Encoding.GetEncoding 方法

参考

定义

命名空间:: System.Text

程序集:: System.Text.Encoding.dll

程序集:: System.Runtime.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

返回指定代码页的编码。

重载

GetEncoding(Int32)	返回与指定代码页标识符关联的编码。
GetEncoding(String)	返回与指定代码页名称关联的编码。
GetEncoding(Int32, EncoderFallback, DecoderFallback)	返回与指定代码页标识符关联的编码。参数指定一个错误处理程序，用于处理无法编码的字符和无法解码的字节序列。
GetEncoding(String, EncoderFallback, DecoderFallback)	返回与指定代码页名称关联的编码。参数指定一个错误处理程序，用于处理无法编码的字符和无法解码的字节序列。

GetEncoding(Int32)

Source:: Encoding.cs

Source:: Encoding.cs

Source:: Encoding.cs

返回与指定代码页标识符关联的编码。

public:
 static System::Text::Encoding ^ GetEncoding(int codepage);

public static System.Text.Encoding GetEncoding (int codepage);

static member GetEncoding : int -> System.Text.Encoding

Public Shared Function GetEncoding (codepage As Integer) As Encoding

参数

codepage: Int32

首选编码的代码页标识符。有关可能值的列表，请参见 Encoding。

或

0（零），使用默认编码。

Encoding

与指定代码页关联的编码。

例外

ArgumentOutOfRangeException

codepage 小于零或大于 65535。

ArgumentException

基础平台不支持 codepage。

NotSupportedException

基础平台不支持 codepage。

示例

下面的示例获取相同编码的两个实例（一个按代码页，另一个按名称），并检查它们是否相等。

using namespace System;
using namespace System::Text;
int main()
{
   
   // Get a UTF-32 encoding by codepage.
   Encoding^ e1 = Encoding::GetEncoding( 12000 );
   
   // Get a UTF-32 encoding by name.
   Encoding^ e2 = Encoding::GetEncoding( "utf-32" );
   
   // Check their equality.
   Console::WriteLine( "e1 equals e2? {0}", e1->Equals( e2 ) );
}

/* 
This code produces the following output.

e1 equals e2? True

*/

using System;
using System.Text;

public class SamplesEncoding  {

   public static void Main()  {

      // Get a UTF-32 encoding by codepage.
      Encoding e1 = Encoding.GetEncoding( 12000 );

      // Get a UTF-32 encoding by name.
      Encoding e2 = Encoding.GetEncoding( "utf-32" );

      // Check their equality.
      Console.WriteLine( "e1 equals e2? {0}", e1.Equals( e2 ) );
   }
}


/* 
This code produces the following output.

e1 equals e2? True

*/

Imports System.Text

Public Class SamplesEncoding   

   Public Shared Sub Main()

      ' Get a UTF-32 encoding by codepage.
      Dim e1 As Encoding = Encoding.GetEncoding(12000)

      ' Get a UTF-32 encoding by name.
      Dim e2 As Encoding = Encoding.GetEncoding("utf-32")

      ' Check their equality.
      Console.WriteLine("e1 equals e2? {0}", e1.Equals(e2))

   End Sub

End Class


'This code produces the following output.
'
'e1 equals e2? True

注解

回退处理程序依赖于的编码类型 codepage 。如果 codepage 是代码页或双字节字符集（DBCS）编码，则使用最佳回退处理程序。否则，将使用替代回退处理程序。这些回退处理程序可能不适合您的应用程序。若要指定由指定的编码使用的回退处理程序 codepage ，可以调用 GetEncoding(Int32, EncoderFallback, DecoderFallback) 重载。

在 .NET Framework 中， GetEncoding 方法依赖于基础平台来支持大多数代码页。但是，.NET Framework 本机支持某些编码。有关代码页的列表，请参阅编码列表。在 .NET Core 中， GetEncoding 方法返回 .Net core 本机支持的编码。在这两种 .NET 实现上，都可以调用 GetEncodings 方法来获取 EncodingInfo 对象的数组，这些对象包含有关所有可用的编码的信息。

除了本机在 .NET Core 上可用或在 .NET Framework 的特定平台版本上受支持的编码以外，该 GetEncoding 方法还返回通过注册对象提供的任何其他编码 EncodingProvider 。如果多个对象已注册了相同的编码 EncodingProvider ，则此方法将返回最后一个注册的。

