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Accepted
Alrott SlimRG
Asked:2022-01-02 02:13:27 +0000 UTC2022-01-02 02:13:27 +0000 UTC

如何基于 QNetworkAccessManager 进行互联网存在检查或出了什么问题？

  • 772

有一个代码：

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    // Check internet connection
    QNetworkAccessManager nam;
    QNetworkRequest req(QUrl("https://translate.yandex.ru"));
    QNetworkReply *reply = nam.get(req);
    QEventLoop loop;
    QObject::connect(reply, SIGNAL(readyRead()), &loop, SLOT(quit()));
    QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    if(!reply->isFinished())
    loop.exec();
    if(reply->bytesAvailable())
    qDebug() << "You are connected to the internet :)"; else qDebug() << "You are not connected to the internet :(";
}

抛出一个错误：

D:\DWAKU2\DWAKU2\mainwindow.cpp:37: 错误：没有匹配的成员函数调用“连接”

屏幕： 在此处输入图像描述

头文件代码：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QDebug>
#include <QNetworkAccessManager>
#include <QObject>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void SettingsLabelPressed();

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

PRO文件代码：

QT       += core gui
QT       += network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    bglabelclass.cpp \
    closelabelclass.cpp \
    main.cpp \
    mainwindow.cpp \
    settingslabelclass.cpp

HEADERS += \
    bglabelclass.hpp \
    closelabelclass.hpp \
    mainwindow.h \
    settingslabelclass.hpp

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
    res.qrc

DISTFILES += \
    bg.svg \
    pictures/svg/dynamic/close/main.svg \
    pictures/svg/dynamic/close/on_click.svg \
    pictures/svg/dynamic/close/on_enter.svg \
    pictures/svg/dynamic/loading/3.svg \
    pictures/svg/dynamic/loading/4.svg \
    pictures/svg/dynamic/loading/5.svg \
    pictures/svg/dynamic/loading/6.svg \
    pictures/svg/dynamic/loading/loader.svg \
    pictures/svg/dynamic/loading/main.gif \
    pictures/svg/dynamic/loading/on_click.svg \
    pictures/svg/dynamic/loading/on_enter.svg \
    pictures/svg/dynamic/settings/main.svg \
    pictures/svg/dynamic/settings/on_click.svg \
    pictures/svg/dynamic/settings/on_enter.svg \
    pictures/svg/main/bg.svg \
    pictures/svg/main/logo.svg

Qt版本：5.12.2 MinGW x64

错误是什么或如何正确检查对站点的访问？

c++

1 个回答

  1. Best Answer
    1. 检查一切是否已连接
    #include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
    1. QNetworkReply 没有完成信号。这是一个 QNetworkAccessManager 信号。另外，它有不同的签名
    2. 检查错误代码可能会更好。
        QNetworkAccessManager nam;
    QNetworkRequest req(QUrl("https://translate.yandex.ru"));
    QNetworkReply *reply = nam.get(req);
    QEventLoop loop;
    QObject::connect(reply, SIGNAL(readyRead()), &loop, SLOT(quit()));
    QObject::connect(&nam, SIGNAL(finished(QNetworkReply*)), &loop, SLOT(quit()));
    if(!reply->isFinished())
    loop.exec();
    if(reply->error()==QNetworkReply::NoError)
    qDebug() << "You are connected to the internet :)"; else qDebug() << "You have an net error:"<<reply->errorString();
    • 1

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