定时获取时间

#-------------------------------------------------
#
# Project created by QtCreator 2020-05-03T00:50:41
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = time
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += 
        main.cpp 
        gettime.cpp

HEADERS += 
        gettime.h

FORMS += 
        gettime.ui

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

gettime.h

#ifndef GETTIME_H
#define GETTIME_H

#include <QMainWindow>
#include <QLabel>
#include <QTime>
#include <QString>
#include <QTimer>

namespace Ui {
class getTime;
}

class getTime : public QMainWindow
{
    Q_OBJECT
public:
    explicit getTime(QWidget *parent = nullptr);
    ~getTime();
public slots:
    void setValue();
private:
    Ui::getTime *ui;
    QTimer* timer;
};

#endif // GETTIME_H

gettime.cpp

#include "gettime.h"
#include "ui_gettime.h"

getTime::getTime(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::getTime)
{
    ui->setupUi(this);
    timer = new QTimer();
    connect(timer, SIGNAL(timeout()), this, SLOT(setValue()));
    timer->start(200);
}

getTime::~getTime()
{
    if(timer)
    {
        timer->stop();
        delete timer;
    }
    delete ui;
}

void getTime::setValue()
{
    QString str = QTime::currentTime().toString("hh:mm:ss");
    ui->pLabel->setText(str);
}

main.cpp

#include "gettime.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    getTime w;
    w.show();

    return a.exec();
}