Decoder.Convert Decoder.Convert Decoder.Convert Decoder.Convert Method

Definición

Convierte una secuencia de bytes codificada en una cadena o matriz de caracteres.Converts an encoded byte sequence to a string or array of characters.

Sobrecargas

Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean)
Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean)

Convierte un búfer de bytes codificados en caracteres con codificación UTF-16 y almacena el resultado en otro búfer.Converts a buffer of encoded bytes to UTF-16 encoded characters and stores the result in another buffer.

Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean)

Convierte una matriz de bytes codificados en caracteres con codificación UTF-16 y almacena el resultado en otra matriz de caracteres.Converts an array of encoded bytes to UTF-16 encoded characters and stores the result in a character array.

Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean) Convert(ReadOnlySpan<Byte>, Span<Char>, Boolean, Int32, Int32, Boolean)

public:
 virtual void Convert(ReadOnlySpan<System::Byte> bytes, Span<char> chars, bool flush, [Runtime::InteropServices::Out] int % bytesUsed, [Runtime::InteropServices::Out] int % charsUsed, [Runtime::InteropServices::Out] bool % completed);
public virtual void Convert (ReadOnlySpan<byte> bytes, Span<char> chars, bool flush, out int bytesUsed, out int charsUsed, out bool completed);
abstract member Convert : ReadOnlySpan<byte> * Span<char> * bool *  *  *  -> unit
override this.Convert : ReadOnlySpan<byte> * Span<char> * bool *  *  *  -> unit
Public Overridable Sub Convert (bytes As ReadOnlySpan(Of Byte), chars As Span(Of Char), flush As Boolean, ByRef bytesUsed As Integer, ByRef charsUsed As Integer, ByRef completed As Boolean)

Parámetros

chars
Span<Char>
bytesUsed
Int32 Int32 Int32 Int32
charsUsed
Int32 Int32 Int32 Int32

Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte*, Int32, Char*, Int32, Boolean, Int32, Int32, Boolean)

Importante

Esta API no es conforme a CLS.

Alternativa conforme a CLS
System.Text.Decoder.Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean)

Convierte un búfer de bytes codificados en caracteres con codificación UTF-16 y almacena el resultado en otro búfer.Converts a buffer of encoded bytes to UTF-16 encoded characters and stores the result in another buffer.

public:
 virtual void Convert(System::Byte* bytes, int byteCount, char* chars, int charCount, bool flush, [Runtime::InteropServices::Out] int % bytesUsed, [Runtime::InteropServices::Out] int % charsUsed, [Runtime::InteropServices::Out] bool % completed);
[System.CLSCompliant(false)]
[System.Runtime.InteropServices.ComVisible(false)]
[System.Security.SecurityCritical]
public virtual void Convert (byte* bytes, int byteCount, char* chars, int charCount, bool flush, out int bytesUsed, out int charsUsed, out bool completed);
abstract member Convert : nativeptr<byte> * int * nativeptr<char> * int * bool *  *  *  -> unit
override this.Convert : nativeptr<byte> * int * nativeptr<char> * int * bool *  *  *  -> unit

Parámetros

bytes
Byte*

Dirección de un búfer que contiene las secuencias de bytes que convertir.The address of a buffer that contains the byte sequences to convert.

byteCount
Int32 Int32 Int32 Int32

Número de bytes en bytes que se va a convertir.The number of bytes in bytes to convert.

chars
Char*

Dirección de un búfer donde se van a almacenar los caracteres convertidos.The address of a buffer to store the converted characters.

charCount
Int32 Int32 Int32 Int32

Número máximo de caracteres en chars que se puede usar en la conversión.The maximum number of characters in chars to use in the conversion.

flush
Boolean Boolean Boolean Boolean

true para indicar que no se van a convertir más datos; de lo contrario, false.true to indicate no further data is to be converted; otherwise, false.

bytesUsed
Int32 Int32 Int32 Int32

Cuando este método vuelve, contiene el número de bytes que la conversión ha generado.When this method returns, contains the number of bytes that were produced by the conversion. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

charsUsed
Int32 Int32 Int32 Int32

Cuando este método vuelve, contiene el número de caracteres de chars que se usaron en la conversión.When this method returns, contains the number of characters from chars that were used in the conversion. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

completed
Boolean Boolean Boolean Boolean

Cuando este método vuelve, contiene true si todos los caracteres especificados por byteCount se han convertido; de lo contrario, false.When this method returns, contains true if all the characters specified by byteCount were converted; otherwise, false. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

Excepciones

chars o bytes es null (Nothing).chars or bytes is null (Nothing).

charCount o byteCount es menor que cero.charCount or byteCount is less than zero.

