基于HTTP协议的网络应用程序

#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

#include <QNetworkAccessManager>

#include <QNetworkReply>

#include <QFile>

#include <QUrl>

#include <QDir>

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = nullptr);

    ~MainWindow();

private slots:

    void onFinished();          //网络响应结束

    void onReadyRead();         //读取下载的数据

    void onDownloadProgress(qint64 bytesRea, qint64 totalBytes);  //下载进程

    void on_pushButton_clicked();

    void on_pushButton_2_clicked();

private:

    Ui::MainWindow *ui;

    QNetworkAccessManager* m_networkManager;   //网络管理

    QNetworkReply* m_reply = nullptr; //网络响应

    QFile *m_file = nullptr;    //下载保存的临时文件

};

#endif // MAINWINDOW_H

#include "mainwindow.h"

#include "ui_mainwindow.h"

#include <QMessageBox>

#include <QDir>

#include <QDesktopServices>

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

    ui->progressBar->setValue(0);

    m_networkManager = new QNetworkAccessManager(this);

}

MainWindow::~MainWindow()

{

    delete ui;

}

//网络响应结束

void MainWindow::onFinished()

{

    QFileInfo fileInfo;

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

    m_file->close();

    delete m_file;

    m_file = nullptr;

    m_reply->deleteLater();

    m_reply = nullptr;

    if (ui->checkBox->isChecked())   //勾选了，下载完成之后，打开下载的文件               //absoluteFilePath() 返回包含文件名的绝对路径。

        QDesktopServices::openUrl(QUrl::fromLocalFile(fileInfo.absoluteFilePath()));  //使用默认软件的打开下载的文件

    ui->pushButton->setEnabled(true);

}

//读取下载的数据

void MainWindow::onReadyRead()

{

    m_file->write(m_reply->readAll());   //将返回的数据进行读取，写入到临时文件中

}

//下载进程

void MainWindow::onDownloadProgress(qint64 bytesRea, qint64 totalBytes)

{

    ui->progressBar->setMaximum(totalBytes);

    ui->progressBar->setValue(bytesRea);

}

void MainWindow::on_pushButton_clicked()

{

    QString urlSpec = ui->lineEdit->text().trimmed();  //去掉字符串的首尾的空格

    if (urlSpec.isEmpty()) {

        QMessageBox::information(this, "提示", "下载地址URL为NULL");

        return;

    }

    QUrl url = QUrl::fromUserInput(urlSpec);

    if (!url.isValid()) {

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

        return;

    }

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

    if (dir.isEmpty()) {

        QMessageBox::information(this, "提示", "保存地址为空");

        return;

    }

    QString fileFileName = dir + url.fileName(); //文件保存地址 + 文件名

    if (QFile::exists(fileFileName))

        QFile::remove(fileFileName);

    m_file = new QFile(fileFileName);    //创建临时文件

    if (!m_file->open(QIODevice::WriteOnly)) {

        QMessageBox::information(this, "提示", "打开临时文件错误");

        return;

    }

    ui->pushButton->setEnabled(false);

    m_reply = m_networkManager->get(QNetworkRequest(url));  //发送get网络请求，创建网络响应

    connect(m_reply, SIGNAL(finished()), this, SLOT(onFinished()));

    connect(m_reply, SIGNAL(readyRead()), this, SLOT(onReadyRead()));

    connect(m_reply, SIGNAL(downloadProgress(qint64,qint64)), this, SLOT(onDownloadProgress(qint64,qint64)));

}

void MainWindow::on_pushButton_2_clicked()

{

    QString currPath = QDir::currentPath();

    QDir dir(currPath);

    dir.mkdir("temp");

    ui->lineEdit_2->setText(currPath + "/temp/");

}