我不知道问题在哪里...编译器(Qt)在没有错误的情况下运行程序,但文件没有被下载...
请问您能告诉我出了什么问题吗?
我按照位于qt文件夹中的“下载”示例制作了自己的应用程序。唯一的区别是他们有控制台,而我有Windows应用程序。
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QtNetwork>
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_pushButton_clicked();
private:
Ui::MainWindow *ui;
};
class DownloadManager: public QObject
{
Q_OBJECT
QNetworkAccessManager manager;
QList<QNetworkReply *> currentDownloads;
public:
DownloadManager();
void doDownload(const QUrl &url);
QString saveFileName(const QUrl &url);
bool saveToDisk(const QString &filename, QIODevice *data);
public slots:
void execute();
void downloadFinished(QNetworkReply *reply);
};
#endif // MAINWINDOW_H
main.cpp
#include <QtGui/QApplication>
#include "mainwindow.h"
#include <QtNetwork>
#include <QNetworkAccessManager>
#include <QStringList>
#include <QCoreApplication>
#include <QFile>
#include <QFileInfo>
#include <QList>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QStringList>
#include <QTimer>
#include <QUrl>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
#if defined(Q_WS_S60)
w.showMaximized();
#else
w.show();
#endif
return a.exec();
}
DownloadManager::DownloadManager()
{
connect(&manager, SIGNAL(finished(QNetworkReply*)),
SLOT(downloadFinished(QNetworkReply*)));
}
void DownloadManager::doDownload(const QUrl &url)
{
QNetworkRequest request(url);
QNetworkReply *reply = manager.get(request);
currentDownloads.append(reply);
}
QString DownloadManager::saveFileName(const QUrl &url)
{
QString path = url.path();
QString basename = QFileInfo(path).fileName();
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;
}
bool DownloadManager::saveToDisk(const QString &filename, QIODevice *data)
{
QFile file(filename);
if (!file.open(QIODevice::WriteOnly)) {
fprintf(stderr, "Could not open %s for writing: %s\n",
qPrintable(filename),
qPrintable(file.errorString()));
return false;
}
file.write(data->readAll());
file.close();
return true;
}
void DownloadManager::execute()
{
QStringList args = QCoreApplication::instance()->arguments();
args[0]="http://www.google.ru/images/srpr/logo3w.png";
QString arg=args[0];
QUrl url = QUrl::fromEncoded(arg.toLocal8Bit());
doDownload(url);
}
void DownloadManager::downloadFinished(QNetworkReply *reply)
{
QUrl url = reply->url();
if (reply->error()) {
fprintf(stderr, "Download of %s failed: %s\n",
url.toEncoded().constData(),
qPrintable(reply->errorString()));
} else {
QString filename = saveFileName(url);
if (saveToDisk(filename, reply))
printf("Download of %s succeded (saved to %s)\n",
url.toEncoded().constData(), qPrintable(filename));
}
currentDownloads.removeAll(reply);
reply->deleteLater();
if (currentDownloads.isEmpty())
// all downloads finished
QCoreApplication::instance()->quit();
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
DownloadManager manager;
manager.execute();
QTimer::singleShot(0, &manager, SLOT(execute()));
}
fprintf
转换为消息框或其他GUI元素;它可能正在显示错误,但您无法看到它们,因为它是一个GUI应用程序而不是控制台应用程序。 - icktoofay