还可以为参数提供0值 codepage 。其确切行为取决于是否已通过注册对象提供了任何编码 EncodingProvider ：

如果注册了一个或多个编码提供程序，则它会返回上次注册的提供程序的编码，该提供程序已选择在向 GetEncoding 方法传递 codepage 参数0时返回编码。
在 .NET Framework 上，如果没有注册任何编码提供程序，如果 CodePagesEncodingProvider 是注册的编码提供程序，或者如果没有已注册的编码提供程序处理 codepage 值0，则返回操作系统的活动代码页。若要确定 Windows 系统上的活动代码页，请从 .NET Framework调用 Windows GetACP 函数。
在 .NET Core 中，如果未注册任何编码提供程序，或者没有任何注册的编码提供程序处理 codepage 值0，则返回 UTF8Encoding 。

注意

某些不受支持的代码页会 ArgumentException 引发，而另一些则 NotSupportedException 导致。因此，您的代码必须捕获 "异常" 部分中指示的所有异常。
在 .NET 5 及更高版本中，不支持表示 UTF-7 的代码页标识符 65000。

注意

ANSI 代码页在不同计算机上可能不同，并且可以在一台计算机上更改，导致数据损坏。出于此原因，如果活动代码页是 ANSI 代码页，则不建议使用返回的默认代码页对数据进行编码和解码 Encoding.GetEncoding(0) 。为获得最一致的结果，应使用 Unicode 编码，例如 UTF-8 （代码页65001）或 UTF-16，而不是使用特定的代码页。

GetEncoding使用默认设置返回缓存的实例。应使用派生类的构造函数获取具有不同设置的实例。例如， UTF32Encoding 类提供可让你启用错误检测的构造函数。

另请参阅

适用于

GetEncoding(String)

Source:: Encoding.cs

Source:: Encoding.cs

Source:: Encoding.cs

返回与指定代码页名称关联的编码。

public:
 static System::Text::Encoding ^ GetEncoding(System::String ^ name);

public static System.Text.Encoding GetEncoding (string name);

static member GetEncoding : string -> System.Text.Encoding

Public Shared Function GetEncoding (name As String) As Encoding

参数

name: String

首选编码的代码页名称。 WebName 属性返回的所有值均有效。有关可能值的列表，请参见 Encoding。

Encoding

与指定的代码页关联的编码。

例外

ArgumentException

name 不是有效的代码页名称。

或

基础平台不支持 name 所指示的代码页。

示例

下面的示例获取相同编码的两个实例（一个按代码页，另一个按名称），并检查它们是否相等。

using namespace System;
using namespace System::Text;
int main()
{
   
   // Get a UTF-32 encoding by codepage.
   Encoding^ e1 = Encoding::GetEncoding( 12000 );
   
   // Get a UTF-32 encoding by name.
   Encoding^ e2 = Encoding::GetEncoding( "utf-32" );
   
   // Check their equality.
   Console::WriteLine( "e1 equals e2? {0}", e1->Equals( e2 ) );
}

/* 
This code produces the following output.

e1 equals e2? True

*/

using System;
using System.Text;

public class SamplesEncoding  {

   public static void Main()  {

      // Get a UTF-32 encoding by codepage.
      Encoding e1 = Encoding.GetEncoding( 12000 );

      // Get a UTF-32 encoding by name.
      Encoding e2 = Encoding.GetEncoding( "utf-32" );

      // Check their equality.
      Console.WriteLine( "e1 equals e2? {0}", e1.Equals( e2 ) );
   }
}


/* 
This code produces the following output.

e1 equals e2? True

*/

Imports System.Text

Public Class SamplesEncoding   

   Public Shared Sub Main()

      ' Get a UTF-32 encoding by codepage.
      Dim e1 As Encoding = Encoding.GetEncoding(12000)

      ' Get a UTF-32 encoding by name.
      Dim e2 As Encoding = Encoding.GetEncoding("utf-32")

      ' Check their equality.
      Console.WriteLine("e1 equals e2? {0}", e1.Equals(e2))

   End Sub

End Class


'This code produces the following output.
'
'e1 equals e2? True

注解

回退处理程序依赖于的编码类型 name 。如果 name 是代码页或双字节字符集（DBCS）编码，则使用最佳回退处理程序。否则，将使用替代回退处理程序。这些回退处理程序可能不适合您的应用程序。若要指定由指定的编码使用的回退处理程序 name ，可以调用 GetEncoding(String, EncoderFallback, DecoderFallback) 重载。

在 .NET 5 及更高版本中，不支持代码页名称 utf-7 。

注意

在不同的计算机上，ANSI 代码页可能会不同，或者可以针对一台计算机进行更改，从而导致数据损坏。为获得最一致的结果，请使用 Unicode，如 UTF-8 （代码页65001）或 UTF-16，而不是特定的代码页。

