图片转base64格式，base64生成图片

最新推荐文章于 2025-05-19 21:41:37 发布

原创最新推荐文章于 2025-05-19 21:41:37 发布 · 873 阅读

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本文介绍了一个使用C++实现的Base64编码和解码方法，用于处理图片文件。具体包括如何将图片文件转换为Base64字符串以及如何从Base64字符串还原图片。文中还提供了具体的编码表和解码表，并展示了读取和写入图片文件的具体步骤。

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std::string CBASE64T0MIMAGEDlg::Encode(const char* Data, int DataByte)
{
   //编码表
   const char EncodeTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   //返回值
   string strEncode;
   unsigned char Tmp[4] = { 0 };
   int LineLength = 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];
       if (LineLength += 4, LineLength == 76) { strEncode += "\r\n"; LineLength = 0; }
   }
   //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;
}

std::string CBASE64T0MIMAGEDlg::Decode(const char* Data, int DataByte, int& OutByte)
{
   //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
   string strDecode;
   int nValue;
   int i = 0;
   while (i < DataByte)
   {
       if (*Data != '\r' && *Data != '\n')
       {
           nValue = DecodeTable[*Data++] << 18;
           nValue += DecodeTable[*Data++] << 12;
           strDecode += (nValue & 0x00FF0000) >> 16;
           OutByte++;
           if (*Data != '=')
           {
               nValue += DecodeTable[*Data++] << 6;
               strDecode += (nValue & 0x0000FF00) >> 8;
               OutByte++;
               if (*Data != '=')
               {
                   nValue += DecodeTable[*Data++];
                   strDecode += nValue & 0x000000FF;
                   OutByte++;
               }
           }
           i += 4;
       }
       else// 回车换行,跳过
       {
           Data++;
           i++;
       }
   }
   return strDecode;
}

// 以下是读写图片的调用代码：
bool CBASE64T0MIMAGEDlg::ReadPhotoFile(std::basic_string<TCHAR> strFileName,std::string &strData ,int * dataSize)
{
HANDLE hFile;
hFile = CreateFile(strFileName.c_str(), GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

   if (hFile == INVALID_HANDLE_VALUE)
   {
       return false;
   }

   DWORD dFileSize = GetFileSize(hFile, NULL);
   byte * pBuffer = new byte[dFileSize + 1];

if(pBuffer == NULL)
return false;

memset(pBuffer, 0, dFileSize);

   DWORD dReadSize(0);
   if (!ReadFile(hFile, pBuffer, dFileSize, &dReadSize, NULL))
   {
   delete[]pBuffer;
       CloseHandle(hFile);
       return false;
   }

   strData = "";
   *dataSize = *(&dFileSize);

   strData = Encode((const char*)pBuffer, dReadSize);

   delete[]pBuffer;
   CloseHandle(hFile);
   return true;
}

bool CBASE64T0MIMAGEDlg::WritePhotoFile(std::basic_string<TCHAR> strFileName, std::string &strData)
{
HANDLE hFile;
hFile = CreateFile(strFileName.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

   if (hFile == INVALID_HANDLE_VALUE)
   {
       return false;
   }

   int datalen(0);
   DWORD dwritelen(0);
   std::string strdcode = Decode(strData.data(),strData.size(), datalen);
   if (!WriteFile(hFile, strdcode.data(), datalen, &dwritelen, NULL))
   {
       CloseHandle(hFile);
       return false;
   }
   CloseHandle(hFile);
   return true;
}

void CBASE64T0MIMAGEDlg::OnBnClickedButton1()
{
   BOOL bRead =FALSE;
   int frontlen =0;
   bRead = ReadPhotoFile("D:\\Data\\Image\\back.jpg",strData,&frontlen);
}

void CBASE64T0MIMAGEDlg::OnBnClickedButton2()
{
BOOL bWrite= FALSE;
bWrite = WritePhotoFile("D:\\ABC.jpg",strData);
}

来源：http://www.cnblogs.com/jeray/p/8746976.html

https://blog.youkuaiyun.com/m0_37263637/article/details/79559097