httpwindow.cpp Example File
^{network/http/httpwindow.cpp}

    /****************************************************************************
    **
    ** Copyright (C) 2004-2006 Trolltech ASA. All rights reserved.
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
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    ** review the following information:
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    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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    #include <QtGui>
    #include <QtNetwork>

    #include "httpwindow.h"

    HttpWindow::HttpWindow(QWidget *parent)
        : QDialog(parent)
    {
        urlLineEdit = new QLineEdit("http://www.ietf.org/iesg/1rfc_index.txt");

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

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

        progressDialog = new QProgressDialog(this);

        http = new QHttp(this);

        connect(urlLineEdit, SIGNAL(textChanged(const QString &)),
                this, SLOT(enableDownloadButton()));
        connect(http, SIGNAL(requestFinished(int, bool)),
                this, SLOT(httpRequestFinished(int, bool)));
        connect(http, SIGNAL(dataReadProgress(int, int)),
                this, SLOT(updateDataReadProgress(int, int)));
        connect(http, SIGNAL(responseHeaderReceived(const QHttpResponseHeader &)),
                this, SLOT(readResponseHeader(const QHttpResponseHeader &)));
        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);

        QHBoxLayout *buttonLayout = new QHBoxLayout;
        buttonLayout->addStretch(1);
        buttonLayout->addWidget(downloadButton);
        buttonLayout->addWidget(quitButton);

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

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

    void HttpWindow::downloadFile()
    {
        QUrl url(urlLineEdit->text());
        QFileInfo fileInfo(url.path());
        QString fileName = fileInfo.fileName();

        if (QFile::exists(fileName)) {
            QMessageBox::information(this, tr("HTTP"),
                                     tr("There already exists a file called %1 in "
                                        "the current directory.")
                                     .arg(fileName));
            return;
        }

        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;
        }

        http->setHost(url.host(), url.port() != -1 ? url.port() : 80);
        if (!url.userName().isEmpty())
            http->setUser(url.userName(), url.password());

        httpRequestAborted = false;
        httpGetId = http->get(url.path(), file);

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

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

    void HttpWindow::httpRequestFinished(int requestId, bool error)
    {
        if (httpRequestAborted) {
            if (file) {
                file->close();
                file->remove();
                delete file;
                file = 0;
            }

            progressDialog->hide();
            return;
        }

        if (requestId != httpGetId)
            return;

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

        if (error) {
            file->remove();
            QMessageBox::information(this, tr("HTTP"),
                                     tr("Download failed: %1.")
                                     .arg(http->errorString()));
        } else {
            QString fileName = QFileInfo(QUrl(urlLineEdit->text()).path()).fileName();
            statusLabel->setText(tr("Downloaded %1 to current directory.").arg(fileName));
        }

        downloadButton->setEnabled(true);
        delete file;
        file = 0;
    }

    void HttpWindow::readResponseHeader(const QHttpResponseHeader &responseHeader)
    {
        if (responseHeader.statusCode() != 200) {
            QMessageBox::information(this, tr("HTTP"),
                                     tr("Download failed: %1.")
                                     .arg(responseHeader.reasonPhrase()));
            httpRequestAborted = true;
            progressDialog->hide();
            http->abort();
            return;
        }
    }

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

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

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