Partilhar via


Encoding.BigEndianUnicode Propriedade

Definição

Obtém uma codificação para o formato UTF-16 que usa a ordem de byte big endian.

public:
 static property System::Text::Encoding ^ BigEndianUnicode { System::Text::Encoding ^ get(); };
public static System.Text.Encoding BigEndianUnicode { get; }
member this.BigEndianUnicode : System.Text.Encoding
Public Shared ReadOnly Property BigEndianUnicode As Encoding

Valor da propriedade

Encoding

Um objeto de codificação para o formato UTF-16 que usa a ordem de byte big endian.

Exemplos

O exemplo a seguir lê um arquivo de texto com uma codificação UTF-16 usando a ordem de byte big endian.

using namespace System;
using namespace System::IO;
int main()
{
   
   // Read a text file saved with Big Endian Unicode encoding.
   System::Text::Encoding^ encoding = System::Text::Encoding::BigEndianUnicode;
   StreamReader^ reader = gcnew StreamReader( "TextFile.txt",encoding );
   String^ line = reader->ReadLine();
   while ( line != nullptr )
   {
      Console::WriteLine( line );
      line = reader->ReadLine();
   }
}
using System;
using System.IO;

namespace BigEndianExample
{
   public class Class1 
   {
      public static void Main(string[] args) 
      {
         // Read a text file saved with Big Endian Unicode encoding.
         System.Text.Encoding encoding = System.Text.Encoding.BigEndianUnicode;
         StreamReader reader = new StreamReader("TextFile.txt", encoding);
         string line = reader.ReadLine();
         while (line != null) 
         {
            Console.WriteLine(line);
            line = reader.ReadLine();
         }
       }
    }
}
Imports System.IO

Namespace BigEndianExample
   Public Class Class1
      Public Overloads Shared Sub Main()
         ' Read a text file saved with Big Endian Unicode encoding.
         Dim encoding As System.Text.Encoding = System.Text.Encoding.BigEndianUnicode
         Dim reader As New StreamReader("TextFile.txt", encoding)
         Dim line As String = reader.ReadLine()
         While Not (line Is Nothing)
            Console.WriteLine(line)
            line = reader.ReadLine()
         End While
      End Sub
   End Class
End Namespace

O exemplo a seguir determina o número de bytes necessários para codificar uma matriz de caracteres, codifica os caracteres e exibe os bytes resultantes.

using namespace System;
using namespace System::Text;
void PrintCountsAndBytes( array<Char>^chars, Encoding^ enc );
void PrintHexBytes( array<Byte>^bytes );
int main()
{
   
   // The characters to encode:
   //    Latin Small Letter Z (U+007A)
   //    Latin Small Letter A (U+0061)
   //    Combining Breve (U+0306)
   //    Latin Small Letter AE With Acute (U+01FD)
   //    Greek Small Letter Beta (U+03B2)
   //    a high-surrogate value (U+D8FF)
   //    a low-surrogate value (U+DCFF)
   array<Char>^myChars = gcnew array<Char>{
      L'z','a',L'\u0306',L'\u01FD',L'\u03B2',L'\xD8FF',L'\xDCFF'
   };
   
   // Get different encodings.
   Encoding^ u7 = Encoding::UTF7;
   Encoding^ u8 = Encoding::UTF8;
   Encoding^ u16LE = Encoding::Unicode;
   Encoding^ u16BE = Encoding::BigEndianUnicode;
   Encoding^ u32 = Encoding::UTF32;
   
   // Encode the entire array, and print out the counts and the resulting bytes.
   PrintCountsAndBytes( myChars, u7 );
   PrintCountsAndBytes( myChars, u8 );
   PrintCountsAndBytes( myChars, u16LE );
   PrintCountsAndBytes( myChars, u16BE );
   PrintCountsAndBytes( myChars, u32 );
}

void PrintCountsAndBytes( array<Char>^chars, Encoding^ enc )
{
   
   // Display the name of the encoding used.
   Console::Write( "{0,-30} :", enc );
   
   // Display the exact byte count.
   int iBC = enc->GetByteCount( chars );
   Console::Write( " {0,-3}", iBC );
   
   // Display the maximum byte count.
   int iMBC = enc->GetMaxByteCount( chars->Length );
   Console::Write( " {0,-3} :", iMBC );
   
   // Encode the array of chars.
   array<Byte>^bytes = enc->GetBytes( chars );
   
   // Display all the encoded bytes.
   PrintHexBytes( bytes );
}

void PrintHexBytes( array<Byte>^bytes )
{
   if ( (bytes == nullptr) || (bytes->Length == 0) )
      Console::WriteLine( "<none>" );
   else
   {
      for ( int i = 0; i < bytes->Length; i++ )
         Console::Write( "{0:X2} ", bytes[ i ] );
      Console::WriteLine();
   }
}

/* 
This code produces the following output.

