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一、创建界面文件

LCDnumber

二、创建mythread类，继承QObject

三、在MyThread.h文件做修改，并且加上函数声明

引入头文件，改变继承

#ifndef MYTHREAD_H
#define MYTHREAD_H#include <QThread>class MyThread : public QThread
{Q_OBJECT
public:explicit MyThread(QObject *parent = 0);protected:void run(); // 入口函数 -- 需要start()启动signals:void sigDone();public slots:
};#endif // MYTHREAD_H

四、实现run方法

#include "mythread.h"MyThread::MyThread(QObject *parent) : QThread(parent)
{}void MyThread::run()
{// 模拟复杂的操作sleep(5); //休眠5semit sigDone();
}

五、使用计时器来控制LCDnumber

//计时器mytimer = new QTimer(this);myt = new MyThread(this);connect(mytimer, &QTimer::timeout, this, [=](){static int num = 0;ui->lcdNumber->display(num++);});

六、实现按钮的槽函数

void MyWidget::on_begin_clicked()
{//如果计时器开着if(mytimer->isActive() == true){return;}// 启动定时器mytimer->start(1000); // ms// 启动子线程myt->start();
}

子线程运行结束后，停止计数器

// 子线程信号，子线程运行结束停止计数器
    connect(myt, &MyThread::finished, mytimer, &QTimer::stop); 

完整代码

mythread.cpp

#include "mythread.h"MyThread::MyThread(QObject *parent) : QThread(parent)
{}void MyThread::run()
{// 模拟复杂的操作sleep(5); //休眠5semit sigDone();
}

mythread.h

#ifndef MYTHREAD_H
#define MYTHREAD_H#include <QThread>class MyThread : public QThread
{Q_OBJECT
public:explicit MyThread(QObject *parent = 0);protected:void run(); // 入口函数 -- 需要start()启动signals:void sigDone();public slots:
};#endif // MYTHREAD_H

mywidget.cpp

#include "mywidget.h"
#include "ui_mywidget.h"
#include <QThread>
#include <QDebug>MyWidget::MyWidget(QWidget *parent) :QWidget(parent),ui(new Ui::MyWidget)
{ui->setupUi(this);//计时器mytimer = new QTimer(this);myt = new MyThread(this);connect(mytimer, &QTimer::timeout, this, [=](){static int num = 0;ui->lcdNumber->display(num++);});// 子线程信号，子线程运行结束停止计数器connect(myt, &MyThread::finished, mytimer, &QTimer::stop);}MyWidget::~MyWidget()
{delete ui;
}void MyWidget::on_begin_clicked()
{//如果计时器开着if(mytimer->isActive() == true){return;}// 启动定时器mytimer->start(1000); // ms// 启动子线程myt->start();
}

mywidget.h

#ifndef MYWIDGET_H
#define MYWIDGET_H#include <QWidget>
#include <QTimer>
#include "mythread.h"namespace Ui {
class MyWidget;
}class MyWidget : public QWidget
{Q_OBJECTpublic:explicit MyWidget(QWidget *parent = 0);~MyWidget();private slots:void on_begin_clicked();private:Ui::MyWidget *ui;QTimer* mytimer;MyThread *myt;
};#endif // MYWIDGET_H