#include <QtCore>

 #include <QNetworkReply>

 #include <QNetworkAccessManager>

 int main(int argc, char *argv[])

 {

     QCoreApplication app(argc, argv);

     QUrl url("http://sw.bos.baidu.com/sw-search-sp/software/d4e97ccd4bd9f/jdk-8u144-windows-i586_8.0.1440.1.exe");

     auto request = QNetworkRequest(url);

     //request.setRawHeader("Host", "www.baidu.com");

     request.setRawHeader("User-Agent", "curl/7.55.1");

     //request.setRawHeader("Accept", "*/*");

     //request.setRawHeader("Connection", "keep-alive");

     request.setRawHeader("Accept-Encoding", "*");

     //qDebug() << request.rawHeaderList();

     auto manager = new QNetworkAccessManager;

     manager->head(request);

     QEventLoop loop;

     QObject::connect(manager, &QNetworkAccessManager::finished, &loop,

         [&](QNetworkReply* reply) {

         qDebug() << reply->rawHeaderList();

         qDebug() << reply->header(QNetworkRequest::ContentLengthHeader).toInt();

         for (auto ele : reply->rawHeaderPairs()) qDebug() << ele.first << ":" << ele.second;

         reply->deleteLater();

         loop.exit();

     });

     loop.exec();

     return ;

 }

("Server", "Date", "Content-Type", "Content-Length", "Connection", "ETag", "Last-Modified", "Expires", "Age", "Accept-Ranges", "Content-MD5", "x-bce-debug-id", "x-bce-request-id", "Ohc-Response-Time")

"Server" : "JSP3/2.0.14"

"Date" : "Fri, 13 Oct 2017 07:01:18 GMT"

"Content-Type" : "application/octet-stream"

"Content-Length" : ""

"Connection" : "close"

"ETag" : "\"8f189a37b323d81c0f0e013cf3070c93\""

"Last-Modified" : "Thu, 27 Jul 2017 07:09:28 GMT"

"Expires" : "Fri, 13 Oct 2017 07:40:11 GMT"

"Age" : ""

"Accept-Ranges" : "bytes"

"Content-MD5" : "jxiaN7Mj2BwPDgE88wcMkw=="

"x-bce-debug-id" : "MTAuMTk0LjIzNC40ODpUaHUsIDI3IEp1bCAyMDE3IDE1OjE5OjU2IENTVDoxMTk2OTEwMzI0"

"x-bce-request-id" : "9e484498-6dbd-4a98-9bf7-39cb5f47ff7c"

"Ohc-Response-Time" : "1 0 0 0 0 0"

Press any key to continue . . .

 QString WebRequest(QString url, int& status_code, QString method,

         QByteArray postData,QList<QNetworkReply::RawHeaderPair>* reply_pairs, int time_out)

 {

     QNetworkAccessManager networkManager;

     QNetworkRequest request;

     request.setUrl(QUrl(url));

     request.setHeader(QNetworkRequest::UserAgentHeader,

         UserAgent);

     request.setRawHeader("Accept","*/*");

     request.setRawHeader("Accept-Encoding", "*");

     QNetworkReply* reply;

     if(method == "get")

     {

         reply = networkManager.get(request);

     }

     else if(method == "post")

     {

         request.setHeader(QNetworkRequest::ContentTypeHeader,

             "application/x-www-form-urlencoded");

         reply = networkManager.post(request, postData);

     }

     else

     {

         qDebug() << "method not support.";

         return QString("");

     }

     QTimer timer;

     timer.setSingleShot(true);

     QEventLoop loop;

     QObject::connect(&timer, SIGNAL(timeout()), &loop, SLOT(quit()));

     QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));

     if (time_out <= )

     {

         time_out = ;

     }

     timer.start(time_out);   // 3 secs. timeout

     loop.exec();

     if (timer.isActive()) {

         timer.stop();

         if (reply->error() > ) {

             qDebug() << "error";// handle error

         }

         else {

             status_code = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();

             if (status_code >=  && status_code < )

             {

                 // Success

                 if (reply_pairs)

                 {

                     *reply_pairs = reply->rawHeaderPairs();

                 }

                 return QString(reply->readAll());

             }

         }

     }

     else {

         // timeout

         QObject::disconnect(reply, SIGNAL(finished()), &loop, SLOT(quit()));

         reply->abort();

         return QString("");

     }

 }