GetEncoding使用默认设置返回缓存的实例。应使用派生类的构造函数获取具有不同设置的实例。例如， UTF32Encoding 类提供可让你启用错误检测的构造函数。

另请参阅

适用于

GetEncoding(Int32, EncoderFallback, DecoderFallback)

Source:: Encoding.cs

Source:: Encoding.cs

Source:: Encoding.cs

返回与指定代码页标识符关联的编码。参数指定一个错误处理程序，用于处理无法编码的字符和无法解码的字节序列。

public:
 static System::Text::Encoding ^ GetEncoding(int codepage, System::Text::EncoderFallback ^ encoderFallback, System::Text::DecoderFallback ^ decoderFallback);

public static System.Text.Encoding GetEncoding (int codepage, System.Text.EncoderFallback encoderFallback, System.Text.DecoderFallback decoderFallback);

static member GetEncoding : int * System.Text.EncoderFallback * System.Text.DecoderFallback -> System.Text.Encoding

Public Shared Function GetEncoding (codepage As Integer, encoderFallback As EncoderFallback, decoderFallback As DecoderFallback) As Encoding

参数

codepage: Int32

首选编码的代码页标识符。有关可能值的列表，请参见 Encoding。

或

0（零），使用默认编码。

encoderFallback: EncoderFallback

一个对象，在无法用当前编码对字符进行编码时，该对象可用来提供错误处理过程。

decoderFallback: DecoderFallback

一个对象，在无法用当前编码对字节序列进行解码时，该对象可用来提供错误处理过程。

Encoding

与指定代码页关联的编码。

例外

ArgumentOutOfRangeException

codepage 小于零或大于 65535。

ArgumentException

基础平台不支持 codepage。

NotSupportedException

基础平台不支持 codepage。

示例

下面的示例演示 Encoding.GetEncoding(String, EncoderFallback, DecoderFallback) 方法。

// This example demonstrates the EncoderReplacementFallback class.

using namespace System;
using namespace System::Text;

int main()
{
    // Create an encoding, which is equivalent to calling the
    // ASCIIEncoding class constructor.
    // The EncoderReplacementFallback parameter specifies that the
    // string, "(unknown)", replace characters that cannot be encoded.
    // A decoder replacement fallback is also specified, but in this
    // code example the decoding operation cannot fail.

    Encoding^ ascii = Encoding::GetEncoding("us-ascii",
        gcnew EncoderReplacementFallback("(unknown)"),
        gcnew DecoderReplacementFallback("(error)"));

    // The input string consists of the Unicode characters LEFT POINTING
    // DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT
    // POINTING DOUBLE ANGLE QUOTATION MARK (U+00BB).
    // The encoding can only encode characters in the US-ASCII range of
    // U+0000 through U+007F. Consequently, the characters bracketing the
    // 'X' character are replaced with the fallback replacement string,
    // "(unknown)".

    String^ inputString = "\u00abX\u00bb";
    String^ decodedString;
    String^ twoNewLines = Environment::NewLine + Environment::NewLine;
    array <Byte>^ encodedBytes = 
        gcnew array<Byte>(ascii->GetByteCount(inputString));
    int numberOfEncodedBytes = 0;

    // ---------------------------------------------------------------------
        // Display the name of the encoding.
    Console::WriteLine("The name of the encoding is \"{0}\".{1}", 
        ascii->WebName, Environment::NewLine);

    // Display the input string in text.
    Console::WriteLine("Input string ({0} characters): \"{1}\"",
        inputString->Length, inputString);

    // Display the input string in hexadecimal.
    Console::Write("Input string in hexadecimal: ");
    for each (char c in inputString)
    {
        Console::Write("0x{0:X2} ", c);
    }
    Console::Write(twoNewLines);

    // ---------------------------------------------------------------------
    // Encode the input string.

    Console::WriteLine("Encode the input string...");
    numberOfEncodedBytes = ascii->GetBytes(inputString, 0, inputString->Length,
        encodedBytes, 0);

    // Display the encoded bytes.
    Console::WriteLine("Encoded bytes in hexadecimal ({0} bytes):{1}",
        numberOfEncodedBytes, Environment::NewLine);
    for(int i = 0; i < encodedBytes->Length; i++)
    {
        Console::Write("0x{0:X2} ", encodedBytes[i]);
        if(((i + 1) % 6) == 0)
        {
            Console::WriteLine();
        }
    }
    Console::Write(twoNewLines);

    // ---------------------------------------------------------------------
    // Decode the encoded bytes, yielding a reconstituted string.

