Qt Reference Documentation

# httpwindow.cpp Example File

network/http/httpwindow.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
     ** All rights reserved.
     ** Contact: Nokia Corporation (qt-info@nokia.com)
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
     **     the names of its contributors may be used to endorse or promote
     **     products derived from this software without specific prior written
     **     permission.
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     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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     ****************************************************************************/

     #include <QtGui>
     #include <QtNetwork>

     #include "httpwindow.h"
     #include "ui_authenticationdialog.h"

     HttpWindow::HttpWindow(QWidget *parent)
         : QDialog(parent)
     {
     #ifndef QT_NO_OPENSSL
         urlLineEdit = new QLineEdit("https://qt.nokia.com/");
     #else
         urlLineEdit = new QLineEdit("http://qt.nokia.com/");
     #endif

         urlLabel = new QLabel(tr("&URL:"));
         urlLabel->setBuddy(urlLineEdit);
         statusLabel = new QLabel(tr("Please enter the URL of a file you want to "
                                     "download."));

         downloadButton = new QPushButton(tr("Download"));
         downloadButton->setDefault(true);
         quitButton = new QPushButton(tr("Quit"));
         quitButton->setAutoDefault(false);

         buttonBox = new QDialogButtonBox;
         buttonBox->addButton(downloadButton, QDialogButtonBox::ActionRole);
         buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

         progressDialog = new QProgressDialog(this);

         connect(urlLineEdit, SIGNAL(textChanged(QString)),
                 this, SLOT(enableDownloadButton()));

         connect(&qnam, SIGNAL(authenticationRequired(QNetworkReply*,QAuthenticator*)),
                 this, SLOT(slotAuthenticationRequired(QNetworkReply*,QAuthenticator*)));
     #ifndef QT_NO_OPENSSL
         connect(&qnam, SIGNAL(sslErrors(QNetworkReply*,QList<QSslError>)),
                 this, SLOT(sslErrors(QNetworkReply*,QList<QSslError>)));
     #endif
         connect(progressDialog, SIGNAL(canceled()), this, SLOT(cancelDownload()));
         connect(downloadButton, SIGNAL(clicked()), this, SLOT(downloadFile()));
         connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));

         QHBoxLayout *topLayout = new QHBoxLayout;
         topLayout->addWidget(urlLabel);
         topLayout->addWidget(urlLineEdit);

         QVBoxLayout *mainLayout = new QVBoxLayout;
         mainLayout->addLayout(topLayout);
         mainLayout->addWidget(statusLabel);
         mainLayout->addWidget(buttonBox);
         setLayout(mainLayout);

         setWindowTitle(tr("HTTP"));
         urlLineEdit->setFocus();
     }

     void HttpWindow::startRequest(QUrl url)
     {
         reply = qnam.get(QNetworkRequest(url));
         connect(reply, SIGNAL(finished()),
                 this, SLOT(httpFinished()));
         connect(reply, SIGNAL(readyRead()),
                 this, SLOT(httpReadyRead()));
         connect(reply, SIGNAL(downloadProgress(qint64,qint64)),
                 this, SLOT(updateDataReadProgress(qint64,qint64)));
     }

     void HttpWindow::downloadFile()
     {
         url = urlLineEdit->text();

         QFileInfo fileInfo(url.path());
         QString fileName = fileInfo.fileName();
         if (fileName.isEmpty())
             fileName = "index.html";

         if (QFile::exists(fileName)) {
             if (QMessageBox::question(this, tr("HTTP"),
                                       tr("There already exists a file called %1 in "
                                          "the current directory. Overwrite?").arg(fileName),
                                       QMessageBox::Yes|QMessageBox::No, QMessageBox::No)
                 == QMessageBox::No)
                 return;
             QFile::remove(fileName);
         }

         file = new QFile(fileName);
         if (!file->open(QIODevice::WriteOnly)) {
             QMessageBox::information(this, tr("HTTP"),
                                      tr("Unable to save the file %1: %2.")
                                      .arg(fileName).arg(file->errorString()));
             delete file;
             file = 0;
             return;
         }

         progressDialog->setWindowTitle(tr("HTTP"));
         progressDialog->setLabelText(tr("Downloading %1.").arg(fileName));
         downloadButton->setEnabled(false);

