UTF-8与GB2312之间的互换

相 信一定有不少的程序开发人员时常会遇到字符编码的问题，而这个问题也是非常让人头痛的。因为这些都是潜在的错误，要找出这些错误也得要有这方面的开发经验 才行。特别是在处理xml文档时 ，该问题的出现就更加的频繁了，有一次用java写服务器端程序，用vc写客户端与之交互。交互的协议都是用xml写的。结果在通讯时老是发现数据接受不 正确。纳闷！于是用抓取网络数据包工具抓取数据，后来才发现原来是java上xml的头是这样的,而vc上默认的是GB2312。所以一遇到汉字数据就不正确了。去网上找资料，这方面的文章好象特别少，针 对像这样的问题，下面我介绍一下我自己写的一个转换程序。当然，程序很简单。如果有画蛇添足的地方，还望各位高手一笑了之。
　　如果您对UTF- 8、Unicode、GB2312等还是很陌生的话，请查看 Unicode.html，我这里就不浪费口舌了。下面介绍一下WinAPI的两个函数：WideCharToMultiByte、 MultiByteToWideChar。

函数原型：

int WideCharToMultiByte(
 UINT CodePage, // code page
 DWORD dwFlags, // performance and mapping flags
 LPCWSTR lpWideCharStr, // wide-character string
 int cchWideChar, // number of chars in string
 LPSTR lpMultiByteStr, // buffer for new string
 int cbMultiByte, // size of buffer
 LPCSTR lpDefaultChar, // default for unmappable chars
 LPBOOL lpUsedDefaultChar // set when default char used
); //将宽字符转换成多个窄字符

int MultiByteToWideChar(
 UINT CodePage, // code page
 DWORD dwFlags, // character-type options
 LPCSTR lpMultiByteStr, // string to map
 int cbMultiByte, // number of bytes in string
 LPWSTR lpWideCharStr, // wide-character buffer
 int cchWideChar // size of buffer
);//将多个窄字符转换成宽字符      

需要用到的一些函数：

CString CXmlProcess::HexToBin(CString string)//将16进制数转换成2进制
{
 if( string == "0") return "0000";
 if( string == "1") return "0001";
 if( string == "2") return "0010";
 if( string == "3") return "0011";
 if( string == "4") return "0100";
 if( string == "5") return "0101";
 if( string == "6") return "0110";
 if( string == "7") return "0111";
 if( string == "8") return "1000";
 if( string == "9") return "1001";
 if( string == "a") return "1010";
 if( string == "b") return "1011";
 if( string == "c") return "1100";
 if( string == "d") return "1101";
 if( string == "e") return "1110";
 if( string == "f") return "1111";
 return "";
}


CString CXmlProcess::BinToHex(CString BinString)//将2进制数转换成16进制
{
 if( BinString == "0000") return "0";
 if( BinString == "0001") return "1";
 if( BinString == "0010") return "2";
 if( BinString == "0011") return "3";
 if( BinString == "0100") return "4";
 if( BinString == "0101") return "5";
 if( BinString == "0110") return "6";
 if( BinString == "0111") return "7";
 if( BinString == "1000") return "8";
 if( BinString == "1001") return "9";
 if( BinString == "1010") return "a";
 if( BinString == "1011") return "b";
 if( BinString == "1100") return "c";
 if( BinString == "1101") return "d";
 if( BinString == "1110") return "e";
 if( BinString == "1111") return "f";
 return "";
}

int CXmlProcess::BinToInt(CString string)//2进制字符数据转换成10进制整型
{
 int len =0;
 int tempInt = 0;
 int strInt = 0;
 for(int i =0 ;i < string.GetLength() ;i ++)
 {
         tempInt = 1;
         strInt = (int)string.GetAt(i)-48;
         for(int k =0 ;k < 7-i ; k++)
         {
   tempInt = 2*tempInt;
         }
         len += tempInt*strInt;
 }
 return len;
}      

　　UTF-8转换成GB2312先把UTF-8转换成Unicode.然后再把Unicode通过函数WideCharToMultiByte转换成GB2312

WCHAR* CXmlProcess::UTF_8ToUnicode(char *ustart)  //把UTF-8转换成Unicode
{
 char char_one;
 char char_two;
 char char_three;
 int Hchar;
 int Lchar;
 char uchar[2];
 WCHAR *unicode;
 CString string_one;
 CString string_two;
 CString string_three;
 CString combiString;
 char_one = *ustart;
 char_two = *(ustart+1);
 char_three = *(ustart+2);
 string_one.Format("%x",char_one);
 string_two.Format("%x",char_two);
 string_three.Format("%x",char_three);
 string_three = string_three.Right(2);
 string_two = string_two.Right(2);
 string_one = string_one.Right(2);
 string_three = HexToBin(string_three.Left(1))+HexToBin(string_three.Right(1));
 string_two = HexToBin(string_two.Left(1))+HexToBin(string_two.Right(1));
 string_one = HexToBin(string_one.Left(1))+HexToBin(string_one.Right(1));
 combiString = string_one +string_two +string_three;
 combiString = combiString.Right(20);
 combiString.Delete(4,2);
 combiString.Delete(10,2);
 Hchar = BinToInt(combiString.Left(8));
 Lchar = BinToInt(combiString.Right(8));
 uchar[1] = (char)Hchar;
 uchar[0] = (char)Lchar;
 unicode = (WCHAR *)uchar;
 return unicode;
}

char * CXmlProcess::UnicodeToGB2312(unsigned short uData)  //把Unicode 转换成 GB2312
{
 char *buffer ;
 buffer = new char[sizeof(WCHAR)];
 WideCharToMultiByte(CP_ACP,NULL,&uData,1,buffer,sizeof(WCHAR),NULL,NULL);
 return buffer;
}      

