C#简单判断字符编码的方法

public static string GetText(byte[] buff){  string strReslut = string.Empty;  if (buff.Length > 3)  {    if (buff[0] == 239 && buff[1] == 187 && buff[2] == 191)    {// utf-8      strReslut = Encoding.UTF8.GetString(buff);    }    else if (buff[0] == 254 && buff[1] == 255)    {// big endian unicode      strReslut = Encoding.BigEndianUnicode.GetString(buff);    }    else if (buff[0] == 255 && buff[1] == 254)    {// unicode      strReslut = Encoding.Unicode.GetString(buff);    }    else if (isUtf8(buff))    {// utf-8      strReslut = Encoding.UTF8.GetString(buff);    }    else    {// ansi      strReslut = Encoding.Default.GetString(buff);    }  }  return strReslut;}// 110XXXXX, 10XXXXXX// 1110XXXX, 10XXXXXX, 10XXXXXX// 11110XXX, 10XXXXXX, 10XXXXXX, 10XXXXXXprivate static bool isUtf8(byte[] buff){  for (int i = 0; i < buff.Length; i++)  {    if ((buff[i] & 0xE0) == 0xC0) // 110x xxxx 10xx xxxx    {      if ((buff[i + 1] & 0x80) != 0x80)      {        return false;      }    }    else if ((buff[i] & 0xF0) == 0xE0) // 1110 xxxx 10xx xxxx 10xx xxxx    {      if ((buff[i + 1] & 0x80) != 0x80 || (buff[i + 2] & 0x80) != 0x80)      {        return false;      }    }    else if ((buff[i] & 0xF8) == 0xF0) // 1111 0xxx 10xx xxxx 10xx xxxx 10xx xxxx    {      if ((buff[i + 1] & 0x80) != 0x80 || (buff[i + 2] & 0x80) != 0x80 || (buff[i + 3] & 0x80) != 0x80)      {        return false;      }    }  }  return true;}// news.sohu.comprivate static bool isGBK(byte[] buff){  return false;}