qt 5.15.2 网络文件下载功能

cpp 复制代码

#include <QCoreApplication>

#include <iostream>
#include <QFile>
#include <QTextStream>
//
#include <QtCore>
#include <QtNetwork>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QUrl>
#include <QDir>
//
#include <QStringList>
#include "downloadmanager.h"
//
int printf(QString line)
{
    std::cout<<line.toStdString()<<std::endl;
}
int printf(int line)
{
    std::cout<<line<<std::endl;
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    std::cout<<"Hello World! hsg77"<<std::endl;

    QString toDirPath="C:\\data\\obj\\test";

    DownloadManager manager;
    manager.setOutDir(toDirPath);
    //manager.append(arguments);

    //打开csv文件
    QFile file("E:\\QtProject\\objDownloadTest\\GridIdx_OBJ.csv");
    std::cout<<file.fileName().toStdString()<<std::endl;
    if(file.exists())
    {
        if(file.open(QIODevice::ReadOnly))
        {
            QTextStream in(&file);

            //std::cout<<"file state="<<in.atEnd()<<std::endl;

            while(!in.atEnd())
            {
                QString line=in.readLine();
                QStringList fds=line.split("	");

                //std::cout<<line.toStdString()<<std::endl;
                //printf(fds.length());

                //处理每一行的数据
                QString fileUrl=fds.at(13);
                printf("readydown="+fileUrl);                

                if(fileUrl!="FILE_URL")
                {
                    //下载文件  fileUrl
                    QUrl url(fileUrl);
                    manager.append(url);
                }
            }
            //
        }

    }
    //
    file.close();
    std::cout<<"csv file closed"<<std::endl;

    //开始下载开始
    QObject::connect(&manager,&DownloadManager::finished,&a,&QCoreApplication::quit);

    return a.exec();
}

定义：下载管理类

DownloadManager.h

cpp 复制代码

#ifndef DOWNLOADMANAGER_H
#define DOWNLOADMANAGER_H

#include <QtNetwork>
#include <QtCore>

#include "textprogressbar.h"

class DownloadManager: public QObject
{
    Q_OBJECT
public:
    explicit DownloadManager(QObject *parent = nullptr);

    void append(const QUrl &url);
    void append(const QStringList &urls);
    static QString saveFileName(const QUrl &url,const QString outDir);

    void setOutDir(const QString outDir);

signals:
    void finished();

private slots:
    void startNextDownload();
    void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
    void downloadFinished();
    void downloadReadyRead();

private:
    bool isHttpRedirect() const;
    void reportRedirect();

    QNetworkAccessManager manager;
    QQueue<QUrl> downloadQueue;
    QNetworkReply *currentDownload = nullptr;
    QFile output;
    QElapsedTimer downloadTimer;
    TextProgressBar progressBar;

    int downloadedCount = 0;
    int totalCount = 0;
    QString outDir="";
};

#endif // DOWNLOADMANAGER_H

DownloadManager.cpp

cpp 复制代码

#include "downloadmanager.h"

#include <QTextStream>

#include <cstdio>

using namespace std;

DownloadManager::DownloadManager(QObject *parent)
    : QObject(parent)
{
}

void DownloadManager::append(const QStringList &urls)
{
    for (const QString &urlAsString : urls)
        append(QUrl::fromEncoded(urlAsString.toLocal8Bit()));

    if (downloadQueue.isEmpty())
        QTimer::singleShot(0, this, &DownloadManager::finished);
}

void DownloadManager::append(const QUrl &url)
{
    if (downloadQueue.isEmpty())
        QTimer::singleShot(0, this, &DownloadManager::startNextDownload);

    downloadQueue.enqueue(url);
    ++totalCount;
}

QString DownloadManager::saveFileName(const QUrl &url,const QString outDir)
{
    QString path = url.path();
    QString basename = QFileInfo(path).fileName();

    QString newFilePath=outDir+"\\"+basename;
    return newFilePath;
    //
    if (basename.isEmpty())
        basename = "download";

    if (QFile::exists(basename)) {
        // already exists, don't overwrite
        int i = 0;
        basename += '.';
        while (QFile::exists(basename + QString::number(i)))
            ++i;

        basename += QString::number(i);
    }

    return basename;
}

void DownloadManager::setOutDir(const QString outDir)
{
    this->outDir=outDir;
}

void DownloadManager::startNextDownload()
{
    if (downloadQueue.isEmpty()) {
        printf("%d/%d files downloaded successfully\n", downloadedCount, totalCount);
        emit finished();
        return;
    }

    QUrl url = downloadQueue.dequeue();