System.Text.UTF7Encoding       : 18  23  :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
System.Text.UTF8Encoding       : 12  24  :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
System.Text.UnicodeEncoding    : 14  16  :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
System.Text.UnicodeEncoding    : 14  16  :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
System.Text.UTF32Encoding      : 24  32  :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00

*/
using System;
using System.Text;

public class SamplesEncoding  {

   public static void Main()  {

      // The characters to encode:
      //    Latin Small Letter Z (U+007A)
      //    Latin Small Letter A (U+0061)
      //    Combining Breve (U+0306)
      //    Latin Small Letter AE With Acute (U+01FD)
      //    Greek Small Letter Beta (U+03B2)
      //    a high-surrogate value (U+D8FF)
      //    a low-surrogate value (U+DCFF)
      char[] myChars = new char[] { 'z', 'a', '\u0306', '\u01FD', '\u03B2', '\uD8FF', '\uDCFF' };

      // Get different encodings.
      Encoding  u7    = Encoding.UTF7;
      Encoding  u8    = Encoding.UTF8;
      Encoding  u16LE = Encoding.Unicode;
      Encoding  u16BE = Encoding.BigEndianUnicode;
      Encoding  u32   = Encoding.UTF32;

      // Encode the entire array, and print out the counts and the resulting bytes.
      PrintCountsAndBytes( myChars, u7 );
      PrintCountsAndBytes( myChars, u8 );
      PrintCountsAndBytes( myChars, u16LE );
      PrintCountsAndBytes( myChars, u16BE );
      PrintCountsAndBytes( myChars, u32 );
   }

   public static void PrintCountsAndBytes( char[] chars, Encoding enc )  {

      // Display the name of the encoding used.
      Console.Write( "{0,-30} :", enc.ToString() );

      // Display the exact byte count.
      int iBC  = enc.GetByteCount( chars );
      Console.Write( " {0,-3}", iBC );

      // Display the maximum byte count.
      int iMBC = enc.GetMaxByteCount( chars.Length );
      Console.Write( " {0,-3} :", iMBC );

      // Encode the array of chars.
      byte[] bytes = enc.GetBytes( chars );

      // Display all the encoded bytes.
      PrintHexBytes( bytes );
   }

   public static void PrintHexBytes( byte[] bytes )  {

      if (( bytes == null ) || ( bytes.Length == 0 ))
        {
            Console.WriteLine( "<none>" );
        }
        else  {
         for ( int i = 0; i < bytes.Length; i++ )
            Console.Write( "{0:X2} ", bytes[i] );
         Console.WriteLine();
      }
   }
}


/* 
This code produces the following output.

System.Text.UTF7Encoding       : 18  23  :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
System.Text.UTF8Encoding       : 12  24  :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
System.Text.UnicodeEncoding    : 14  16  :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
System.Text.UnicodeEncoding    : 14  16  :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
System.Text.UTF32Encoding      : 24  32  :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00

*/
Imports System.Text

Public Class SamplesEncoding   

   Public Shared Sub Main()

      ' The characters to encode:
      '    Latin Small Letter Z (U+007A)
      '    Latin Small Letter A (U+0061)
      '    Combining Breve (U+0306)
      '    Latin Small Letter AE With Acute (U+01FD)
      '    Greek Small Letter Beta (U+03B2)
      '    a high-surrogate value (U+D8FF)
      '    a low-surrogate value (U+DCFF)
      Dim myChars() As Char = {"z"c, "a"c, ChrW(&H0306), ChrW(&H01FD), ChrW(&H03B2), ChrW(&HD8FF), ChrW(&HDCFF)}
 

      ' Get different encodings.
      Dim u7 As Encoding = Encoding.UTF7
      Dim u8 As Encoding = Encoding.UTF8
      Dim u16LE As Encoding = Encoding.Unicode
      Dim u16BE As Encoding = Encoding.BigEndianUnicode
      Dim u32 As Encoding = Encoding.UTF32

      ' Encode the entire array, and print out the counts and the resulting bytes.
      PrintCountsAndBytes(myChars, u7)
      PrintCountsAndBytes(myChars, u8)
      PrintCountsAndBytes(myChars, u16LE)
      PrintCountsAndBytes(myChars, u16BE)
      PrintCountsAndBytes(myChars, u32)

   End Sub


   Public Shared Sub PrintCountsAndBytes(chars() As Char, enc As Encoding)