El búfer de salida es demasiado pequeño para contener la entrada convertida.The output buffer is too small to contain any of the converted input. El búfer de salida debe ser mayor o igual que el tamaño indicado por el método GetCharCount.The output buffer should be greater than or equal to the size indicated by the GetCharCount method.

Se ha producido una acción de reserva (vea Codificación de caracteres en .NET Framework para obtener una explicación completa)A fallback occurred (see Character Encoding in the .NET Framework for fuller explanation) - y --and- El valor de Fallback está establecido en DecoderExceptionFallback.Fallback is set to DecoderExceptionFallback.

Comentarios

Recuerde que el Decoder objeto guarda el estado entre las llamadas a Convert.Remember that the Decoder object saves state between calls to Convert. Cuando la aplicación se realiza con un flujo de datos, se debe establecer el flush parámetro true para asegurarse de que se vacíe la información de estado.When the application is done with a stream of data, it should set the flush parameter to true to make sure that the state information is flushed. Con esta configuración, el descodificador pasa por alto los bytes no válidos al final del bloque de datos y borra el búfer interno.With this setting, the decoder ignores invalid bytes at the end of the data block and clears the internal buffer. Los datos procesados restantes que forma parte de una unidad lógica, como suplente alto de un par suplente, se convierten según la configuración de reserva actual.Any remaining processed data that is part of a logical unit, such as the high surrogate of a surrogate pair, is converted according to the current fallback settings.

El Convert método está diseñado para usarse en un bucle para descodificar una cantidad arbitraria de entrada, como los datos leídos de un archivo o secuencia.The Convert method is designed to be used in a loop to decode an arbitrary amount of input, such as data read from a file or stream. Almacena el resultado de la operación de descodificación en un búfer de tamaño fijo.It stores the output of the decoding operation in a fixed-size buffer. GetChars se iniciará una excepción si el búfer de salida no es suficientemente grande, pero Convert se rellenará tanto espacio como sea posible y devolverá los bytes leídos y caracteres escritos.GetChars will throw an exception if the output buffer isn't large enough, but Convert will fill as much space as possible and return the bytes read and chars written. Consulte también el Encoding.GetChars tema para obtener más comentarios.Also see the Encoding.GetChars topic for more comments.

El completed parámetro de salida que indica si todos los datos en el búfer de entrada se convierten y se almacena en el búfer de salida.The completed output parameter indicates whether all the data in the input buffer was converted and stored in the output buffer. Este parámetro se establece en false si el número de bytes especificado por el byteCount parámetro no se puede convertir sin exceder el número de caracteres especificados por el charCount parámetro.This parameter is set to false if the number of bytes specified by the byteCount parameter cannot be converted without exceeding the number of characters specified by the charCount parameter. En esa situación, la aplicación debe usar el contenido del búfer de salida o proporcione un nuevo búfer de salida, incremento el bytes parámetro por el número de bytes especificado por el bytesUsed parámetro, a continuación, llame a la Convert método nuevo para procesar las entradas restantes.In that situation, the application should use the contents of the output buffer or provide a new output buffer, increment the bytes parameter by the number of bytes specified by the bytesUsed parameter, then call the Convert method again to process the remaining input.

El completed parámetro también se puede establecer en false, aunque el bytesUsed y byteCount parámetros son iguales.The completed parameter can also be set to false, even though the bytesUsed and byteCount parameters are equal. Esta situación se produce si todavía hay datos en el Decoder objeto que no se ha almacenado en el bytes búfer.This situation occurs if there is still data in the Decoder object that has not been stored in the bytes buffer.

Seguridad

SecurityCriticalAttribute
requiere plena confianza para el llamador inmediato.Requires full trust for the immediate caller. Este miembro no se puede usar código de confianza parcial o transparente.This member cannot be used by partially trusted or transparent code.

Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean) Convert(Byte[], Int32, Int32, Char[], Int32, Int32, Boolean, Int32, Int32, Boolean)

Convierte una matriz de bytes codificados en caracteres con codificación UTF-16 y almacena el resultado en otra matriz de caracteres.Converts an array of encoded bytes to UTF-16 encoded characters and stores the result in a character array.

public:
 virtual void Convert(cli::array <System::Byte> ^ bytes, int byteIndex, int byteCount, cli::array <char> ^ chars, int charIndex, int charCount, bool flush, [Runtime::InteropServices::Out] int % bytesUsed, [Runtime::InteropServices::Out] int % charsUsed, [Runtime::InteropServices::Out] bool % completed);
[System.Runtime.InteropServices.ComVisible(false)]
public virtual void Convert (byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex, int charCount, bool flush, out int bytesUsed, out int charsUsed, out bool completed);
abstract member Convert : byte[] * int * int * char[] * int * int * bool *  *  *  -> unit
override this.Convert : byte[] * int * int * char[] * int * int * bool *  *  *  -> unit
Public Overridable Sub Convert (bytes As Byte(), byteIndex As Integer, byteCount As Integer, chars As Char(), charIndex As Integer, charCount As Integer, flush As Boolean, ByRef bytesUsed As Integer, ByRef charsUsed As Integer, ByRef completed As Boolean)

Parámetros

bytes
Byte[]

Matriz de bytes para convertir.A byte array to convert.

byteIndex
Int32 Int32 Int32 Int32

Primer elemento de bytes que se va a convertir.The first element of bytes to convert.

byteCount
Int32 Int32 Int32 Int32

Número de elementos de bytes que se van a convertir.The number of elements of bytes to convert.

chars
Char[]

Matriz para almacenar los caracteres convertidos.An array to store the converted characters.

charIndex
Int32 Int32 Int32 Int32

El primer elemento de chars en el que se almacenan los datos.The first element of chars in which data is stored.

charCount
Int32 Int32 Int32 Int32

Número máximo de elementos de chars que se puede usar en la conversión.The maximum number of elements of chars to use in the conversion.

flush
Boolean Boolean Boolean Boolean

true para indicar que no se van a convertir más datos; de lo contrario, false.true to indicate that no further data is to be converted; otherwise, false.

bytesUsed
Int32 Int32 Int32 Int32

Cuando este método vuelve, contiene el número de bytes que se usaron en la conversión.When this method returns, contains the number of bytes that were used in the conversion. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

charsUsed
Int32 Int32 Int32 Int32

Cuando este método vuelve, contiene el número de caracteres de chars que se produjeron en la conversión.When this method returns, contains the number of characters from chars that were produced by the conversion. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

completed
Boolean Boolean Boolean Boolean

Cuando este método vuelve, contiene true si todos los caracteres especificados por byteCount se han convertido; de lo contrario, false.When this method returns, contains true if all the characters specified by byteCount were converted; otherwise, false. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

Excepciones

chars o bytes es null (Nothing).chars or bytes is null (Nothing).

charIndex, charCount, byteIndex o byteCount es menor que cero.charIndex, charCount, byteIndex, or byteCount is less than zero.

O bien-or- La longitud de chars - charIndex es menor que charCount.The length of chars - charIndex is less than charCount.

O bien-or- La longitud de bytes - byteIndex es menor que byteCount.The length of bytes - byteIndex is less than byteCount.

El búfer de salida es demasiado pequeño para contener la entrada convertida.The output buffer is too small to contain any of the converted input. El búfer de salida debe ser mayor o igual que el tamaño indicado por el método GetCharCount.The output buffer should be greater than or equal to the size indicated by the GetCharCount method.

Se ha producido una acción de reserva (vea Codificación de caracteres en .NET Framework para obtener una explicación completa)A fallback occurred (see Character Encoding in the .NET Framework for fuller explanation) - y --and- El valor de Fallback está establecido en DecoderExceptionFallback.Fallback is set to DecoderExceptionFallback.

Ejemplos

El siguiente ejemplo de código utiliza el Convert método para convertir un archivo de caracteres UTF-16 a UTF-8.The following code example uses the Convert method to convert a file of UTF-16 characters to UTF-8. A continuación, usa el Convert hacer una copia de método para convertir los caracteres UTF-8 a UTF-16 caracteres.It then uses the Convert method to convert the UTF-8 characters back to UTF-16 characters.

