UE4 C++ Base64编解码

FString AUniqueID::Base64Encode(const unsigned char* Data, int DataByte)
{
    
    
  //编码表
  const char EncodeTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  //返回值
  FString strEncode;
  unsigned char Tmp[4] = {
    
     0 };
  for (int i = 0; i<(int)(DataByte / 3); i++)
  {
    
    
    Tmp[1] = *Data++;
    Tmp[2] = *Data++;
    Tmp[3] = *Data++;
    strEncode += EncodeTable[Tmp[1] >> 2];
    strEncode += EncodeTable[((Tmp[1] << 4) | (Tmp[2] >> 4)) & 0x3F];
    strEncode += EncodeTable[((Tmp[2] << 2) | (Tmp[3] >> 6)) & 0x3F];
    strEncode += EncodeTable[Tmp[3] & 0x3F];
  }
  //对剩余数据进行编码
  int Mod = DataByte % 3;
  if (Mod == 1)
  {
    
    
    Tmp[1] = *Data++;
    strEncode += EncodeTable[(Tmp[1] & 0xFC) >> 2];
    strEncode += EncodeTable[((Tmp[1] & 0x03) << 4)];
    strEncode += "==";
  }
  else if (Mod == 2)
  {
    
    
    Tmp[1] = *Data++;
    Tmp[2] = *Data++;
    strEncode += EncodeTable[(Tmp[1] & 0xFC) >> 2];
    strEncode += EncodeTable[((Tmp[1] & 0x03) << 4) | ((Tmp[2] & 0xF0) >> 4)];
    strEncode += EncodeTable[((Tmp[2] & 0x0F) << 2)];
    strEncode += "=";
  }

  return strEncode;
}

void AUniqueID::Base64Decode(const char* Data, int DataByte, TArray<BYTE>& OutData)
{
    
    
  //解码表
  const char DecodeTable[] =
  {
    
    
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    62, // '+'
    0, 0, 0,
    63, // '/'
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // '0'-'9'
    0, 0, 0, 0, 0, 0, 0,
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
    13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 'A'-'Z'
    0, 0, 0, 0, 0, 0,
    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // 'a'-'z'
  };
  //返回值
  int nValue;
  int i = 0;
  while (i < DataByte)
  {
    
    
    if (*Data != '\r' && *Data != '\n')
    {
    
    
      nValue = DecodeTable[*Data++] << 18;
      nValue += DecodeTable[*Data++] << 12;
      OutData.Add((nValue & 0x00FF0000) >> 16);
      if (*Data != '=')
      {
    
    
        nValue += DecodeTable[*Data++] << 6;
        OutData.Add((nValue & 0x0000FF00) >> 8);
        if (*Data != '=')
        {
    
    
          nValue += DecodeTable[*Data++];
          OutData.Add(nValue & 0x000000FF);
        }
      }
      i += 4;
    }
    else// 回车换行,跳过
    {
    
    
      Data++;
      i++;
    }
  }
}