C++实现base64编码

/*base_64.h文件*/
#ifndef BASE_64_H
#define BASE_64_H
/**
 * Base64 编码/解码
 * @author liruixing
 */
class Base64{
private:
    std::string _base64hash;
    int _encode_data;
    int _decode_data;
    int _width;
    bool _debug;
    std::string _encode_result,_decode_result;

    void _encode_func(int bin,int bytes = 3);
    void _decode_func(int bin,int bytes = 2);
public:
    Base64()
    {
        _base64hash = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; /*这是Base64编码使用的标准字典*/
        _encode_data = 0xfc0000;
        _decode_data = 0xff0000;
        _width       = 0xffffff;
        _debug      = false;
    }
    /**
     * 这里必须是unsigned类型，否则编码中文的时候出错
     */
    std::string Encode(const unsigned char * str,int bytes);
    std::string Decode(const char *str,int bytes);
    void Debug(bool open = true);
};
#endif

/*base_64.cpp文件*/
#include <iostream>
#include <string>
#include <cstring>
#include "base_64.h"
void Base64::_encode_func(int bin,int bytes) {
        int num = 3,matches = 0,bits1=0,bits2=0,result=0;
        bits1 = (num - bytes) * 6;
            bits2 = bytes * 6;
            matches = _encode_data >> bits1;
        while( matches ) {
            result = bin & matches;
            result = result >> bits2;
            bytes--;
            bits1 = (num - bytes) * 6;
            bits2 = bytes * 6;
            matches = _encode_data >> bits1;
            if(_debug) {
                printf("result = %d , hex = %x\n",result,result);
            }
            _encode_result += _base64hash[result];
        }
    }

void Base64::_decode_func(int bin,int bytes) {
    int num = 2,matches = 0,bits1=0,bits2=0,result=0;
    bits1 = (num - bytes) * 8;
    bits2 = bytes * 8;
    matches = _decode_data >> bits1;
    while( matches ) {
        result = bin & matches;
        result = result >> bits2;
        bytes--;
        bits1 = (num - bytes) * 8;
        bits2 = bytes * 8;
        matches = _decode_data >> bits1;
        if(_debug) {
            printf("result = %d , hex = %x\n",result,result);
        }
        _decode_result += (char)result;
    }
}

std::string Base64::Encode(const unsigned char * str,int bytes) {
    int num = 0,bin = 0,i;
    if(bytes >= 3) {
        for(i=0;i<bytes;i++) {
            bin = bin << 8;
            if(_debug) {
                printf("bin = %d , hex = %x\n",bin,str[i]);
            }
            bin = bin | (int)str[i];
            if((i+1)%3 == 0) {
                _encode_func(bin,3);
                bin = 0;
            }
        }
    }
    if(bytes%3 == 1) {
        bin = (int)str[bytes-1];
        bin = bin << 4;
        _encode_func(bin,1);
        _encode_result += "==";
    } else if(bytes%3 == 2) {
        bin = (int)str[bytes-2];
        bin = bin << 8;
        bin = bin | (int)str[bytes-1];
        bin = bin << 2;
        _encode_func(bin,2);
        _encode_result += "=";
    }
    return _encode_result;
}
std::string Base64::Decode(const char *str,int bytes) {
    //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‘
    };
    int bin = 0,i,pos=0;
    char *_decode_string = new char[bytes];
    strcpy(_decode_string,str);
    while(_decode_string[bytes-1] == ‘=‘)
    {
        _decode_string[bytes-1] = ‘\0‘;
        bytes--;
    }
    if(bytes >= 4) {
        for(i=0;i<bytes;i++) {
            bin = bin << 6;
            pos = DecodeTable[(int)_decode_string[i]];
            if(_debug) {
                printf("bin = %d , binary = %x-----ch = %c\n",bin,pos,_decode_string[i]);
            }
            bin = bin | pos;
            if((i+1)%4 == 0) {
                _decode_func(bin);
                bin = 0;
            }
        }
    }
    if(bytes%4 == 3) {
        bin = 0;
        if(_debug) {
            printf("bin = %x , ch = %c\n",bin, _decode_string[bytes-3]);
        }
        pos = DecodeTable[(int)_decode_string[bytes-3]];
        bin = bin | pos;
        bin = bin << 6;
        if(_debug) {
            printf("bin = %x , ch = %c\n",bin, _decode_string[bytes-2]);
        }
        pos = DecodeTable[(int)_decode_string[bytes-2]];
        bin = bin | pos;
        bin = bin << 6;
        if(_debug) {
            printf("bin = %x , ch = %c\n",bin, _decode_string[bytes-1]);
        }
        pos = DecodeTable[(int)_decode_string[bytes-1]];
        bin = bin | pos;
        if(_debug) {
            printf("bin = %x\n",bin);
        }
        bin = bin >> 2;
        _decode_func(bin,1);
    } else if(bytes%4 == 2) {
        bin = 0;
        if( _debug ) {
            printf("bin = %x , ch = %c\n",bin, _decode_string[bytes-2]);
        }
        pos = DecodeTable[(int)_decode_string[bytes-2]];
        bin = bin | pos;
        bin = bin << 6;
        if( _debug ) {
            printf("bin = %x , ch = %c\n",bin, _decode_string[bytes-1]);
        }
        pos = DecodeTable[(int)_decode_string[bytes-1]];
        bin = bin | pos;
        bin = bin >> 4;
        _decode_func(bin,0);
    }
    delete [] _decode_string;
    return _decode_result;
}
void Base64::Debug(bool open) {
    _debug = open;
}

g++ -c base_64.cpp
ar rs libbase_64.a base_64.o

/*main.cppe文件*/
#include <iostream>
#include "base_64.h"

using namespace std;
int main()
{
    unsigned char str[] = "这是一条测试数据：http://img.v.cmcm.com/7dd6e6d7-0c2d-5a58-a072-71f828b94cbc_crop_216x150.jpg";
    string normal,encoded;
    int i,len = sizeof(str)-1;
    Base64 *base = new Base64();
    encoded = base->Encode(str,len);
    cout << "base64 encode : " << encoded << endl;
    len = encoded.length();
    const char * str2 = encoded.c_str();
    normal = base->Decode(str2,len);
    cout << "base64 decode : " << normal <<endl;
    return 0;
}

g++ main.cpp -L. -lbase_64 -Ibase_64 -o main
./main