Qt5网络请求使用及WebRequest函数

Qt5模拟curl进行HTTP的head请求， curl -I <url> ：

 #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 ;
 }

输出结果：

("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 . . .

封装成 WebRequest 函数：

 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("");
     }
 }