char *pStr = url_content.GetBuffer(url_content.GetLength());//取得str对象的原始字符串
int nBufferSize = MultiByteToWideChar(CP_UTF8,0,pStr,-1,NULL,0);//取得所需缓存的多少
wchar_t *pBuffer = (wchar_t*)malloc(nBufferSize * sizeof(wchar_t));//申请缓存空间
MuliByteToWideChar(CP_UFT8,0,pStr,-1,pBuffer,nBufferSize*sizeof(wchar_t));//转码
CString str = pBuffer；//转码后的值给字符串变量
free(pBuffer);//释放缓存