19、Qt线程（四）：继承QRunnable类

一、功能说明

1、通过继承QRunnable，重写run的方式实现多线程

2、点击“开始”按钮启动子线程；

二、项目创建

1、新建Qt Widgets Application应用，名称为Runnable，基类选择QMainWindow；

2、MainWindow.ui中放入一个Push Button按钮，第一个text改为“开始”，objectNme改为startPushButton；

3、添加新的C++类，名称为MyRunnable，基类设置为QRunnable

4、注：

QRunnable的使用方式与QThread类似，但是QRunnable不能使用信号槽，可以使用QMetaObject::invokeMethod()

三、代码展示

1、myrunnable.h

#ifndef MYRUNNABLE_H
#define MYRUNNABLE_H#include <QRunnable>
#include <QWidget>class MyRunnable : public QRunnable
{
public:explicit MyRunnable();~MyRunnable();protected:void run();
};#endif // MYRUNNABLE_H

2、myrunnable.cpp

#include "myrunnable.h"
#include <QDebug>
#include <QThread>MyRunnable::MyRunnable()
{qDebug() << "MyRunnable(): " << QThread::currentThreadId();
}MyRunnable::~MyRunnable()
{qDebug() << "~MyRunnable(): " << QThread::currentThreadId();
}void MyRunnable::run()
{qDebug() << "MyRunnable::run()" << QThread::currentThreadId();
}

3、mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include "myrunnable.h"namespace Ui {
class MainWindow;
}class MainWindow : public QMainWindow
{Q_OBJECTpublic:explicit MainWindow(QWidget *parent = nullptr);~MainWindow();private slots:void on_startPushButton_clicked();private:Ui::MainWindow *ui;MyRunnable *m_myRunnable;
};#endif // MAINWINDOW_H

4、mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QThread>
#include <QDebug>
#include <QThreadPool>MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{ui->setupUi(this);m_myRunnable = new MyRunnable;qDebug() << "MainWindow() " << QThread::currentThreadId();
}MainWindow::~MainWindow()
{if(!m_myRunnable){delete m_myRunnable;m_myRunnable = nullptr;}delete ui;
}void MainWindow::on_startPushButton_clicked()
{qDebug() << "on_startPushButton_clicked() " << QThread::currentThreadId();QThreadPool::globalInstance()->start(m_myRunnable);
}