EncodingHelper Identify Encoding by BOM

namespace Microshaoft
{
    using System.IO;
    using System.Text;
    using System.Collections.Generic;
    public static class EncodingHelper
    {
        public static Encoding IdentifyEncoding
                                    (
                                        Stream stream
                                        , Encoding defaultEncoding
                                        , Encoding[] identifyEncodings
                                    )
        {
            byte[] data = StreamDataHelper.ReadDataToBytes(stream);
            return IdentifyEncoding
                        (
                            data
                            , defaultEncoding
                            , identifyEncodings
                        );
        }
        public static Encoding IdentifyEncoding
                                    (
                                        Stream stream
                                        , Encoding defaultEncoding
                                    )
        {
            byte[] data = StreamDataHelper.ReadDataToBytes(stream);
            return IdentifyEncoding
                        (
                            data
                            , defaultEncoding
                        );
        }
        public static Encoding IdentifyEncoding
                                    (
                                        byte[] data
                                        , Encoding defaultEncoding
                                    )
        {
            EncodingInfo[] encodingInfos = Encoding.GetEncodings();
            List<Encoding> list = new List<Encoding>();
            foreach (EncodingInfo info in encodingInfos)
            {
                Encoding e = info.GetEncoding();
                if (e.GetPreamble().Length > 0)
                {
                    list.Add(e);
                    System.Console.WriteLine(e.EncodingName);
                }
            }
            Encoding[] encodings = new Encoding[list.Count];
            list.CopyTo(encodings);
            return IdentifyEncoding
                        (
                            data
                            , defaultEncoding
                            , encodings
                        );
        }
        public static Encoding IdentifyEncoding
                                    (
                                        byte[] data
                                        , Encoding defaultEncoding
                                        , Encoding[] identifyEncodings
                                    )
        {
            Encoding encoding = defaultEncoding;
            foreach (Encoding e in identifyEncodings)
            {
                byte[] buffer = e.GetPreamble();
                int l = buffer.Length;
                if (l == 0)
                {
                    continue;
                }
                bool flag = false;
                for (int i = 0; i < l; i++)
                {
                    if (buffer[i] != data[i])
                    {
                        flag = true;
                        break;
                    }
                }
                if (flag)
                {
                    continue;
                }
                else
                {
                    encoding = e;
                }
            }
            return encoding;
        }
    }
}
namespace Microshaoft
{
    using System.IO;
    public static class StreamDataHelper
    {
        public static byte[] ReadDataToBytes(Stream stream)
        {
            byte[] buffer = new byte[64 * 1024];
            MemoryStream ms = new MemoryStream();
            int r = 0;
            int l = 0;
            long position = -1;
            if (stream.CanSeek)
            {
                position = stream.Position;
                stream.Position = 0;
            }
            while (true)
            {
                r = stream.Read(buffer, 0, buffer.Length);
                if (r > 0)
                {
                    l += r;
                    ms.Write(buffer, 0, r);
                }
                else
                {
                    break;
                }
            }
            byte[] bytes = new byte[l];
            ms.Position = 0;
            ms.Read(bytes, 0, (int) l);
            ms.Close();
            ms.Dispose();
            ms = null;
            if (position >= 0)
            {
                stream.Position = position;
            }
            return bytes;
        }
    }
}