標頭檔案h

#include <string>
using namespace std;

class ZBase64
{
public:
    /*編碼
    DataByte
        [in]輸入的資料長度,以位元組為單位
    */
    string Encode(const unsigned char* Data,int DataByte);
    /*解碼
    DataByte
        [in]輸入的資料長度,以位元組為單位
    OutByte
        [out]輸出的資料長度,以位元組為單位,請不要通過返回值計算
        輸出資料的長度
    */
    string Decode(const char* Data,int DataByte,int& OutByte);
};

實現檔案cpp

#include "stdAfx.h"
#include "ZBase64.h"

string ZBase64::Encode(const unsigned char* Data,int DataByte)
{
    //編碼表
    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;}
    }
    //對剩餘資料進行編碼
    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;
}

string ZBase64::Decode(const char* Data,int DataByte,int& OutByte)
{
    //解碼錶
    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// 回車換行,跳過
        {
            Data++;
            i++;
        }
     }
    return strDecode;
}

使用例子，對圖片進行編碼：

CString CScanDlg::EncodeImage()
{//對圖片進行Base64編碼
    ZBase64 zBase;
    //圖片編碼
    CxImage  image;   // 定義一個CxImage物件   
    image.Load(this->m_strImgPath, CXIMAGE_FORMAT_JPG);   //先裝載jpg檔案,需要指定檔案型別
    long size=0;//得到影象大小
    BYTE* buffer=0;//儲存影象資料的緩衝
    image.Encode(buffer,size,CXIMAGE_FORMAT_JPG);//把image物件中的影象以type型別資料copy到buffer
    string strTmpResult=zBase.Encode(buffer,size);
    CString result;
    result = strTmpResult.c_str();
    return result;
}

對編碼後的圖片進行解碼：

void CScanDlg::DecodeImageData(CString strData)
{//對Base64編碼過的資料解碼並顯示原圖片

    ZBase64 zBase;
    int OutByte=0;
    string strTmpResult=zBase.Decode(strData,strData.GetLength(),OutByte);
    int i,len = strTmpResult.length();
    BYTE *buffer = new BYTE[len];
    for (i=0;i<len;++i)
    {
        buffer[i] = strTmpResult[i];
    }
    CxImage image(buffer,len,CXIMAGE_FORMAT_JPG);//把記憶體緩衝buffer中的資料構造成Image物件
    delete [] buffer;
    CDC* hdc = m_picture.GetDC();
    m_bitmap = image.MakeBitmap(hdc->m_hDC);
    HBITMAP h0ldBmp = m_picture.SetBitmap(m_bitmap);
    if(h0ldBmp) DeleteObject(h0ldBmp);
    if(hdc->m_hDC) m_picture.ReleaseDC(hdc);
    if(m_bitmap) DeleteObject(m_bitmap);
}

關於Base64編碼，看下邊的百科：