c#中识别 文本字符编码的类

一个不多的 编码识别类

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;



namespace xingminggongju

{

    /// <summary>

    /// 获取文件的编码格式

    /// </summary>

    public class EncodingType

    {

        /// <summary>

        /// 给定文件的路径，读取文件的二进制数据，判断文件的编码类型

        /// </summary>

        /// <param name="FILE_NAME">文件路径</param>

        /// <returns>文件的编码类型</returns>

        public static System.Text.Encoding GetType(string FILE_NAME)

        {

            FileStream fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read);

            Encoding r = GetType(fs);

            fs.Close();

            return r;

        }



        /// <summary>

        /// 通过给定的文件流，判断文件的编码类型

        /// </summary>

        /// <param name="fs">文件流</param>

        /// <returns>文件的编码类型</returns>

        public static System.Text.Encoding GetType(FileStream fs)

        {

            byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };

            byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };

            byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM

            Encoding reVal = Encoding.Default;



            BinaryReader r = new BinaryReader(fs, System.Text.Encoding.Default);

            int i;

            int.TryParse(fs.Length.ToString(), out i);

            byte[] ss = r.ReadBytes(i);

            if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))

            {

                reVal = Encoding.UTF8;

            }

            else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)

            {

                reVal = Encoding.BigEndianUnicode;

            }

            else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)

            {

                reVal = Encoding.Unicode;

            }

            r.Close();

            return reVal;



        }



        /// <summary>

        /// 判断是否是不带 BOM 的 UTF8 格式

        /// </summary>

        /// <param name="data"></param>

        /// <returns></returns>

        private static bool IsUTF8Bytes(byte[] data)

        {

            int charByteCounter = 1;　 //计算当前正分析的字符应还有的字节数

            byte curByte; //当前分析的字节.

            for (int i = 0; i < data.Length; i++)

            {

                curByte = data[i];

                if (charByteCounter == 1)

                {

                    if (curByte >= 0x80)

                    {

                        //判断当前

                        while (((curByte <<= 1) & 0x80) != 0)

                        {

                            charByteCounter++;

                        }

                        //标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　

                        if (charByteCounter == 1 || charByteCounter > 6)

                        {

                            return false;

                        }

                    }

                }

                else

                {

                    //若是UTF-8 此时第一位必须为1

                    if ((curByte & 0xC0) != 0x80)

                    {

                        return false;

                    }

                    charByteCounter--;

                }

            }

            if (charByteCounter > 1)

            {

                throw new Exception("非预期的byte格式");

            }

            return true;

        }



    }

}