = encoding.GetBytes(chars);
        Console.WriteLine("All characters encoded:");
        ShowArray(allCharactersFromEncoding);

        // Encode characters, one-by-one.
        // The Encoding object will NOT maintain state between calls.
        Byte[] firstchar = encoding.GetBytes(chars, 0, 1);
        Console.WriteLine("First character:");
        ShowArray(firstchar);

        Byte[] secondchar = encoding.GetBytes(chars, 1, 1);
        Console.WriteLine("Second character:");
        ShowArray(secondchar);

        Byte[] thirdchar = encoding.GetBytes(chars, 2, 1);
        Console.WriteLine("Third character:");
        ShowArray(thirdchar);

        Byte[] fourthchar = encoding.GetBytes(chars, 3, 1);
        Console.WriteLine("Fourth character:");
        ShowArray(fourthchar);

        // Now, encode characters using an Encoder object.
        Encoder encoder = encoding.GetEncoder();
        Console.WriteLine("Using Encoder\n-------------");

        // Encode complete array for comparison.
        Byte[] allCharactersFromEncoder = new Byte[encoder.GetByteCount(chars, 0, chars.Length, true)];
        encoder.GetBytes(chars, 0, chars.Length, allCharactersFromEncoder, 0, true);
        Console.WriteLine("All characters encoded:");
        ShowArray(allCharactersFromEncoder);

        // Do not flush state; i.e. maintain state between calls.
        bool bFlushState = false;

        // Encode characters one-by-one.
        // By maintaining state, the Encoder will not store extra bytes in the output.
        Byte[] firstcharNoFlush = new Byte[encoder.GetByteCount(chars, 0, 1, bFlushState)];
        encoder.GetBytes(chars, 0, 1, firstcharNoFlush, 0, bFlushState);
        Console.WriteLine("First character:");
        ShowArray(firstcharNoFlush);

        Byte[] secondcharNoFlush = new Byte[encoder.GetByteCount(chars, 1, 1, bFlushState)];
        encoder.GetBytes(chars, 1, 1, secondcharNoFlush, 0, bFlushState);
        Console.WriteLine("Second character:");
        ShowArray(secondcharNoFlush);

        Byte[] thirdcharNoFlush = new Byte[encoder.GetByteCount(chars, 2, 1, bFlushState)];
        encoder.GetBytes(chars, 2, 1, thirdcharNoFlush, 0, bFlushState);
        Console.WriteLine("Third character:");
        ShowArray(thirdcharNoFlush);

        // Must flush state on last call to GetBytes().
        bFlushState = true;
        
        Byte[] fourthcharNoFlush = new Byte[encoder.GetByteCount(chars, 3, 1, bFlushState)];
        encoder.GetBytes(chars, 3, 1, fourthcharNoFlush, 0, bFlushState);
        Console.WriteLine("Fourth character:");
        ShowArray(fourthcharNoFlush);
    }

    public static void ShowArray(Array theArray) {
        foreach (Object o in theArray) {
            Console.Write("[{0}]", o);
        }
        Console.WriteLine("\n");
    }
}

/* This code example produces the following output.

Using Encoding
--------------
All characters encoded:
[43][65][67][77][65][74][81][79][103][65][54][77][45]

First character:
[43][65][67][77][45]

Second character:
[43][65][67][85][45]

Third character:
[43][65][54][65][45]

Fourth character:
[43][65][54][77][45]

Using Encoder
-------------
All characters encoded:
[43][65][67][77][65][74][81][79][103][65][54][77][45]

First character:
[43][65][67]

Second character:
[77][65][74]

Third character:
[81][79][103]

Fourth character:
[65][54][77][45]


*/

Imports System.Text
Imports Microsoft.VisualBasic.Strings

Class EncoderTest
    
    Public Shared Sub Main()
        ' Unicode characters.
        ' ChrW(35)  = #
        ' ChrW(37)  = %
        ' ChrW(928) = Pi
        ' ChrW(931) = Sigma
        Dim chars() As Char = {ChrW(35), ChrW(37), ChrW(928), ChrW(931)}
        
        ' Encode characters using an Encoding object.
        Dim encoding As Encoding = Encoding.UTF7
        Console.WriteLine( _
            "Using Encoding" & _
            ControlChars.NewLine & _
            "--------------" _
        )
        
        ' Encode complete array for comparison.
        Dim allCharactersFromEncoding As Byte() = encoding.GetBytes(chars)
        Console.WriteLine("All characters encoded:")
        ShowArray(allCharactersFromEncoding)
        
        ' Encode characters, one-by-one.
        ' The Encoding object will NOT maintain state between calls.
        Dim firstchar As Byte() = encoding.GetBytes(chars, 0, 1)
        Console.WriteLine("First character:")
        ShowArray(firstchar)
        
        Dim secondchar As Byte() = encoding.GetBytes(chars, 1, 1)
        Console.WriteLine("Second character:")
        ShowArray(secondchar)
        
        Dim thirdchar As Byte() = encoding.GetBytes(chars, 2, 1)
        Console.WriteLine("Third character:")
        ShowArray(thirdchar)
        
        Dim fourthchar As Byte() = encoding.GetBytes(chars, 3, 1)
        Console.WriteLine("Fourth character:")
        ShowArray(fourthchar)
        
        
        ' Now, encode characters using an Encoder object.
        Dim encoder As Encoder = encoding.GetEncoder()
        Console.WriteLine( _
            "Using Encoder" & _
            ControlChars.NewLine & _
            "-------------" _
        )
        
        ' Encode complete array for comparison.
        Dim allCharactersFromEncoder( _
            encoder.GetByteCount(chars, 0, chars.Length, True) _
        ) As Byte
        encoder.GetBytes(chars, 0, chars.Length, allCharactersFromEncoder, 0, True)
        Console.WriteLine("All characters encoded:")
        ShowArray(allCharactersFromEncoder)
        
        ' Do not flush state; i.e. maintain state between calls.
        Dim bFlushState As Boolean = False
        
        ' Encode characters one-by-one.
        ' By maintaining state, the Encoder will not store extra bytes in the output.
        Dim firstcharNoFlush( _
            encoder.GetByteCount(chars, 0, 1, bFlushState) _
        ) As Byte
        encoder.GetBytes(chars, 0, 1, firstcharNoFlush, 0, bFlushState)
        Console.WriteLine("First character:")
        ShowArray(firstcharNoFlush)
        
        Dim secondcharNoFlush( _
            encoder.GetByteCount(chars, 1, 1, bFlushState) _
        ) As Byte
        encoder.GetBytes(chars, 1, 1, secondcharNoFlush, 0, bFlushState)
        Console.WriteLine("Second character:")
        ShowArray(secondcharNoFlush)
        
        Dim thirdcharNoFlush( _
            encoder.GetByteCount(chars, 2, 1, bFlushState) _
        ) As Byte
        encoder.GetBytes(chars, 2, 1, thirdcharNoFlush, 0, bFlushState)
        Console.WriteLine("Third character:")
        ShowArray(thirdcharNoFlush)
        
        ' Must flush state on last call to GetBytes().
        bFlushState = True
        
        Dim fourthcharNoFlush( _
            encoder.GetByteCount(chars, 3, 1, bFlushState) _
        ) As Byte
        encoder.GetBytes(chars, 3, 1, fourthcharNoFlush, 0, bFlushState)
        Console.WriteLine("Fourth character:")
        ShowArray(fourthcharNoFlush)
    End Sub
    
    
    Public Shared Sub ShowArray(theArray As Array)
        Dim o As Object
        For Each o In  theArray
            Console.Write("[{0}]", o)
        Next o
        Console.WriteLine(ControlChars.NewLine)
    End Sub
End Class

'This code example produces the following output.
'
'Using Encoding
'--------------
'All characters encoded:
'[43][65][67][77][65][74][81][79][103][65][54][77][45]
'
'First character:
'[43][65][67][77][45]
'
'Second character:
'[43][65][67][85][45]
'
'Third character:
'[43][65][54][65][45]
'
'Fourth character:
'[43][65][54][77][45]
'
'Using Encoder
'-------------
'All characters encoded:
'[43][65][67][77][65][74][81][79][103][65][54][77][45][0]
'
'First character:
'[43][65][67][0]
'
'Second character:
'[77][65][74][0]
'
'Third character:
'[81][79][103][0]
'
'Fourth character:
'[65][54][77][45][0]
'

Remarques

Pour obtenir une instance d’une implémentation de la Encoder classe , l’application doit utiliser la GetEncoder méthode d’une Encoding implémentation.

La GetByteCount méthode détermine le nombre d’octets entraînant l’encodage d’un jeu de caractères Unicode, et la GetBytes méthode effectue l’encodage réel. Plusieurs versions de ces deux méthodes sont disponibles dans la Encoder classe . Pour plus d'informations, consultez Encoding.GetBytes.

Un Encoder objet conserve les informations d’état entre les appels successifs aux GetBytes méthodes ou Convert afin qu’il puisse encoder correctement des séquences de caractères qui s’étendent sur des blocs. Le Encoder conserve également les caractères de fin à la fin des blocs de données et utilise les caractères de fin dans l’opération d’encodage suivante. Par exemple, un bloc de données peut se terminer par un substitut étendu sans correspondance, et le substitut faible correspondant peut se trouver dans le bloc de données suivant. Par conséquent, GetDecoder et GetEncoder sont utiles pour la transmission réseau et les opérations de fichier, car ces opérations traitent souvent des blocs de données au lieu d’un flux de données complet.

Notes pour les responsables de l’implémentation

Lorsque votre application hérite de cette classe, elle doit remplacer tous les membres.

Constructeurs

Propriétés

Méthodes

Méthodes d’extension

S’applique à

Voir aussi

• Decoder
• Encoding
• Fonctionnement des encodages