• #QT（网络文件下载）

    1.IDE：QTCreator

    2.实验：从网络上下载devc++

    链接：http://crxzc.198424.com/dev-cpp_5.11_setup.zip

    3.记录：

    （1）主界面

    （2）check box

     

    （3）缺省路径的实现

    1. void Widget::on_defaultpath_pb_clicked()     //缺省路径按钮按下时
    2. {
    3.    QString path="c:/Users/***/Desktop/music_path/";       // '/'后面接文件的名字，即为存放在music_path路径下面的文件
    4.    ui->keeppath_text->setText(path);
    5. }

    （4）下载进度加载实现

    1. void Widget::DownLoad_Progress(qint64 byteNow,qint64 byteTotal)  //下载进度
    2. {
    3.     ui->downloadprogress_bar->setMaximum(byteTotal);
    4.     ui->downloadprogress_bar->setValue(byteNow);
    5. }

    （5）下载的实现

    1. void Widget::Network_ReadyToDownload() //准备下载
    2. {
    3.     downloadfile->write(networkreply->readAll());   //把所有得到的响应数据写入downloadfile里面
    4. }

    （6）网络回应的实现

    1. void Widget::Network_Reply()        //网络回应
    2. {
    3.     QFileInfo fileinfo;
    4.     fileinfo.setFile(downloadfile->fileName());
    5.     downloadfile->close();
    6.     delete downloadfile;
    7.     downloadfile=Q_NULLPTR;
    8.     networkreply->deleteLater();
    9.     networkreply=Q_NULLPTR;
    10.     if(ui->openafterdownload_check->isChecked()){     //下载完成后打开勾选
    11.         QDesktopServices::openUrl(QUrl::fromLocalFile(fileinfo.absolutePath()));
    12.         ui->download_pb->setEnabled(true);
    13.     }
    14.  
    15. }

     （7）下载按钮按下时进行

    1. void Widget::on_download_pb_clicked()      //下载按钮按下时
    2. {
    3.     QString url_text=ui->url_text->text().trimmed();   //trimmed可以去掉空格
    4.     if(url_text.isEmpty())                            //先检验是否输入
    5.         QMessageBox::information(this,"empty!","请输入网址");
    6.  
    7.     QUrl url=QUrl::fromUserInput(url_text);
    8.     if(!url.isValid())      //检查网址是否无效
    9.       {
    10.         QMessageBox::information(this,"invalid url!",QString("无效的网址%1\n错误信息%2").arg(url_text,url.errorString()));  //打印错误信息
    11.         return;
    12.       }
    13.  
    14.     if(ui->keeppath_text->text().isEmpty())    //检查保存路径是否为空
    15.       {
    16.          QMessageBox::information(this,"路径错误","请输入路径");
    17.          return;
    18.       }
    19.  
    20.     QString keep_path=ui->keeppath_text->text().trimmed()+url.fileName();   //传入路径（组合）
    21.  
    22.       if(QFile::exists(keep_path))                 //判断路径是否存在
    23.         QFile::remove(keep_path);
    24.  
    25.         downloadfile=new QFile(keep_path);
    26.  
    27.       if(!downloadfile->open(QIODevice::WriteOnly)){
    28.         QMessageBox::information(this,"出错了","临时文件打开失败");
    29.           return;
    30.     }
    31.  
    32.       ui->download_pb->setDisabled(true);   //禁止再次点击下载（下载中）
    33.       networkreply=networkaccessmanager.get(QNetworkRequest(url));   //获取网络请求回应
    34.       connect(networkreply,SIGNAL(finished()),this,SLOT(Network_Reply()));   //获得网络回应
    35.       connect(networkreply,SIGNAL(readyRead()),this,SLOT(Network_ReadyToDownload()));  //准备下载
    36.       connect(networkreply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(DownLoad_Progress(qint64,qint64)));  //下载进度
    37.  
    38. }

    4.代码

    pro

    1. QT       += core gui network
    2.  
    3. greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
    4.  
    5. CONFIG += c++17
    6.  
    7. # You can make your code fail to compile if it uses deprecated APIs.
    8. # In order to do so, uncomment the following line.
    9. #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
    10.  
    11. SOURCES += \
    12.     main.cpp \
    13.     widget.cpp
    14.  
    15. HEADERS += \
    16.     widget.h
    17.  
    18. FORMS += \
    19.     widget.ui
    20.  
    21. # Default rules for deployment.
    22. qnx: target.path = /tmp/$${TARGET}/bin
    23. else: unix:!android: target.path = /opt/$${TARGET}/bin
    24. !isEmpty(target.path): INSTALLS += target