// This code example demonstrates the Encoder.Convert() and Decoder.Convert methods. 
// This example uses files for input and output, but any source that can be expressed
// as a stream can be used instead.

    using System;
    using System.Text;
    using System.IO;

    public class Sample
    {
    static void Main(string[] args)
        {
// Create a large file of UTF-16 encoded Unicode characters. The file is named Example.txt, 
// and is used as input to the Encoder.Convert() method. 

            CreateTestFile("Example.txt");

 
// Using an input file of UTF-16 encoded characters named Example.txt, create an output file 
// of UTF-8 encoded bytes named UTF8.txt.

            EncoderConvert("Example.txt", "UTF8.txt", Encoding.UTF8);

// Using an input file of UTF-8 encoded bytes named UTF8.txt, create an output file 
// of UTF-16 encoded characters named UTF16.txt.

            DecoderConvert("UTF8.txt", "UTF16.txt", Encoding.UTF8);
        }

// --------------------------------------------------------------------------------------------
// Use the Encoder.Convert() method to convert a file of characters to a file of encoded bytes.
// --------------------------------------------------------------------------------------------
        static void EncoderConvert(String inputFileName, String outputFileName, Encoding enc)
        {
// Convert an input file of characters to an output file of encoded bytes.
// StreamWriter could convert the input file for us, but we'll perform the conversion 
// ourselves.

            FileStream fs = new FileStream(outputFileName, FileMode.Create);
            BinaryWriter outputFile = new BinaryWriter(fs);

// StreamReader will detect Unicode encoding from the Byte Order Mark that heads the input file.
            StreamReader inputFile = new StreamReader(inputFileName);

// Get an Encoder.
            Encoder encoder = enc.GetEncoder();
            
// Guarantee the output buffer large enough to convert a few characters.
            int UseBufferSize = 64;
            if (UseBufferSize < enc.GetMaxByteCount(10))
                    UseBufferSize = enc.GetMaxByteCount(10);
            byte[] bytes = new byte[UseBufferSize];

// Intentionally make the input character buffer larger than the output byte buffer so the 
// conversion loop executes more than one cycle. 

            char[] chars = new char[UseBufferSize * 4];
            int charsRead;
            do
            {
// Read at most the number of characters that will fit in the input buffer. The return 
// value is the actual number of characters read, or zero if no characters remain. 
                charsRead = inputFile.Read(chars, 0, UseBufferSize * 4);
   
                bool completed = false;
                int charIndex = 0;
                int charsUsed;
                int bytesUsed;

                while (!completed)
                {
// If this is the last input data, flush the encoder's internal buffer and state.

                    bool flush = (charsRead == 0);
                    encoder.Convert(chars, charIndex, charsRead - charIndex,
                                    bytes, 0, UseBufferSize, flush,
                                    out charsUsed, out bytesUsed, out completed);

// The conversion produced the number of bytes indicated by bytesUsed. Write that number
// of bytes to the output file.
                    outputFile.Write(bytes, 0, bytesUsed);

// Increment charIndex to the next block of characters in the input buffer, if any, to convert.
                    charIndex += charsUsed;
                }
            }
            while(charsRead != 0);

            outputFile.Close();
            fs.Close();
            inputFile.Close();
        }

// --------------------------------------------------------------------------------------------
// Use the Decoder.Convert() method to convert a file of encoded bytes to a file of characters.
// --------------------------------------------------------------------------------------------
        static void DecoderConvert(String inputFileName, String outputFileName, Encoding enc)
        {
// Convert an input file of of encoded bytes to an output file characters.
// StreamWriter could convert the input file for us, but we'll perform the conversion 
// ourselves.

            StreamWriter outputFile = new StreamWriter(outputFileName, false, Encoding.Unicode);

// Read the input as a binary file so we can detect the Byte Order Mark.
            FileStream fs = new FileStream(inputFileName, FileMode.Open);
            BinaryReader inputFile = new BinaryReader(fs);

// Get a Decoder.
            Decoder decoder = enc.GetDecoder();
            
// Guarantee the output buffer large enough to convert a few characters.
            int UseBufferSize = 64;
            if (UseBufferSize < enc.GetMaxCharCount(10))
                    UseBufferSize = enc.GetMaxCharCount(10);
            char[] chars = new char[UseBufferSize];

// Intentionally make the input byte buffer larger than the output character buffer so the 
// conversion loop executes more than one cycle. 

