快捷導(dǎo)航

Qt5.9繼承QObject創(chuàng)建多線程實(shí)例

更新時(shí)間：2021年09月24日 10:31:41 作者：三公子Tjq

本文主要介紹了Qt5.9繼承QObject創(chuàng)建多線程實(shí)例，文中通過示例代碼介紹的非常詳細(xì)，具有一定的參考價(jià)值，感興趣的小伙伴們可以參考一下

本博客主要總結(jié)Qt中創(chuàng)建多線程的另一種方法，不是通過繼承類QThread，而是通過繼承對(duì)象QObject，來實(shí)現(xiàn)多線程。（可以直接跳過下面內(nèi)容，看1.1內(nèi)容）

利用繼承QObject方法創(chuàng)建多線程，主要的步驟有一下幾點(diǎn)：（注意：退出線程循環(huán)后，還要調(diào)用QThread::quit()函數(shù)，該線程才會(huì)觸發(fā)QThread::finished()信號(hào)）

a1：首先創(chuàng)建一個(gè)類MyThread，基類為QObject。

a2：在類MyThread中創(chuàng)建一個(gè)槽函數(shù)，用于運(yùn)行多線程里面的代碼。所有耗時(shí)代碼，全部在這個(gè)槽函數(shù)里面運(yùn)行。

a3：實(shí)例一個(gè)QThread線程對(duì)象（容器），將類MyThread的實(shí)例對(duì)象轉(zhuǎn)到該容器中，用函數(shù)void QObject::moveToThread(QThread *thread);

myObjectThread->moveToThread(firstThread);

a4：用一個(gè)信號(hào)觸發(fā)該多線程槽函數(shù)，比如用QThread::started()信號(hào)。

connect(firstThread,SIGNAL(started()),myObjectThread,SLOT(startThreadSlot()));

a5：用信號(hào)QThread::finished綁定槽函數(shù)QThread::deleteLatater()，在線程退出時(shí)，銷毀該線程和相關(guān)資源。

connect(firstThread,SIGNAL(finished()),firstThread,SLOT(deleteLater()));

a6：所有線程初始化完成后，啟動(dòng)函數(shù)QThread::start()開啟多線程，然后自動(dòng)觸發(fā)多線程啟動(dòng)信號(hào)QThread::started()。

具體的教程如下圖所示：

1.1新建一個(gè)widget工程，不要勾選ui界面。然后分別在mythread.h，mythread.cpp，widget.h，widget.cpp，main.cpp分別添加如下代碼。

mythread.h

#ifndef MYTHREAD_H
#define MYTHREAD_H
 
#include <QObject>
 
class MyThread : public QObject
{
    Q_OBJECT
public:
    explicit MyThread(QObject *parent = nullptr);
 
    void closeThread();
 
signals:
 
public slots:
    void startThreadSlot();
 
private:
    volatile bool isStop;
};
 
#endif // MYTHREAD_H

mythread.cpp

#include "mythread.h"
#include <QDebug>
#include <QThread>
 
MyThread::MyThread(QObject *parent) : QObject(parent)
{
    isStop = false;
}
 
void MyThread::closeThread()
{
    isStop = true;
}
 
void MyThread::startThreadSlot()
{
    while (1)
    {
        if(isStop)
            return;
        qDebug()<<"MyThread::startThreadSlot QThread::currentThreadId()=="<<QThread::currentThreadId();
        QThread::sleep(1);
    }
}

widget.h

#ifndef WIDGET_H
#define WIDGET_H
 
#include <QWidget>
#include <QVBoxLayout>
#include <QPushButton>
#include <QThread>
#include "mythread.h"
 
class Widget : public QWidget
{
    Q_OBJECT
 
public:
    Widget(QWidget *parent = 0);
    ~Widget();
 
    void createView();
 
private slots:
    void openThreadSlot();
    void closeThreadSlot();
    void finishedThreadSlot();
 
private:
    QVBoxLayout *mainLayout;
    QThread *firstThread;
    MyThread *myObjectThread;
};
 
#endif // WIDGET_H

widget.cpp

#include <QDebug>
#include "widget.h"
 
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    createView();
}
 
Widget::~Widget()
{
}
 
void Widget::createView()
{
    /*UI界面*/
    mainLayout = new QVBoxLayout(this);
    QPushButton *openThreadBtn = new QPushButton(tr("打開線程"));
    QPushButton *closeThreadBtn = new QPushButton(tr("關(guān)閉線程"));
    mainLayout->addWidget(openThreadBtn);
    mainLayout->addWidget(closeThreadBtn);
    mainLayout->addStretch();
    connect(openThreadBtn,SIGNAL(clicked(bool)),this,SLOT(openThreadSlot()));
    connect(closeThreadBtn,SIGNAL(clicked(bool)),this,SLOT(closeThreadSlot()));
}
 
void Widget::openThreadSlot()
{
    /*開啟一條多線程*/
    qDebug()<<tr("開啟線程");
    firstThread = new QThread;                                                      //線程容器
    myObjectThread = new MyThread;
    myObjectThread->moveToThread(firstThread);                                      //將創(chuàng)建的對(duì)象移到線程容器中
    connect(firstThread,SIGNAL(finished()),myObjectThread,SLOT(deleteLater()));        //終止線程時(shí)要調(diào)用deleteLater槽函數(shù)
    connect(firstThread,SIGNAL(started()),myObjectThread,SLOT(startThreadSlot()));  //開啟線程槽函數(shù)
    connect(firstThread,SIGNAL(finished()),this,SLOT(finishedThreadSlot()));
    firstThread->start();                                                           //開啟多線程槽函數(shù)
    qDebug()<<"mainWidget QThread::currentThreadId()=="<<QThread::currentThreadId();
}
 
void Widget::closeThreadSlot()
{        
    qDebug()<<tr("關(guān)閉線程");
    if(firstThread->isRunning())
    {
        myObjectThread->closeThread();  //關(guān)閉線程槽函數(shù)
        firstThread->quit();            //退出事件循環(huán)
        firstThread->wait();            //釋放線程槽函數(shù)資源
    }
}
 
void Widget::finishedThreadSlot()
{
    qDebug()<<tr("多線程觸發(fā)了finished信號(hào)123");
}

main.cpp

#include "widget.h"
#include <QApplication>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.resize(960,640);
    w.show();
 
    return a.exec();
}

1.2程序構(gòu)建和運(yùn)行后，結(jié)果如下圖所示：