    widget.cpp

    1. #include "widget.h"
    2. #include "ui_widget.h"
    3. #include 
    4. #include 
    5. #include 
    6. #include 
    7. #include 
    8. Widget::Widget(QWidget *parent)
    9.     : QWidget(parent)
    10.     , ui(new Ui::Widget)
    11. {
    12.     ui->setupUi(this);
    13. }
    14.  
    15. Widget::~Widget()
    16. {
    17.     delete ui;
    18. }
    19.  
    20. void Widget::Network_Reply()        //网络回应
    21. {
    22.     QFileInfo fileinfo;
    23.     fileinfo.setFile(downloadfile->fileName());
    24.     downloadfile->close();
    25.     delete downloadfile;
    26.     downloadfile=Q_NULLPTR;
    27.     networkreply->deleteLater();
    28.     networkreply=Q_NULLPTR;
    29.     if(ui->openafterdownload_check->isChecked()){     //下载完成后打开勾选
    30.         QDesktopServices::openUrl(QUrl::fromLocalFile(fileinfo.absolutePath()));
    31.         ui->download_pb->setEnabled(true);
    32.     }
    33.  
    34. }
    35. void Widget::Network_ReadyToDownload() //准备下载
    36. {
    37.     downloadfile->write(networkreply->readAll());   //把所有得到的响应数据写入downloadfile里面
    38. }
    39. void Widget::DownLoad_Progress(qint64 byteNow,qint64 byteTotal)  //下载进度
    40. {
    41.     ui->downloadprogress_bar->setMaximum(byteTotal);
    42.     ui->downloadprogress_bar->setValue(byteNow);
    43. }
    44.  
    45. void Widget::on_defaultpath_pb_clicked()     //缺省路径按钮按下时
    46. {
    47.    QString path="c:/Users/***/Desktop/music_path/";       // '/'后面接文件的名字，即为存放在music_path路径下面的文件
    48.    ui->keeppath_text->setText(path);
    49. }
    50.  
    51.  
    52. void Widget::on_download_pb_clicked()      //下载按钮按下时
    53. {
    54.     QString url_text=ui->url_text->text().trimmed();   //trimmed可以去掉空格
    55.     if(url_text.isEmpty())                            //先检验是否输入
    56.         QMessageBox::information(this,"empty!","请输入网址");
    57.  
    58.     QUrl url=QUrl::fromUserInput(url_text);
    59.     if(!url.isValid())      //检查网址是否无效
    60.       {
    61.         QMessageBox::information(this,"invalid url!",QString("无效的网址%1\n错误信息%2").arg(url_text,url.errorString()));  //打印错误信息
    62.         return;
    63.       }
    64.  
    65.     if(ui->keeppath_text->text().isEmpty())    //检查保存路径是否为空
    66.       {
    67.          QMessageBox::information(this,"路径错误","请输入路径");
    68.          return;
    69.       }
    70.  
    71.     QString keep_path=ui->keeppath_text->text().trimmed()+url.fileName();   //传入路径（组合）
    72.  
    73.       if(QFile::exists(keep_path))                 //判断路径是否存在
    74.         QFile::remove(keep_path);
    75.  
    76.         downloadfile=new QFile(keep_path);
    77.  
    78.       if(!downloadfile->open(QIODevice::WriteOnly)){
    79.         QMessageBox::information(this,"出错了","临时文件打开失败");
    80.           return;
    81.     }
    82.  
    83.       ui->download_pb->setDisabled(true);   //禁止再次点击下载（下载中）
    84.       networkreply=networkaccessmanager.get(QNetworkRequest(url));   //获取网络请求回应
    85.       connect(networkreply,SIGNAL(finished()),this,SLOT(Network_Reply()));   //获得网络回应
    86.       connect(networkreply,SIGNAL(readyRead()),this,SLOT(Network_ReadyToDownload()));  //准备下载
    87.       connect(networkreply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(DownLoad_Progress(qint64,qint64)));  //下载进度，注意信号是QT自带的函数，而槽是自己定义在头文件的
    88.  
    89. }
    90.

    widget.h

    1. #ifndef WIDGET_H
    2. #define WIDGET_H
    3.  
    4. #include 
    5.  
    6. #include 
    7. #include 
    8. #include 
    9. #include 
    10. QT_BEGIN_NAMESPACE
    11. namespace Ui {
    12. class Widget;
    13. }
    14. QT_END_NAMESPACE
    15.  
    16. class Widget : public QWidget
    17. {
    18.     Q_OBJECT
    19. private:                         //
    20.     QNetworkAccessManager networkaccessmanager;
    21.     QNetworkReply *networkreply;
    22.     QFile *downloadfile;
    23. private slots:
    24.     void Network_Reply();        //网络回应
    25.     void Network_ReadyToDownload(); //准备下载
    26.     void DownLoad_Progress(qint64 byteNow,qint64 byteTotal);  //下载进度
    27.     void on_defaultpath_pb_clicked();
    28.  
    29.     void on_download_pb_clicked();
    30.  
    31. public:
    32.     Widget(QWidget *parent = nullptr);
    33.     ~Widget();
    34.  
    35. private:
    36.     Ui::Widget *ui;
    37. };
    38. #endif // WIDGET_H

     

     

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  • 原文地址：https://blog.csdn.net/byhyf83862547/article/details/136625724