    Console::WriteLine("Decode the encoded bytes...");
    decodedString = ascii->GetString(encodedBytes);

    // Display the input string and the decoded string for comparison.
    Console::WriteLine("Input string:  \"{0}\"", inputString);
    Console::WriteLine("Decoded string:\"{0}\"", decodedString);
}



/*
This code example produces the following results:

The name of the encoding is "us-ascii".

Input string (3 characters): "X"
Input string in hexadecimal: 0xAB 0x58 0xBB

Encode the input string...
Encoded bytes in hexadecimal (19 bytes):

0x28 0x75 0x6E 0x6B 0x6E 0x6F
0x77 0x6E 0x29 0x58 0x28 0x75
0x6E 0x6B 0x6E 0x6F 0x77 0x6E
0x29

Decode the encoded bytes...
Input string:  "X"
Decoded string:"(unknown)X(unknown)"

*/

// This example demonstrates the EncoderReplacementFallback class.

using System;
using System.Text;

class Sample
{
    public static void Main()
    {

// Create an encoding, which is equivalent to calling the
// ASCIIEncoding class constructor.
// The EncoderReplacementFallback parameter specifies that the
// string, "(unknown)", replace characters that cannot be encoded.
// A decoder replacement fallback is also specified, but in this
// code example the decoding operation cannot fail.

    Encoding ae = Encoding.GetEncoding(
                  "us-ascii",
                  new EncoderReplacementFallback("(unknown)"),
                  new DecoderReplacementFallback("(error)"));

// The input string consists of the Unicode characters LEFT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00BB).
// The encoding can only encode characters in the US-ASCII range of U+0000
// through U+007F. Consequently, the characters bracketing the 'X' character
// are replaced with the fallback replacement string, "(unknown)".

    string inputString = "\u00abX\u00bb";
    string decodedString;
    string twoNewLines = "\n\n";
    byte[] encodedBytes = new byte[ae.GetByteCount(inputString)];
    int numberOfEncodedBytes = 0;
    int ix = 0;

// --------------------------------------------------------------------------
// Display the name of the encoding.
    Console.WriteLine("The name of the encoding is \"{0}\".\n", ae.WebName);

// Display the input string in text.
    Console.WriteLine("Input string ({0} characters): \"{1}\"",
                       inputString.Length, inputString);

// Display the input string in hexadecimal.
    Console.Write("Input string in hexadecimal: ");
    foreach (char c in inputString.ToCharArray())
        {
        Console.Write("0x{0:X2} ", (int)c);
        }
    Console.Write(twoNewLines);

// --------------------------------------------------------------------------
// Encode the input string.

    Console.WriteLine("Encode the input string...");
    numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length,
                                       encodedBytes, 0);

// Display the encoded bytes.
    Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):\n",
                       numberOfEncodedBytes);
    ix = 0;
    foreach (byte b in encodedBytes)
        {
        Console.Write("0x{0:X2} ", (int)b);
        ix++;
        if (0 == ix % 6) Console.WriteLine();
        }
    Console.Write(twoNewLines);

// --------------------------------------------------------------------------
// Decode the encoded bytes, yielding a reconstituted string.

    Console.WriteLine("Decode the encoded bytes...");
    decodedString = ae.GetString(encodedBytes);

// Display the input string and the decoded string for comparison.
    Console.WriteLine("Input string:  \"{0}\"", inputString);
    Console.WriteLine("Decoded string:\"{0}\"", decodedString);
    }
}
/*
This code example produces the following results:

The name of the encoding is "us-ascii".

Input string (3 characters): "«X»"
Input string in hexadecimal: 0xAB 0x58 0xBB

Encode the input string...
Encoded bytes in hexadecimal (19 bytes):

0x28 0x75 0x6E 0x6B 0x6E 0x6F
0x77 0x6E 0x29 0x58 0x28 0x75
0x6E 0x6B 0x6E 0x6F 0x77 0x6E
0x29

Decode the encoded bytes...
Input string:  "«X»"
Decoded string:"(unknown)X(unknown)"

*/

' This example demonstrates the EncoderReplacementFallback class.
Imports System.Text

Class Sample
    Public Shared Sub Main() 
        
        ' Create an encoding, which is equivalent to calling the 
        ' ASCIIEncoding class constructor. 
        ' The EncoderReplacementFallback parameter specifies that the 
        ' string, "(unknown)", replace characters that cannot be encoded. 
        ' A decoder replacement fallback is also specified, but in this 
        ' code example the decoding operation cannot fail.  

