VC下CHttpFile.ReadString 中文读取乱码的编码方法

//UTF-8 to GB2312
CString WebProcess::Convert(CString str,int sourceCodepage, int targetCodepage){

	int len = str.GetLength();
	int unicodeLen = MultiByteToWideChar(sourceCodepage,0,str,-1,NULL,0);

	wchar_t *pUnicode;
	pUnicode = new wchar_t[unicodeLen+1];

	memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));
	MultiByteToWideChar(sourceCodepage,0,str,-1,(LPWSTR)pUnicode,unicodeLen);

	BYTE *pTargetData = NULL ;
	int targetLen = WideCharToMultiByte(targetCodepage,0,(LPWSTR)pUnicode,-1,(char*)pTargetData,0,NULL,NULL);

	pTargetData = new BYTE[targetLen+1];
	memset(pTargetData,0,targetLen+1);

	WideCharToMultiByte(targetCodepage,0,(LPWSTR)pUnicode,-1,(char*)pTargetData,targetLen,NULL,NULL);
	
	CString rt;
	rt.Format("%s",pTargetData);

	delete []pUnicode;
	delete []pTargetData;


	return rt ;

}