         // schedule the request
         httpRequestAborted = false;
         startRequest(url);
     }

     void HttpWindow::cancelDownload()
     {
         statusLabel->setText(tr("Download canceled."));
         httpRequestAborted = true;
         reply->abort();
         downloadButton->setEnabled(true);
     }

     void HttpWindow::httpFinished()
     {
         if (httpRequestAborted) {
             if (file) {
                 file->close();
                 file->remove();
                 delete file;
                 file = 0;
             }
             reply->deleteLater();
             progressDialog->hide();
             return;
         }

         progressDialog->hide();
         file->flush();
         file->close();

         QVariant redirectionTarget = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
         if (reply->error()) {
             file->remove();
             QMessageBox::information(this, tr("HTTP"),
                                      tr("Download failed: %1.")
                                      .arg(reply->errorString()));
             downloadButton->setEnabled(true);
         } else if (!redirectionTarget.isNull()) {
             QUrl newUrl = url.resolved(redirectionTarget.toUrl());
             if (QMessageBox::question(this, tr("HTTP"),
                                       tr("Redirect to %1 ?").arg(newUrl.toString()),
                                       QMessageBox::Yes | QMessageBox::No) == QMessageBox::Yes) {
                 url = newUrl;
                 reply->deleteLater();
                 file->open(QIODevice::WriteOnly);
                 file->resize(0);
                 startRequest(url);
                 return;
             }
         } else {
             QString fileName = QFileInfo(QUrl(urlLineEdit->text()).path()).fileName();
             statusLabel->setText(tr("Downloaded %1 to current directory.").arg(fileName));
             downloadButton->setEnabled(true);
         }

         reply->deleteLater();
         reply = 0;
         delete file;
         file = 0;
     }

     void HttpWindow::httpReadyRead()
     {
         // this slot gets called every time the QNetworkReply has new data.
         // We read all of its new data and write it into the file.
         // That way we use less RAM than when reading it at the finished()
         // signal of the QNetworkReply
         if (file)
             file->write(reply->readAll());
     }

     void HttpWindow::updateDataReadProgress(qint64 bytesRead, qint64 totalBytes)
     {
         if (httpRequestAborted)
             return;

         progressDialog->setMaximum(totalBytes);
         progressDialog->setValue(bytesRead);
     }

     void HttpWindow::enableDownloadButton()
     {
         downloadButton->setEnabled(!urlLineEdit->text().isEmpty());
     }

     void HttpWindow::slotAuthenticationRequired(QNetworkReply*,QAuthenticator *authenticator)
     {
         QDialog dlg;
         Ui::Dialog ui;
         ui.setupUi(&dlg);
         dlg.adjustSize();
         ui.siteDescription->setText(tr("%1 at %2").arg(authenticator->realm()).arg(url.host()));

         // Did the URL have information? Fill the UI
         // This is only relevant if the URL-supplied credentials were wrong
         ui.userEdit->setText(url.userName());
         ui.passwordEdit->setText(url.password());

         if (dlg.exec() == QDialog::Accepted) {
             authenticator->setUser(ui.userEdit->text());
             authenticator->setPassword(ui.passwordEdit->text());
         }
     }

     #ifndef QT_NO_OPENSSL
     void HttpWindow::sslErrors(QNetworkReply*,const QList<QSslError> &errors)
     {
         QString errorString;
         foreach (const QSslError &error, errors) {
             if (!errorString.isEmpty())
                 errorString += ", ";
             errorString += error.errorString();
         }

         if (QMessageBox::warning(this, tr("HTTP"),
                                  tr("One or more SSL errors has occurred: %1").arg(errorString),
                                  QMessageBox::Ignore | QMessageBox::Abort) == QMessageBox::Ignore) {
             reply->ignoreSslErrors();
         }
     }
     #endif