QT的多线程编程有两种

1、自定义类继承QThread

第一种是自定义一个类继承于QThread，重写run()方法来实现。然后当需要使用线程的时候你就新建一个自定义对象，然后调用start方法开始运行。

下面的例子是widget里面创建一个线程，然后调用start开始运行，线程运行run方法发送信号，widget接收到信号打印。

#include "mythread.h"

myThread::myThread(QThread *parent)
    : QThread{parent}
{

}

void myThread::run()
{
    emit showSignal();
}

#ifndef MYTHREAD_H
#define MYTHREAD_H

#include <QThread>

class myThread : public QThread
{
    Q_OBJECT
public:
    explicit myThread(QThread *parent = nullptr);
    void run() override;

signals:
    void showSignal();

};

#endif // MYTHREAD_H

#include "widget.h"
#include "ui_widget.h"
#include "mythread.h"

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

    myThread *thread=new myThread();
    connect(thread,&myThread::showSignal,[=](){
        qDebug() << "mythread is running";
    });

    thread->start();
}

Widget::~Widget()
{
    delete ui;
}

2、moveToThread()方法

这种方法是 自定义一个工作类，然后让这个工作类在线程里面运行，而他和主线程的通信方法，通过信号与槽来实现。

#ifndef WORKER_H
#define WORKER_H

#include <QObject>

class worker : public QObject
{
    Q_OBJECT
public:
    explicit worker(QObject *parent = nullptr);

private:

signals:

public slots:
    void onbuttonpush();

};

#endif // WORKER_H

#include "worker.h"
#include <QDebug>

#include <QThread>

worker::worker(QObject *parent)
    : QObject{parent}
{

}

void worker::onbuttonpush()
{
    qDebug()<<"worker::"<<QThread::currentThreadId();
}

#include "widget.h"
#include "ui_widget.h"
#include "mythread.h"
#include "worker.h"
#include <QThread>

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

    worker *work = new worker();
    QThread *thread = new QThread();
    work->moveToThread(thread);
    thread->start();

    connect(this,&Widget::push,work,&worker::onbuttonpush);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_pushButton_clicked()
{
    qDebug()<<"Widget::"<<QThread::currentThreadId();
    emit push();
}