        Dim erf As New EncoderReplacementFallback("(unknown)")
        Dim drf As New DecoderReplacementFallback("(error)")
        Dim ae As Encoding = Encoding.GetEncoding("us-ascii", erf, drf)
        
        ' The input string consists of the Unicode characters LEFT POINTING 
        ' DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING 
        ' DOUBLE ANGLE QUOTATION MARK (U+00BB). 
        ' The encoding can only encode characters in the US-ASCII range of U+0000 
        ' through U+007F. Consequently, the characters bracketing the 'X' character
        ' are replaced with the fallback replacement string, "(unknown)".

        Dim inputString As String = "«X»"
        Dim decodedString As String
        Dim twoNewLines As String = vbCrLf & vbCrLf
        Dim ix As Integer = 0
        Dim numberOfEncodedBytes As Integer = ae.GetByteCount(inputString)
        ' Counteract the compiler adding an extra byte to the array.
        Dim encodedBytes(numberOfEncodedBytes - 1) As Byte
        
        ' --------------------------------------------------------------------------
        ' Display the name of the encoding.
        Console.WriteLine("The name of the encoding is ""{0}""." & vbCrLf, ae.WebName)
        
        ' Display the input string in text.
        Console.WriteLine("Input string ({0} characters): ""{1}""", _
                           inputString.Length, inputString)
        
        ' Display the input string in hexadecimal. 
        ' Each element is converted to an integer with Convert.ToInt32.
        Console.Write("Input string in hexadecimal: ")
        Dim c As Char
        For Each c In inputString.ToCharArray()
            Console.Write("0x{0:X2} ", Convert.ToInt32(c))
        Next c
        Console.Write(twoNewLines)
        
        ' --------------------------------------------------------------------------
        ' Encode the input string. 
        Console.WriteLine("Encode the input string...")
        numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length, _
                                           encodedBytes, 0)
        
        ' Display the encoded bytes. 
        ' Each element is converted to an integer with Convert.ToInt32.
        Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):" & vbCrLf, _
                           numberOfEncodedBytes)
        ix = 0
        Dim b As Byte
        For Each b In encodedBytes
            Console.Write("0x{0:X2} ", Convert.ToInt32(b))
            ix += 1
            If 0 = ix Mod 6 Then
                Console.WriteLine()
            End If
        Next b
        Console.Write(twoNewLines)
        
        ' --------------------------------------------------------------------------
        ' Decode the encoded bytes, yielding a reconstituted string.
        Console.WriteLine("Decode the encoded bytes...")
        decodedString = ae.GetString(encodedBytes)
        
        ' Display the input string and the decoded string for comparison.
        Console.WriteLine("Input string:  ""{0}""", inputString)
        Console.WriteLine("Decoded string:""{0}""", decodedString)
    
    End Sub
End Class
'
'This code example produces the following results:
'
'The name of the encoding is "us-ascii".
'
'Input string (3 characters): "X"
'Input string in hexadecimal: 0xAB 0x58 0xBB
'
'Encode the input string...
'Encoded bytes in hexadecimal (19 bytes):
'
'0x28 0x75 0x6E 0x6B 0x6E 0x6F
'0x77 0x6E 0x29 0x58 0x28 0x75
'0x6E 0x6B 0x6E 0x6F 0x77 0x6E
'0x29
'
'Decode the encoded bytes...
'Input string:  "X"
'Decoded string:"(unknown)X(unknown)"
'

注解

注意

某些不受支持的代码页会 ArgumentException 引发异常，而其他代码页则导致引发异常 NotSupportedException 。因此，您的代码必须捕获 "异常" 部分中指示的所有异常。
在 .NET 5 及更高版本中，不支持表示 UTF-7 的代码页标识符 65000。

还可以为参数提供0值 codepage 。其确切行为取决于是否已通过注册对象提供了任何编码 EncodingProvider ：

如果注册了一个或多个编码提供程序，则它会返回上次注册的提供程序的编码，该提供程序已选择在向 GetEncoding 方法传递 codepage 参数0时返回编码。
在 .NET Framework 上，如果没有注册任何编码提供程序，如果 CodePagesEncodingProvider 是注册的编码提供程序，或者如果没有已注册的编码提供程序处理 codepage 值0，则返回活动代码页。
在 .NET Core 中，如果未注册任何编码提供程序，或者没有任何注册的编码提供程序处理 codepage 值0，则返回 UTF8Encoding 编码。

注意

ANSI 代码页在不同计算机上可能不同，并且可以在一台计算机上更改，导致数据损坏。出于此原因，如果活动代码页是 ANSI 代码页，则不建议使用返回的默认代码页对数据进行编码和解码 Encoding.GetEncoding(0) 。为获得最一致的结果，应使用 Unicode，如 UTF-8 （代码页65001）或 UTF-16，而不是特定的代码页。

