qt 5.15.2 网络文件下载功能

#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  fileUrlQUrl 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

#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

#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 overwriteint 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 outputprintf("Downloading %s...\n", url.toEncoded().constData());downloadTimer.start();
}void DownloadManager::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{progressBar.setStatus(bytesReceived, bytesTotal);// calculate the download speeddouble 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 failedfprintf(stderr, "Failed: %s\n", qPrintable(currentDownload->errorString()));output.remove();} else {// let's check if it was actually a redirectif (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

#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

#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 barint 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 barint center = (iteration % 48) + 1; // 50 spaces, minus 2QByteArray 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;
}