利用curl计算网络文件大小

double zipsize = 0;
CURL *handle = curl_easy_init();
curl_easy_setopt(handle, CURLOPT_URL, url);
curl_easy_setopt(handle, CURLOPT_HEADER, 1);   //只需要header头
curl_easy_setopt(handle, CURLOPT_NOBODY, 1);   //不需要body

if (curl_easy_perform(handle) == CURLE_OK)
{
curl_easy_getinfo(handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &zipsize);
packageBytesTotal = (int)((zipsize / 1000) + 0.5);
std::cout << "当前要加载的包大小为: " << packageBytesTotal << "KB" << std::endl;
}
curl_easy_cleanup(handle);