　　GB2312转换成UTF-8：先把GB2312通过函数MultiByteToWideChar转换成Unicode.然后再把Unicode通过拆开Unicode后拼装成UTF-8。

WCHAR * CXmlProcess::Gb2312ToUnicode(char *gbBuffer)  //GB2312 转换成　Unicode
{ 
 WCHAR *uniChar;
 uniChar = new WCHAR[1];
 ::MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,gbBuffer,2,uniChar,1);
 return uniChar;
}
char * CXmlProcess::UnicodeToUTF_8(WCHAR *UniChar) // Unicode 转换成UTF-8
{
 char *buffer;
 CString strOne;
 CString strTwo;
 CString strThree;
 CString strFour;
 CString strAnd;
 buffer = new char[3];
 int hInt,lInt;
 hInt = (int)((*UniChar)/256);
 lInt = (*UniChar)%256;
 CString string ;
 string.Format("%x",hInt);
 strTwo = HexToBin(string.Right(1));
 string = string.Left(string.GetLength() - 1);
 strOne = HexToBin(string.Right(1));
 string.Format("%x",lInt);
 strFour = HexToBin(string.Right(1));
 string = string.Left(string.GetLength() -1);
 strThree = HexToBin(string.Right(1));
 strAnd = strOne +strTwo + strThree + strFour;
 strAnd.Insert(0,"1110");
 strAnd.Insert(8,"10");
 strAnd.Insert(16,"10");
 strOne = strAnd.Left(8);
 strAnd = strAnd.Right(16);
 strTwo = strAnd.Left(8);
 strThree = strAnd.Right(8);
 *buffer = (char)BinToInt(strOne);
 buffer[1] = (char)BinToInt(strTwo);
 buffer[2] = (char)BinToInt(strThree);
 return buffer;
}     

例子：将GB2312转换成UTF-8的调用：

char * CXmlProcess::translateCharToUTF_8(char *xmlStream, int len) 
{
 int newCharLen =0 ;
 int oldCharLen = 0;
 int revCharLen = len;
 char* newCharBuffer;
 char* finalCharBuffer;
 char *buffer ;
 CString string;
 buffer  = new char[sizeof(WCHAR)];
 newCharBuffer = new char[int(1.5*revCharLen)];//设置最大的一个缓冲区
 while(oldCharLen < revCharLen)
 {
  if( *(xmlStream + oldCharLen) >= 0)
  {
   *(newCharBuffer+newCharLen) = *(xmlStream +oldCharLen);
   newCharLen ++;
   oldCharLen ++;
  }//如果是英文直接复制就可以
  else
  {
   WCHAR *pbuffer = this->Gb2312ToUnicode(xmlStream+oldCharLen);
   buffer = this->UnicodeToUTF_8(pbuffer);
   *(newCharBuffer+newCharLen) = *buffer;
   *(newCharBuffer +newCharLen +1) = *(buffer + 1);
   *(newCharBuffer +newCharLen +2) = *(buffer + 2);
   newCharLen += 3;
   oldCharLen += 2;
  }
 }
 newCharBuffer[newCharLen] = ''\0'';
 CString string1 ;
 string1.Format("%s",newCharBuffer);
 finalCharBuffer = new char[newCharLen+1];
 memcpy(finalCharBuffer,newCharBuffer,newCharLen+1);
 return finalCharBuffer;
}

例子：将UTF-8转换成GB2312的调用： 


char * CXmlProcess::TranslateUTF_8ToGB(char *xmlStream, int len)   //len 是xmlStream的长度 
{ 
    char * newCharBuffer = new char[len]; 
    int index =0; 
    int nCBIndex = 0; 
    while(index < len) 
    { 
        if(xmlStream[index] > 0)     // 如果是GB2312的字符 
        { 
            newCharBuffer[nCBIndex] = xmlStream[index];    //直接复制 
            index += 1;              //源字符串偏移量1 
            nCBIndex += 1;           //目标字符串偏移量1 
        } 
        else                 //如果是UTF-8的字符 
        { 
            WCHAR * Wtemp =  this->UTF_8ToUnicode(xmlStream + index);  //先把UTF-8转成Unicode 
            char * Ctemp  = this->UnicodeToGB2312(*Wtemp);//再把Unicode 转成 GB2312 
                    newCharBuffer[nCBIndex] = * Ctemp;         // 复制 
            newCharBuffer[nCBIndex + 1] = *(Ctemp + 1); 
            index += 3;     //源字符串偏移量3 
            nCBIndex += 2;   //目标字符串偏移量2  因为一个中文UTF-8占3个字节，GB2312占两个字节 
        } 
    } 
    newCharBuffer[nCBIndex] = 0; //结束符 
    return newCharBuffer;    
}