            byte[] bytes = new byte[UseBufferSize * 4];
            int bytesRead;
            do
            {
// Read at most the number of bytes that will fit in the input buffer. The 
// return value is the actual number of bytes read, or zero if no bytes remain. 

                bytesRead = inputFile.Read(bytes, 0, UseBufferSize * 4);
   
                bool completed = false;
                int byteIndex = 0;
                int bytesUsed;
                int charsUsed;

                while (!completed)
                {
// If this is the last input data, flush the decoder's internal buffer and state.

                    bool flush = (bytesRead == 0);
                    decoder.Convert(bytes, byteIndex, bytesRead - byteIndex,
                                    chars, 0, UseBufferSize, flush,
                                    out bytesUsed, out charsUsed, out completed);

// The conversion produced the number of characters indicated by charsUsed. Write that number
// of characters to the output file.

                    outputFile.Write(chars, 0, charsUsed);

// Increment byteIndex to the next block of bytes in the input buffer, if any, to convert.
                    byteIndex += bytesUsed;
                }
            }
            while(bytesRead != 0);

            outputFile.Close();
            fs.Close();
            inputFile.Close();
        }        

// --------------------------------------------------------------------------------------------
// Create a large file of UTF-16 encoded Unicode characters. 
// --------------------------------------------------------------------------------------------
        static void CreateTestFile(String FileName)
        {
// StreamWriter defaults to UTF-8 encoding so explicitly specify Unicode, that is, 
// UTF-16, encoding.
            StreamWriter file = new StreamWriter(FileName, false, Encoding.Unicode);

// Write a line of text 100 times.
            for (int i = 0; i < 100; i++)
            {
                file.WriteLine("This is an example input file used by the convert example.");
            }

// Write Unicode characters from U+0000 to, but not including, the surrogate character range.
            for (char c = (char)0; c < (char)0xD800; c++)
            {
                file.Write(c);
            }
            file.Close();
        }
    }

/*
This code example produces the following results:

(Execute the -dir- console window command and examine the files created.)

Example.txt, which contains 122,594 bytes (61,297 UTF-16 encoded characters).
UTF8.txt, which contains 169,712 UTF-8 encoded bytes.
UTF16.txt, which contains 122,594 bytes (61,297 UTF-16 encoded characters).

(Execute the -comp- console window command and compare the two Unicode files.)

>comp example.txt utf16.txt /L
Comparing example.txt and utf16.txt...
Files compare OK

(The two files are equal.)

*/
' This code example demonstrates the Encoder.Convert() and Decoder.Convert methods. 
' This example uses files for input and output, but any source that can be expressed
' as a stream can be used instead.

Imports System
Imports System.Text
Imports System.IO

Public Class Sample
    Shared Sub Main(ByVal args() As String) 
        ' Create a large file of UTF-16 encoded Unicode characters. The file is named Example.txt, 
        ' and is used as input to the Encoder.Convert() method. 
        CreateTestFile("Example.txt")
        
        
        ' Using an input file of UTF-16 encoded characters named Example.txt, create an output file 
        ' of UTF-8 encoded bytes named UTF8.txt.
        EncoderConvert("Example.txt", "UTF8.txt", Encoding.UTF8)
        
        ' Using an input file of UTF-8 encoded bytes named UTF8.txt, create an output file 
        ' of UTF-16 encoded characters named UTF16.txt.
        DecoderConvert("UTF8.txt", "UTF16.txt", Encoding.UTF8)
    
    End Sub 'Main
    
    ' --------------------------------------------------------------------------------------------
    ' Use the Encoder.Convert() method to convert a file of characters to a file of encoded bytes.
    ' --------------------------------------------------------------------------------------------
    Shared Sub EncoderConvert(ByVal inputFileName As String, ByVal outputFileName As String, ByVal enc As Encoding) 
        ' Convert an input file of characters to an output file of encoded bytes.
        ' StreamWriter could convert the input file for us, but we'll perform the conversion 
        ' ourselves.
        Dim fs As New FileStream(outputFileName, FileMode.Create)
        Dim outputFile As New BinaryWriter(fs)
        
        ' StreamReader will detect Unicode encoding from the Byte Order Mark that heads the input file.
        Dim inputFile As New StreamReader(inputFileName)
        
        ' Get an Encoder.
        Dim encoder As Encoder = enc.GetEncoder()
        
