C# 判断txt文件编码格式

   /// <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;}}