若要获取与活动代码页关联的编码，可以为参数提供值 0codepage，或者如果代码在.NET Framework上运行，则检索属性的值Encoding.Default。若要确定当前活动代码页，请从 .NET Framework 调用 Windows GetACP 函数。

GetEncoding使用默认设置返回缓存的实例。应使用派生类的构造函数获取具有不同设置的实例。例如， UTF32Encoding 类提供可让你启用错误检测的构造函数。

另请参阅

适用于

GetEncoding(String, EncoderFallback, DecoderFallback)

Source:: Encoding.cs

Source:: Encoding.cs

Source:: Encoding.cs

返回与指定代码页名称关联的编码。参数指定一个错误处理程序，用于处理无法编码的字符和无法解码的字节序列。

public:
 static System::Text::Encoding ^ GetEncoding(System::String ^ name, System::Text::EncoderFallback ^ encoderFallback, System::Text::DecoderFallback ^ decoderFallback);

public static System.Text.Encoding GetEncoding (string name, System.Text.EncoderFallback encoderFallback, System.Text.DecoderFallback decoderFallback);

static member GetEncoding : string * System.Text.EncoderFallback * System.Text.DecoderFallback -> System.Text.Encoding

Public Shared Function GetEncoding (name As String, encoderFallback As EncoderFallback, decoderFallback As DecoderFallback) As Encoding

参数

name: String

首选编码的代码页名称。 WebName 属性返回的所有值均有效。可能值均在 Encoding 类主题中出现的表的“名称”一列中列出。

encoderFallback: EncoderFallback

一个对象，在无法用当前编码对字符进行编码时，该对象可用来提供错误处理过程。

decoderFallback: DecoderFallback

一个对象，在无法用当前编码对字节序列进行解码时，该对象可用来提供错误处理过程。

Encoding

与指定代码页关联的编码。

例外

ArgumentException

name 不是有效的代码页名称。

或

基础平台不支持 name 所指示的代码页。

示例

下面的示例演示 Encoding.GetEncoding(String, EncoderFallback, DecoderFallback) 方法。

// This example demonstrates the EncoderReplacementFallback class.

using namespace System;
using namespace System::Text;

int main()
{
    // Create an encoding, which is equivalent to calling the
    // ASCIIEncoding class constructor.
    // The EncoderReplacementFallback parameter specifies that the
    // string, "(unknown)", replace characters that cannot be encoded.
    // A decoder replacement fallback is also specified, but in this
    // code example the decoding operation cannot fail.

    Encoding^ ascii = Encoding::GetEncoding("us-ascii",
        gcnew EncoderReplacementFallback("(unknown)"),
        gcnew DecoderReplacementFallback("(error)"));

    // The input string consists of the Unicode characters LEFT POINTING
    // DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT
    // POINTING DOUBLE ANGLE QUOTATION MARK (U+00BB).
    // The encoding can only encode characters in the US-ASCII range of
    // U+0000 through U+007F. Consequently, the characters bracketing the
    // 'X' character are replaced with the fallback replacement string,
    // "(unknown)".

    String^ inputString = "\u00abX\u00bb";
    String^ decodedString;
    String^ twoNewLines = Environment::NewLine + Environment::NewLine;
    array <Byte>^ encodedBytes = 
        gcnew array<Byte>(ascii->GetByteCount(inputString));
    int numberOfEncodedBytes = 0;

    // ---------------------------------------------------------------------
        // Display the name of the encoding.
    Console::WriteLine("The name of the encoding is \"{0}\".{1}", 
        ascii->WebName, Environment::NewLine);

    // Display the input string in text.
    Console::WriteLine("Input string ({0} characters): \"{1}\"",
        inputString->Length, inputString);

    // Display the input string in hexadecimal.
    Console::Write("Input string in hexadecimal: ");
    for each (char c in inputString)
    {
        Console::Write("0x{0:X2} ", c);
    }
    Console::Write(twoNewLines);

    // ---------------------------------------------------------------------
    // Encode the input string.

    Console::WriteLine("Encode the input string...");
    numberOfEncodedBytes = ascii->GetBytes(inputString, 0, inputString->Length,
        encodedBytes, 0);

    // Display the encoded bytes.
    Console::WriteLine("Encoded bytes in hexadecimal ({0} bytes):{1}",
        numberOfEncodedBytes, Environment::NewLine);
    for(int i = 0; i < encodedBytes->Length; i++)
    {
        Console::Write("0x{0:X2} ", encodedBytes[i]);
        if(((i + 1) % 6) == 0)
        {
            Console::WriteLine();
        }
    }
    Console::Write(twoNewLines);

    // ---------------------------------------------------------------------
    // Decode the encoded bytes, yielding a reconstituted string.