        ' Guarantee the output buffer large enough to convert a few characters.
        Dim UseBufferSize As Integer = 64
        If UseBufferSize < enc.GetMaxByteCount(10) Then
            UseBufferSize = enc.GetMaxByteCount(10)
        End If
        Dim bytes(UseBufferSize) As Byte
        
        ' Intentionally make the input character buffer larger than the output byte buffer so the 
        ' conversion loop executes more than one cycle. 
        Dim chars(UseBufferSize * 4) As Char
        Dim charsRead As Integer
        Do
            ' Read at most the number of characters that will fit in the input buffer. The return 
            ' value is the actual number of characters read, or zero if no characters remain. 
            charsRead = inputFile.Read(chars, 0, UseBufferSize * 4)
            
            Dim completed As Boolean = False
            Dim charIndex As Integer = 0
            Dim charsUsed As Integer
            Dim bytesUsed As Integer
            
            While Not completed
                ' If this is the last input data, flush the encoder's internal buffer and state.
                Dim flush As Boolean = charsRead = 0
                encoder.Convert(chars, charIndex, charsRead - charIndex, bytes, 0, UseBufferSize, flush, charsUsed, bytesUsed, completed)
                
                ' The conversion produced the number of bytes indicated by bytesUsed. Write that number
                ' of bytes to the output file.
                outputFile.Write(bytes, 0, bytesUsed)
                
                ' Increment charIndex to the next block of characters in the input buffer, if any, to convert.
                charIndex += charsUsed
            End While
        Loop While charsRead <> 0
        
        outputFile.Close()
        fs.Close()
        inputFile.Close()
    
    End Sub 'EncoderConvert
    
    ' --------------------------------------------------------------------------------------------
    ' Use the Decoder.Convert() method to convert a file of encoded bytes to a file of characters.
    ' --------------------------------------------------------------------------------------------
    Shared Sub DecoderConvert(ByVal inputFileName As String, ByVal outputFileName As String, ByVal enc As Encoding) 
        ' Convert an input file of of encoded bytes to an output file characters.
        ' StreamWriter could convert the input file for us, but we'll perform the conversion 
        ' ourselves.
        Dim outputFile As New StreamWriter(outputFileName, False, Encoding.Unicode)
        
        ' Read the input as a binary file so we can detect the Byte Order Mark.
        Dim fs As New FileStream(inputFileName, FileMode.Open)
        Dim inputFile As New BinaryReader(fs)
        
        ' Get a Decoder.
        Dim decoder As Decoder = enc.GetDecoder()
        
        ' Guarantee the output buffer large enough to convert a few characters.
        Dim UseBufferSize As Integer = 64
        If UseBufferSize < enc.GetMaxCharCount(10) Then
            UseBufferSize = enc.GetMaxCharCount(10)
        End If
        Dim chars(UseBufferSize) As Char
        
        ' Intentionally make the input byte buffer larger than the output character buffer so the 
        ' conversion loop executes more than one cycle. 
        Dim bytes(UseBufferSize * 4) As Byte
        Dim bytesRead As Integer
        Do
            ' Read at most the number of bytes that will fit in the input buffer. The 
            ' return value is the actual number of bytes read, or zero if no bytes remain. 
            bytesRead = inputFile.Read(bytes, 0, UseBufferSize * 4)
            
            Dim completed As Boolean = False
            Dim byteIndex As Integer = 0
            Dim bytesUsed As Integer
            Dim charsUsed As Integer
            
            While Not completed
                ' If this is the last input data, flush the decoder's internal buffer and state.
                Dim flush As Boolean = bytesRead = 0
                decoder.Convert(bytes, byteIndex, bytesRead - byteIndex, chars, 0, UseBufferSize, flush, bytesUsed, charsUsed, completed)
                
                ' The conversion produced the number of characters indicated by charsUsed. Write that number
                ' of characters to the output file.
                outputFile.Write(chars, 0, charsUsed)
                
                ' Increment byteIndex to the next block of bytes in the input buffer, if any, to convert.
                byteIndex += bytesUsed
            End While
        Loop While bytesRead <> 0
        
        outputFile.Close()
        fs.Close()
        inputFile.Close()
    
