字符集之间转换(UTF-8,UNICODE,Gb2312)

特搜集了UTF-8,UNICODE,Gb2312他们3个之间的相互转换.

UTF-8:   3字节一个字符
UNICODE: 2字节一个字符
GB2312:  1字节一个字符

例子：

“你”字的UTF-8编码: E4 BD A0　　　　　　　　11100100 10111101 10100000
“你”的Unicode编码: 4F 60　　　　　　　　　   01001111 01100000
按照UTF-8的编码规则，分解如下：xxxx0100 xx111101 xx100000
把除了x之外的数字拼接在一起，就变成“你”的Unicode编码了。
注意UTF-8的最前面３个1，表示整个UTF-8串是由３个字节构成的。
经过UTF-8编码之后，再也不会出现敏感字符了，因为最高位始终为1。

类定义
class CChineseCode
{
   public:
       static void UTF_8ToUnicode(wchar_t* pOut,char *pText);  // 把UTF-8转换成Unicode
       static void UnicodeToUTF_8(char* pOut,wchar_t* pText);  //Unicode 转换成UTF-8
       static void UnicodeToGB2312(char* pOut,wchar_t uData);  // 把Unicode 转换成 GB2312
       static void Gb2312ToUnicode(wchar_t* pOut,char *gbBuffer);// GB2312 转换成　Unicode
       static void GB2312ToUTF_8(string& pOut,char *pText, int pLen);//GB2312 转为 UTF-8
       static void UTF_8ToGB2312(string &pOut, char *pText, int pLen);//UTF-8 转为 GB2312
};

类实现

void CChineseCode::UTF_8ToUnicode(wchar_t* pOut,char *pText)
{
    char* uchar = (char *)pOut;

    uchar[1] = ((pText[0] & 0x0F) << 4) + ((pText[1] >> 2) & 0x0F);
    uchar[0] = ((pText[1] & 0x03) << 6) + (pText[2] & 0x3F);

    return;
}

void CChineseCode::UnicodeToUTF_8(char* pOut,wchar_t* pText)
{
    // 注意 WCHAR高低字的顺序,低字节在前，高字节在后
    char* pchar = (char *)pText;

    pOut[0] = (0xE0 | ((pchar[1] & 0xF0) >> 4));
    pOut[1] = (0x80 | ((pchar[1] & 0x0F) << 2)) + ((pchar[0] & 0xC0) >> 6);
    pOut[2] = (0x80 | (pchar[0] & 0x3F));

    return;
}

void CChineseCode::UnicodeToGB2312(char* pOut,wchar_t uData)
{
    WideCharToMultiByte(CP_ACP,NULL,&uData,1,pOut,sizeof(wchar_t),NULL,NULL);
    return;
}    

void CChineseCode::Gb2312ToUnicode(wchar_t* pOut,char *gbBuffer)
{
    ::MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,gbBuffer,2,pOut,1);
    return ;
}

void CChineseCode::GB2312ToUTF_8(string& pOut,char *pText, int pLen)
{
    char buf[4];
    int nLength = pLen* 3;
    char* rst = new char[nLength];
   
    memset(buf,0,4);
    memset(rst,0,nLength);
   
    int i = 0;
    int j = 0;     
    while(i < pLen)
    {
            //如果是英文直接复制就可以
            if( *(pText + i) >= 0)
            {
                    rst[j++] = pText[i++];
            }
            else
            {
                    wchar_t pbuffer;
                    Gb2312ToUnicode(&pbuffer,pText+i);
                   
                    UnicodeToUTF_8(buf,&pbuffer);
                   
                    unsigned short int tmp = 0;
                    tmp = rst[j] = buf[0];
                    tmp = rst[j+1] = buf[1];
                    tmp = rst[j+2] = buf[2];   
                   
                    j += 3;
                    i += 2;
            }
    }
    rst[j] = '\0';

    //返回结果
    pOut = rst;            
    delete []rst;  
   
    return;
}

void CChineseCode::UTF_8ToGB2312(string &pOut, char *pText, int pLen)
{
    char * newBuf = new char[pLen];
    char Ctemp[4];
    memset(Ctemp,0,4);

    int i =0;
    int j = 0;
   
    while(i < pLen)
    {
        if(pText[i] > 0)
        {
                newBuf[j++] = pText[i++];                      
        }
        else                
        {
                WCHAR Wtemp;
                UTF_8ToUnicode(&Wtemp,pText + i);
       
                UnicodeToGB2312(Ctemp,Wtemp);
           
                newBuf[j] = Ctemp[0];
                newBuf[j + 1] = Ctemp[1];

                i += 3;   
                j += 2;  
        }
    }
    newBuf[j] = '\0';
   
    pOut = newBuf;
    delete []newBuf;
   
    return;
}