    QString filename = saveFileName(url,this->outDir);
    output.setFileName(filename);
    if (!output.open(QIODevice::WriteOnly)) {
        fprintf(stderr, "Problem opening save file '%s' for download '%s': %s\n",
                qPrintable(filename), url.toEncoded().constData(),
                qPrintable(output.errorString()));

        startNextDownload();
        return;                 // skip this download
    }

    QNetworkRequest request(url);
    currentDownload = manager.get(request);
    connect(currentDownload, &QNetworkReply::downloadProgress,
            this, &DownloadManager::downloadProgress);
    connect(currentDownload, &QNetworkReply::finished,
            this, &DownloadManager::downloadFinished);
    connect(currentDownload, &QNetworkReply::readyRead,
            this, &DownloadManager::downloadReadyRead);

    // prepare the output
    printf("Downloading %s...\n", url.toEncoded().constData());
    downloadTimer.start();
}

void DownloadManager::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{
    progressBar.setStatus(bytesReceived, bytesTotal);

    // calculate the download speed
    double speed = bytesReceived * 1000.0 / downloadTimer.elapsed();
    QString unit;
    if (speed < 1024) {
        unit = "bytes/sec";
    } else if (speed < 1024*1024) {
        speed /= 1024;
        unit = "kB/s";
    } else {
        speed /= 1024*1024;
        unit = "MB/s";
    }

    progressBar.setMessage(QString::fromLatin1("%1 %2")
                               .arg(speed, 3, 'f', 1).arg(unit));
    progressBar.update();
}

void DownloadManager::downloadFinished()
{
    progressBar.clear();
    output.close();

    if (currentDownload->error()) {
        // download failed
        fprintf(stderr, "Failed: %s\n", qPrintable(currentDownload->errorString()));
        output.remove();
    } else {
        // let's check if it was actually a redirect
        if (isHttpRedirect()) {
            reportRedirect();
            output.remove();
        } else {
            printf("Succeeded.\n");
            ++downloadedCount;
        }
    }

    currentDownload->deleteLater();
    startNextDownload();
}

void DownloadManager::downloadReadyRead()
{
    output.write(currentDownload->readAll());
}

bool DownloadManager::isHttpRedirect() const
{
    int statusCode = currentDownload->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
    return statusCode == 301 || statusCode == 302 || statusCode == 303
           || statusCode == 305 || statusCode == 307 || statusCode == 308;
}

void DownloadManager::reportRedirect()
{
    int statusCode = currentDownload->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
    QUrl requestUrl = currentDownload->request().url();
    QTextStream(stderr) << "Request: " << requestUrl.toDisplayString()
                        << " was redirected with code: " << statusCode
                        << '\n';

    QVariant target = currentDownload->attribute(QNetworkRequest::RedirectionTargetAttribute);
    if (!target.isValid())
        return;
    QUrl redirectUrl = target.toUrl();
    if (redirectUrl.isRelative())
        redirectUrl = requestUrl.resolved(redirectUrl);
    QTextStream(stderr) << "Redirected to: " << redirectUrl.toDisplayString()
                        << '\n';
}

定义进度条类

TextProgressBar.h

cpp 复制代码

#ifndef TEXTPROGRESSBAR_H
#define TEXTPROGRESSBAR_H

#include <QString>

class TextProgressBar
{
public:
    void clear();
    void update();
    void setMessage(const QString &message);
    void setStatus(qint64 value, qint64 maximum);

private:
    QString message;
    qint64 value = 0;
    qint64 maximum = -1;
    int iteration = 0;
};

#endif // TEXTPROGRESSBAR_H

TextProgressBar.cpp

cpp 复制代码

#include "textprogressbar.h"

#include <QByteArray>

#include <cstdio>

using namespace std;

void TextProgressBar::clear()
{
    printf("\n");
    fflush(stdout);

    value = 0;
    maximum = -1;
    iteration = 0;
}

void TextProgressBar::update()
{
    ++iteration;

    if (maximum > 0) {
        // we know the maximum
        // draw a progress bar
        int percent = value * 100 / maximum;
        int hashes = percent / 2;

        QByteArray progressbar(hashes, '#');
        if (percent % 2)
            progressbar += '>';

        printf("\r[%-50s] %3d%% %s     ",
               progressbar.constData(),
               percent,
               qPrintable(message));
    } else {
        // we don't know the maximum, so we can't draw a progress bar
        int center = (iteration % 48) + 1; // 50 spaces, minus 2
        QByteArray before(qMax(center - 2, 0), ' ');
        QByteArray after(qMin(center + 2, 50), ' ');

        printf("\r[%s###%s]      %s      ",
               before.constData(), after.constData(), qPrintable(message));
    }
}

void TextProgressBar::setMessage(const QString &m)
{
    message = m;
}

void TextProgressBar::setStatus(qint64 val, qint64 max)
{
    value = val;
    maximum = max;
}

--the---end---

本blog地址：http://blog.csdn.net/hsg77