    End Sub 'DecoderConvert
    
    ' --------------------------------------------------------------------------------------------
    ' Create a large file of UTF-16 encoded Unicode characters. 
    ' --------------------------------------------------------------------------------------------
    Shared Sub CreateTestFile(ByVal FileName As String) 
        ' StreamWriter defaults to UTF-8 encoding so explicitly specify Unicode, that is, 
        ' UTF-16, encoding.
        Dim file As New StreamWriter(FileName, False, Encoding.Unicode)
        
        ' Write a line of text 100 times.
        Dim i As Integer
        For i = 0 To 99
            file.WriteLine("This is an example input file used by the convert example.")
        Next i
        
        ' Write Unicode characters from U+0000 to, but not including, the surrogate character range.
        Dim c As Integer
        For c = 0 To &HD800
            file.Write(ChrW(c))
        Next c
        file.Close()
    
    End Sub 'CreateTestFile
End Class 'Sample

'
'This code example produces the following results:
'
'(Execute the -dir- console window command and examine the files created.)
'
'Example.txt, which contains 122,594 bytes (61,297 UTF-16 encoded characters).
'UTF8.txt, which contains 169,712 UTF-8 encoded bytes.
'UTF16.txt, which contains 122,594 bytes (61,297 UTF-16 encoded characters).
'
'(Execute the -comp- console window command and compare the two Unicode files.)
'
'>comp example.txt utf16.txt /L
'Comparing example.txt and utf16.txt...
'Files compare OK
'
'(The two files are equal.)
'

Comentarios

Recuerde que el Decoder objeto guarda el estado entre las llamadas a Convert.Remember that the Decoder object saves state between calls to Convert. Cuando la aplicación se realiza con un flujo de datos, se debe establecer el flush parámetro true para asegurarse de que se vacíe la información de estado.When the application is done with a stream of data, it should set the flush parameter to true to make sure that the state information is flushed. Con esta configuración, el descodificador pasa por alto los bytes no válidos al final del bloque de datos y borra el búfer interno.With this setting, the decoder ignores invalid bytes at the end of the data block and clears the internal buffer. Los datos procesados restantes que forma parte de una unidad lógica, como suplente alto de un par suplente, se convierten según la configuración de reserva actual.Any remaining processed data that is part of a logical unit, such as the high surrogate of a surrogate pair, is converted according to the current fallback settings.

El Convert método está diseñado para usarse en un bucle para descodificar una cantidad arbitraria de entrada, como los datos leídos de un archivo o secuencia.The Convert method is designed to be used in a loop to decode an arbitrary amount of input, such as data read from a file or stream. Almacena el resultado de la operación de descodificación en un búfer de tamaño fijo.It stores the output of the decoding operation in a fixed-size buffer. GetChars se iniciará una excepción si el búfer de salida no es suficientemente grande, pero Convert se rellenará tanto espacio como sea posible y devolverá los bytes leídos y caracteres escritos.GetChars will throw an exception if the output buffer isn't large enough, but Convert will fill as much space as possible and return the bytes read and chars written. Consulte también el Encoding.GetChars tema para obtener más comentarios.Also see the Encoding.GetChars topic for more comments.

El completed parámetro de salida que indica si todos los datos en el búfer de entrada se convierten y se almacena en el búfer de salida.The completed output parameter indicates whether all the data in the input buffer was converted and stored in the output buffer. Este parámetro se establece en false si el número de bytes especificado por el byteCount parámetro no se puede convertir sin exceder el número de caracteres especificados por el charCount parámetro.This parameter is set to false if the number of bytes specified by the byteCount parameter cannot be converted without exceeding the number of characters specified by the charCount parameter. En esa situación, la aplicación debe usar el contenido del búfer de salida o proporcione un nuevo búfer de salida, incremento el bytes parámetro por el número de bytes especificado por el bytesUsed parámetro, a continuación, llame a la Convert método nuevo para procesar las entradas restantes.In that situation, the application should use the contents of the output buffer or provide a new output buffer, increment the bytes parameter by the number of bytes specified by the bytesUsed parameter, then call the Convert method again to process the remaining input.

El completed parámetro también se puede establecer en false, aunque el bytesUsed y byteCount parámetros son iguales.The completed parameter can also be set to false, even though the bytesUsed and byteCount parameters are equal. Esta situación se produce si todavía hay datos en el Decoder objeto que no se ha almacenado en el bytes búfer.This situation occurs if there is still data in the Decoder object that has not been stored in the bytes buffer.

Se aplica a