Question

System.Text.Encoding使用了哪个CharSet.Ansi？

我想解码.NET Core应用程序中的字符串（之前由C ++代码编组），而不定义结构并使用Marshal.PtrToStructure。

Encoding.GetEncoding(???).GetString(...)

在.NET Framework应用程序System.Text.Encoding.Default中起作用：

[StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
public struct Structure
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
    public string FieldA;
}

public class Net461App
{
    static void Main(string[] args)
    {
        var @struct = new Structure { FieldA = "äöüß" };
        byte[] buffer = ToByteArray(@struct);
        var unmarshalled = ToStructure<Structure>(buffer).FieldA;                     // "äöüß"

        Console.WriteLine(Encoding.Default.GetString(buffer).Trim('\0'));             // "äöüß"
        Console.WriteLine(Encoding.Default.EncodingName);                             // Western European (Windows)                    
        Console.WriteLine(Encoding.Default.CodePage);                                 // 1252

        int ansiCodePage = Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage; // 1252
        Encoding ansiEncoding = Encoding.GetEncoding(ansiCodePage);                   // works
        Console.WriteLine(ansiEncoding.GetString(buffer).Trim('\0'));                 // "äöüß"
        Console.WriteLine(ansiEncoding.EncodingName);                                 // Western European (Windows) 
        Console.WriteLine(ansiEncoding.CodePage);                                     // 1252 
    }

    public static byte[] ToByteArray<T>(T structure) where T : struct
    {
        var buffer = new byte[Marshal.SizeOf(structure)];
        IntPtr handle = Marshal.AllocHGlobal(buffer.Length);
        try
        {
            Marshal.StructureToPtr(structure, handle, true);
            Marshal.Copy(handle, buffer, 0, buffer.Length);
            return buffer;
        }
        finally
        {
            Marshal.FreeHGlobal(handle);
        }

    }

    public static T ToStructure<T>(byte[] buffer) where T : struct
    {
        IntPtr handle = Marshal.AllocHGlobal(buffer.Length);
        try
        {
            Marshal.Copy(buffer, 0, handle, buffer.Length);
            return Marshal.PtrToStructure<T>(handle);
        }
        finally
        {
            Marshal.FreeHGlobal(handle);
        }

    }
}

Encoding.Default与Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage相同，它们都生成与CharSet.Ansi相同的字符串。但TextInfo.ANSICodePage始终与CharSet.Ansi相同吗？

Encoding.Default在.NET Core中有所不同，并且不支持代码页1252：

public class NetCore2App
{
    static void Main(string[] args)
    {
        var @struct = new Structure { FieldA = "äöüß" };
        byte[] buffer = ToByteArray(@struct);
        var unmarshalled = ToStructure<Structure>(buffer).FieldA;                     // "äöüß"

        Console.WriteLine(Encoding.Default.GetString(buffer).Trim('\0'));             // "????"
        Console.WriteLine(Encoding.Default.EncodingName);                             // Unicode(UTF - 8)                
        Console.WriteLine(Encoding.Default.CodePage);                                 // 65001

        int ansiCodePage = Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage; // 1252
        Encoding ansiEncoding = Encoding.GetEncoding(ansiCodePage);                   // throws "No data is available for encoding 1252."
        Console.WriteLine(ansiEncoding.GetString(buffer).Trim('\0'));                 // ...
        Console.WriteLine(ansiEncoding.EncodingName);                                 // ...
        Console.WriteLine(ansiEncoding.CodePage);                                     // ...
    }
    // ...
}

更新

调查使用System.Text.Encoding.CodePages的建议我发现以下有关获取系统当前ANSI代码页的提示：

Encoding.GetEncoding

以下似乎有效：

Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
int currentAnsiCodePage = Encoding.GetEncoding(0).CodePage;
Encoding encoding = Encoding.GetEncoding(currentAnsiCodePage);

以下各项为我提供了相同的代码页，可以正确解码我的测试中的字符串

Encoding.GetEncoding（0）.CodePage（需要CodePagesEncodingProvider注册）
Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage
CultureInfo.CurrentCulture.TextInfo.ANSICodePage

不确定哪一个更适合并适用于所有机器。

CharSet.Ansi使用哪种编码？

0 个答案: