base64处理类

base64是日常开发中经常使用的编码方式，在.net,java甚至php中都有简单的类库或函数直接调用，唯独c++中没有可用的资源，没有办法，谁让c++灵活呢，自己动手开发一个吧。

base64的原理很简单，无须赘述，google一下，一大堆，但是好用的有算法精妙的代码着实不多，自己动脑又太费神，找个成熟的其他语言的类翻译一下吧，嗯，c#的语法与c++很相似，ok，抄袭一下。不再啰嗦，直接看代码吧。

 

头文件代码如下（base64.h）：

#if !defined(AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_)
#define AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

class CBase64
{
public:
static int ToBase64String(char* & pOut,char * pIn,int nLen);
static int FromBase64String(char * & pOut,char * pIn);
CBase64();
virtual ~CBase64();
protected:
static int CalculateOutputLength(int inputLength);
static int ConvertToBase64(char* outChars, char* inData, int length);
static char char2sixbit(char c);
};

#endif // !defined(AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_)

cpp文件代码如下：

// Base641.cpp: implementation of the CBase64 class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Base64.h"
#include <string.h>
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
static char base64Table[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
CBase64::CBase64()
{

}

CBase64::~CBase64()
{

}
int CBase64::CalculateOutputLength(int inputLength)
{
int num1 = (inputLength / 3) * 4;
num1 += ((inputLength % 3) != 0) ? 4 : 0;
if (num1 == 0)
{
return num1;
}
int num2 = num1 / 0x4c;
if ((num1 % 0x4c) == 0)
{
num2--;
}
return (num1 + (num2 * 2));
}
int CBase64::ConvertToBase64(char* outChars, char* inData, int length)
{
int num1 = length % 3;
int num2 = length - num1;
int num3 = 0;
int num4 = 0;
char* chRef1 = base64Table;

int num5 = 0;
while (num5 < num2)
{

outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
outChars[num3 + 1] = chRef1[((inData[num5] & 3) << 4) | ((inData[num5 + 1] & 240) >> 4)];
outChars[num3 + 2] = chRef1[((inData[num5 + 1] & 15) << 2) | ((inData[num5 + 2] & 0xc0) >> 6)];
outChars[num3 + 3] = chRef1[inData[num5 + 2] & 0x3f];
num3 += 4;
num5 += 3;
}
num5 = num2;

switch (num1)
{
case 1:
break;

case 2:
outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
outChars[num3 + 1] = chRef1[((inData[num5] & 3) << 4) | ((inData[num5 + 1] & 240) >> 4)];
outChars[num3 + 2] = chRef1[(inData[num5 + 1] & 15) << 2];
outChars[num3 + 3] = chRef1[0x40];
num3 += 4;
goto Label_0220;

default:
goto Label_0220;
}
outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
outChars[num3 + 1] = chRef1[(inData[num5] & 3) << 4];
outChars[num3 + 2] = chRef1[0x40];
outChars[num3 + 3] = chRef1[0x40];
num3 += 4;

Label_0220:;
return num3;
}

int CBase64::ToBase64String(char* & pOut, char *pIn, int nLen)
{
int nOut = CalculateOutputLength(nLen);
pOut = new char[nOut + 1];
int n = ConvertToBase64(pOut,pIn,nLen);
pOut[n] = '/0';
return n;
}
int CBase64::FromBase64String(char * & pOut,char * pIn)
{
int temp = 0;
int length2, length3;
int blockCount;
int paddingCount;
int length = strlen(pIn);

//find how many padding are there
for (int x = 0; x < 2; x++)
{
if (pIn[length - x - 1] == '=')
temp++;
}
paddingCount = temp;
blockCount = length / 4;
length2 = blockCount * 3;

char * buffer = new char[length];//first conversion result
char * buffer2 = new char[length2];//decoded array with padding
for ( x = 0; x < length; x++)
{
buffer[x] = char2sixbit(pIn[x]);
}

char b, b1, b2, b3;
char temp1, temp2, temp3, temp4;

for (x = 0; x < blockCount; x++)
{
temp1 = buffer[x * 4];
temp2 = buffer[x * 4 + 1];
temp3 = buffer[x * 4 + 2];
temp4 = buffer[x * 4 + 3];

b = (char)(temp1 << 2);
b1 = (char)((temp2 & 48) >> 4);
b1 += b;

b = (char)((temp2 & 15) << 4);
b2 = (char)((temp3 & 60) >> 2);
b2 += b;

b = (char)((temp3 & 3) << 6);
b3 = temp4;
b3 += b;

buffer2[x * 3] = b1;
buffer2[x * 3 + 1] = b2;
buffer2[x * 3 + 2] = b3;
}
//remove paddings
length3 = length2 - paddingCount;
pOut = new char[length3];

for (x = 0; x < length3; x++)
{
pOut[x] = buffer2[x];
}
delete[] buffer;
delete[] buffer2;
return length3;
}

char CBase64::char2sixbit(char c)
{

if (c == '=')
return 0;
else
{
for (int x = 0; x < 64; x++)
{
if (base64Table[x] == c)
return x;
}
//should not reach here
return 0;
}
}

怎么样？还算精炼吧。