      ' Display the name of the encoding used.
      Console.Write("{0,-30} :", enc.ToString())

      ' Display the exact byte count.
      Dim iBC As Integer = enc.GetByteCount(chars)
      Console.Write(" {0,-3}", iBC)

      ' Display the maximum byte count.
      Dim iMBC As Integer = enc.GetMaxByteCount(chars.Length)
      Console.Write(" {0,-3} :", iMBC)

      ' Encode the array of chars.
      Dim bytes As Byte() = enc.GetBytes(chars)

      ' Display all the encoded bytes.
      PrintHexBytes(bytes)

   End Sub


   Public Shared Sub PrintHexBytes(bytes() As Byte)

      If bytes Is Nothing OrElse bytes.Length = 0 Then
         Console.WriteLine("<none>")
      Else
         Dim i As Integer
         For i = 0 To bytes.Length - 1
            Console.Write("{0:X2} ", bytes(i))
         Next i
         Console.WriteLine()
      End If

   End Sub

End Class


'This code produces the following output.
'
'System.Text.UTF7Encoding       : 18  23  :7A 61 2B 41 77 59 42 2F 51 4F 79 32 50 2F 63 2F 77 2D
'System.Text.UTF8Encoding       : 12  24  :7A 61 CC 86 C7 BD CE B2 F1 8F B3 BF
'System.Text.UnicodeEncoding    : 14  16  :7A 00 61 00 06 03 FD 01 B2 03 FF D8 FF DC
'System.Text.UnicodeEncoding    : 14  16  :00 7A 00 61 03 06 01 FD 03 B2 D8 FF DC FF
'System.Text.UTF32Encoding      : 24  32  :7A 00 00 00 61 00 00 00 06 03 00 00 FD 01 00 00 B2 03 00 00 FF FC 04 00

Comentários

O UnicodeEncoding objeto retornado por essa propriedade pode não ter o comportamento apropriado para seu aplicativo. Ele usa o fallback de substituição para substituir cada cadeia de caracteres que não pode ser codificada e cada byte que não pode decodificar com um caractere de ponto de interrogação ("?"). Em vez disso, você pode chamar o UnicodeEncoding.UnicodeEncoding(Boolean, Boolean, Boolean) construtor para instanciar um UnicodeEncoding objeto big endian cujo fallback seja um EncoderFallbackException ou um DecoderFallbackException , como ilustra o exemplo a seguir.

using System;
using System.Text;

public class Example
{
   public static void Main()
   {
      byte[] bytes = { 0x00, 0x20, 0xd8, 0x01, 0x00, 0x68, 0xA7, 0x00 };
      Encoding enc = new UnicodeEncoding(true, true, true);
      
      try {
         string value = enc.GetString(bytes);
         Console.WriteLine();
         Console.WriteLine("'{0}'", value);
      }
      catch (DecoderFallbackException e) {      
         Console.WriteLine("Unable to decode {0} at index {1}", 
                           ShowBytes(e.BytesUnknown), e.Index);
      }
   }

   private static string ShowBytes(byte[] bytes) 
   {
      string returnString = null;
      foreach (var byteValue in bytes)
         returnString += String.Format("0x{0:X2} ", byteValue);

      return returnString.Trim();
   }
}
// The example displays the following output:
//        Unable to decode 0xD8 0x01 at index 4
Imports System.Text

Module Example
   Public Sub Main()
      Dim bytes() As Byte = { &h00, &h20, &hd8, &h01, &h00, &h68, &hA7, &h00}
      Dim enc As Encoding = New UnicodeEncoding(True, True, True)
      
      Try
         Dim value As String = enc.GetString(bytes)
         Console.WriteLine()
         Console.WriteLine("'{0}'", value)
      Catch e As DecoderFallbackException      
         Console.WriteLine("Unable to decode {0} at index {1}", 
                           ShowBytes(e.BytesUnknown), e.Index)
      End Try
   End Sub
   
   Private Function ShowBytes(bytes As Byte()) As String
      Dim returnString As String = Nothing
      For Each byteValue In bytes
         returnString += String.Format("0x{0:X2} ", byteValue)
      Next
      Return returnString.Trim()
   End Function
End Module
' The example displays the following output:
'       Unable to decode 0xD8 0x01 at index 4

O UnicodeEncoding objeto retornado tem BodyName HeaderName Propriedades, e WebName , que geram o nome "unicodeFFFE". Embora a marca de ordem de byte UTF-16 big endian seja hexadecimal FEFF, o nome "unicodeFFFE" foi escolhido porque a marca de ordem de byte aparece como FFFE hexadecimal em little endian computadores Windows.

Aplica-se a

Confira também