    Console::WriteLine("Decode the encoded bytes...");
    decodedString = ascii->GetString(encodedBytes);

    // Display the input string and the decoded string for comparison.
    Console::WriteLine("Input string:  \"{0}\"", inputString);
    Console::WriteLine("Decoded string:\"{0}\"", decodedString);
}



/*
This code example produces the following results:

The name of the encoding is "us-ascii".

Input string (3 characters): "X"
Input string in hexadecimal: 0xAB 0x58 0xBB

Encode the input string...
Encoded bytes in hexadecimal (19 bytes):

0x28 0x75 0x6E 0x6B 0x6E 0x6F
0x77 0x6E 0x29 0x58 0x28 0x75
0x6E 0x6B 0x6E 0x6F 0x77 0x6E
0x29

Decode the encoded bytes...
Input string:  "X"
Decoded string:"(unknown)X(unknown)"

*/

// This example demonstrates the EncoderReplacementFallback class.

using System;
using System.Text;

class Sample
{
    public static void Main()
    {

// Create an encoding, which is equivalent to calling the
// ASCIIEncoding class constructor.
// The EncoderReplacementFallback parameter specifies that the
// string, "(unknown)", replace characters that cannot be encoded.
// A decoder replacement fallback is also specified, but in this
// code example the decoding operation cannot fail.

    Encoding ae = Encoding.GetEncoding(
                  "us-ascii",
                  new EncoderReplacementFallback("(unknown)"),
                  new DecoderReplacementFallback("(error)"));

// The input string consists of the Unicode characters LEFT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING
// DOUBLE ANGLE QUOTATION MARK (U+00BB).
// The encoding can only encode characters in the US-ASCII range of U+0000
// through U+007F. Consequently, the characters bracketing the 'X' character
// are replaced with the fallback replacement string, "(unknown)".

    string inputString = "\u00abX\u00bb";
    string decodedString;
    string twoNewLines = "\n\n";
    byte[] encodedBytes = new byte[ae.GetByteCount(inputString)];
    int numberOfEncodedBytes = 0;
    int ix = 0;

// --------------------------------------------------------------------------
// Display the name of the encoding.
    Console.WriteLine("The name of the encoding is \"{0}\".\n", ae.WebName);

// Display the input string in text.
    Console.WriteLine("Input string ({0} characters): \"{1}\"",
                       inputString.Length, inputString);

// Display the input string in hexadecimal.
    Console.Write("Input string in hexadecimal: ");
    foreach (char c in inputString.ToCharArray())
        {
        Console.Write("0x{0:X2} ", (int)c);
        }
    Console.Write(twoNewLines);

// --------------------------------------------------------------------------
// Encode the input string.

    Console.WriteLine("Encode the input string...");
    numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length,
                                       encodedBytes, 0);

// Display the encoded bytes.
    Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):\n",
                       numberOfEncodedBytes);
    ix = 0;
    foreach (byte b in encodedBytes)
        {
        Console.Write("0x{0:X2} ", (int)b);
        ix++;
        if (0 == ix % 6) Console.WriteLine();
        }
    Console.Write(twoNewLines);

// --------------------------------------------------------------------------
// Decode the encoded bytes, yielding a reconstituted string.

    Console.WriteLine("Decode the encoded bytes...");
    decodedString = ae.GetString(encodedBytes);

// Display the input string and the decoded string for comparison.
    Console.WriteLine("Input string:  \"{0}\"", inputString);
    Console.WriteLine("Decoded string:\"{0}\"", decodedString);
    }
}
/*
This code example produces the following results:

The name of the encoding is "us-ascii".

Input string (3 characters): "«X»"
Input string in hexadecimal: 0xAB 0x58 0xBB

Encode the input string...
Encoded bytes in hexadecimal (19 bytes):

0x28 0x75 0x6E 0x6B 0x6E 0x6F
0x77 0x6E 0x29 0x58 0x28 0x75
0x6E 0x6B 0x6E 0x6F 0x77 0x6E
0x29

Decode the encoded bytes...
Input string:  "«X»"
Decoded string:"(unknown)X(unknown)"

*/

' This example demonstrates the EncoderReplacementFallback class.
Imports System.Text

Class Sample
    Public Shared Sub Main() 
        
        ' Create an encoding, which is equivalent to calling the 
        ' ASCIIEncoding class constructor. 
        ' The EncoderReplacementFallback parameter specifies that the 
        ' string, "(unknown)", replace characters that cannot be encoded. 
        ' A decoder replacement fallback is also specified, but in this 
        ' code example the decoding operation cannot fail.  

