#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

#include <QNetworkAccessManager>

#include <QNetworkReply>

#include <QFile>

#include <QDir>

#include <QMessageBox>

#include <QDesktopServices>

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = nullptr);

    ~MainWindow();

private:

    QNetworkAccessManager networkManager; //网络管理

    QNetworkReply *reply; //网络响应

    QFile *downloadedFile; //下载保存的临时文件

private slots:

    void on_finished();

    void on_readyRead();

    void on_downloadProgress(qint64 bytesRead ,qint64 totalBytes);

    void on_pushButton_2_clicked();

    void on_pushButton_clicked();

private:

    Ui::MainWindow *ui;

};

#endif // MAINWINDOW_H

#include "mainwindow.h"

#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

    ui->progressBar->setValue(0);

}

MainWindow::~MainWindow()

{

    delete ui;

}

void MainWindow::on_finished()

{

    QFileInfo fileInfo;

    fileInfo.setFile(downloadedFile->fileName());

    downloadedFile->close();

    delete downloadedFile;

    downloadedFile = Q_NULLPTR;

    reply->deleteLater();

    reply = Q_NULLPTR;

    if(ui->checkBox->isChecked())

    {

       QDesktopServices::openUrl(QUrl::fromLocalFile(fileInfo.absoluteFilePath()));

       ui->pushButton->setEnabled(true);

    }

}

void MainWindow::on_readyRead()

{

    downloadedFile->write(reply->readAll());

}

void MainWindow::on_downloadProgress(qint64 bytesRead, qint64 totalBytes)

{

    ui->progressBar->setMaximum(totalBytes);

    ui->progressBar->setValue(bytesRead);

}

void MainWindow::on_pushButton_2_clicked()

{

    //缺省路径

    QString curPath = QDir::currentPath();

    QDir dir(curPath);

    QString sub = "temp";

    dir.mkdir(sub);

    ui->lineEdit_2->setText(curPath+"/"+sub+"/");

}

void MainWindow::on_pushButton_clicked()

{

    //下载

    QString urlSpec =ui->lineEdit->text().trimmed();

    if(urlSpec.isEmpty())

    {

        QMessageBox::information(this,"错误","请指定需要下载的URL");

        return;

    }

    QUrl newurl = QUrl::fromUserInput(urlSpec);

    if(!newurl.isValid())

    {

        QMessageBox::information(this,"错误",QString("无效URL：%1\n错误信息：%2").arg(urlSpec,newurl.errorString()));

        return;

    }

    QString tempDir = ui->lineEdit_2->text().trimmed();

    if(tempDir.isEmpty())

    {

        QMessageBox::information(this,"错误","请指定保存下载文件的路径");

        return;

    }

    QString fullFileName = tempDir +newurl.fileName();

    if(QFile::exists(fullFileName))

    {

        QFile::remove(fullFileName);

    }

    downloadedFile = new QFile(fullFileName);

    if(!downloadedFile->open(QIODevice::WriteOnly))

    {

        QMessageBox::information(this,"错误","临时文件打开错误");

        return;

    }

    ui->pushButton->setEnabled(false);

    reply = networkManager.get(QNetworkRequest(newurl));

    connect(reply,SIGNAL(finished()),this,SLOT(on_finished()));

    connect(reply,SIGNAL(readyRead()),this,SLOT(on_readyRead()));

    connect(reply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(on_downloadProgress(qint64,qint64)));

}