将（二进制）byte[]型转换成字符串

 public string ByteToString(byte[] br)
    {
        System.Text.StringBuilder sb = new StringBuilder(2048);
        foreach (byte b in br)
        {
            sb.Append(b > 15 ? Convert.ToString(b, 2) : '0' + Convert.ToString(b, 2));
        }
        return sb.ToString();
    }