        Dim erf As New EncoderReplacementFallback("(unknown)")
        Dim drf As New DecoderReplacementFallback("(error)")
        Dim ae As Encoding = Encoding.GetEncoding("us-ascii", erf, drf)
        
        ' The input string consists of the Unicode characters LEFT POINTING 
        ' DOUBLE ANGLE QUOTATION MARK (U+00AB), 'X' (U+0058), and RIGHT POINTING 
        ' DOUBLE ANGLE QUOTATION MARK (U+00BB). 
        ' The encoding can only encode characters in the US-ASCII range of U+0000 
        ' through U+007F. Consequently, the characters bracketing the 'X' character
        ' are replaced with the fallback replacement string, "(unknown)".

        Dim inputString As String = "«X»"
        Dim decodedString As String
        Dim twoNewLines As String = vbCrLf & vbCrLf
        Dim ix As Integer = 0
        Dim numberOfEncodedBytes As Integer = ae.GetByteCount(inputString)
        ' Counteract the compiler adding an extra byte to the array.
        Dim encodedBytes(numberOfEncodedBytes - 1) As Byte
        
        ' --------------------------------------------------------------------------
        ' Display the name of the encoding.
        Console.WriteLine("The name of the encoding is ""{0}""." & vbCrLf, ae.WebName)
        
        ' Display the input string in text.
        Console.WriteLine("Input string ({0} characters): ""{1}""", _
                           inputString.Length, inputString)
        
        ' Display the input string in hexadecimal. 
        ' Each element is converted to an integer with Convert.ToInt32.
        Console.Write("Input string in hexadecimal: ")
        Dim c As Char
        For Each c In inputString.ToCharArray()
            Console.Write("0x{0:X2} ", Convert.ToInt32(c))
        Next c
        Console.Write(twoNewLines)
        
        ' --------------------------------------------------------------------------
        ' Encode the input string. 
        Console.WriteLine("Encode the input string...")
        numberOfEncodedBytes = ae.GetBytes(inputString, 0, inputString.Length, _
                                           encodedBytes, 0)
        
        ' Display the encoded bytes. 
        ' Each element is converted to an integer with Convert.ToInt32.
        Console.WriteLine("Encoded bytes in hexadecimal ({0} bytes):" & vbCrLf, _
                           numberOfEncodedBytes)
        ix = 0
        Dim b As Byte
        For Each b In encodedBytes
            Console.Write("0x{0:X2} ", Convert.ToInt32(b))
            ix += 1
            If 0 = ix Mod 6 Then
                Console.WriteLine()
            End If
        Next b
        Console.Write(twoNewLines)
        
        ' --------------------------------------------------------------------------
        ' Decode the encoded bytes, yielding a reconstituted string.
        Console.WriteLine("Decode the encoded bytes...")
        decodedString = ae.GetString(encodedBytes)
        
        ' Display the input string and the decoded string for comparison.
        Console.WriteLine("Input string:  ""{0}""", inputString)
        Console.WriteLine("Decoded string:""{0}""", decodedString)
    
    End Sub
End Class
'
'This code example produces the following results:
'
'The name of the encoding is "us-ascii".
'
'Input string (3 characters): "X"
'Input string in hexadecimal: 0xAB 0x58 0xBB
'
'Encode the input string...
'Encoded bytes in hexadecimal (19 bytes):
'
'0x28 0x75 0x6E 0x6B 0x6E 0x6F
'0x77 0x6E 0x29 0x58 0x28 0x75
'0x6E 0x6B 0x6E 0x6F 0x77 0x6E
'0x29
'
'Decode the encoded bytes...
'Input string:  "X"
'Decoded string:"(unknown)X(unknown)"
'

注解

在 .NET 5 及更高版本中，不支持代码页名称 utf-7 。

注意

ANSI 代码页在不同计算机上可能不同，并且可以在一台计算机上更改，导致数据损坏。为获得最一致的结果，应使用 Unicode 编码，例如 UTF-8 （代码页65001）或 UTF-16，而不是使用特定的代码页。

GetEncoding使用默认设置返回缓存的实例。应使用派生类的构造函数获取具有不同设置的实例。例如， UTF32Encoding 类提供可让你启用错误检测的构造函数。

另请参阅

适用于

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