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Qt 多线程的两种实现方式

1. 从QThread类继承再重写 run 函数

实现流程：

1. 继承自QThread类
2. 重写run函数，其中run函数里面的代码为线程的执行代码
3. 调用start函数启动线程

程序示例：

• WorkThread.h 文件

#ifndef WORKTHREAD_H
#define WORKTHREAD_H#include <QThread>class WorkThread : public QThread
{Q_OBJECT
public:explicit WorkThread(QObject *parent = nullptr);~WorkThread();public:void StartThread();void StopThread();void TerminateThread();protected:void run() override;				// 重写run函数private:void DealValue(int& nValue);signals:void SignalSendValue(QString, int);private:bool m_bRunFlag;};#endif // WORKTHREAD_H

• WorkThread.cpp 文件

#include "WorkThread.h"
#include <QDebug>WorkThread::WorkThread(QObject *parent) : QThread(parent), m_bRunFlag(false)
{}WorkThread::~WorkThread()
{qDebug() << "Release WorkThread!";
}void WorkThread::StartThread()
{m_bRunFlag = true;start();
}void WorkThread::StopThread()
{m_bRunFlag = false;quit();wait();
}void WorkThread::TerminateThread()
{terminate();wait();
}void WorkThread::run()
{int nValue = 0;while (m_bRunFlag){DealValue(nValue);Qt::HANDLE hHandle = QThread::currentThreadId();emit SignalSendValue(QString::number(reinterpret_cast<quintptr>(hHandle), 16), nValue);QThread::msleep(100);}
}void WorkThread::DealValue(int &nValue)
{nValue++;if (nValue > 100)nValue = 1;
}

• MainWindow.h文件

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include "WorkThread.h"QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:void SlotRecieveValue(QString strThreadID, int nValue);private slots:void on_btnStart_clicked();void on_btnStop_clicked();void on_btnTerminate_clicked();private:Ui::MainWindow *ui;WorkThread* m_pWorkThread;
};
#endif // MAINWINDOW_H

• MainWindow.cpp文件

#include "MainWindow.h"
#include "ui_MainWindow.h"MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);ui->labelMainThreadID->setText(QString("Thread ID = 0x%1").arg(QString::number(reinterpret_cast<quintptr>(QThread::currentThreadId()), 16)));m_pWorkThread = new WorkThread(this);connect(m_pWorkThread, &WorkThread::SignalSendValue, this, &MainWindow::SlotRecieveValue);
}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::SlotRecieveValue(QString strThreadID, int nValue)
{ui->labelValue->setText(QString("Thread ID = 0x%1, Value = %2").arg(strThreadID).arg(nValue));
}void MainWindow::on_btnStart_clicked()
{m_pWorkThread->StartThread();
}void MainWindow::on_btnStop_clicked()
{m_pWorkThread->StopThread();
}void MainWindow::on_btnTerminate_clicked()
{m_pWorkThread->TerminateThread();
}

2. 使用QObject::moveToThread()函数

实现流程：

1. 创建一个工作类继承自QObject；
2. 创建一个工作类线程对象和一个QThread对象，调用QObject::moveToThread()将工作对象移至线程中；
3. 调用QThread对象的start函数，通过发送信号，后续工作对像的槽函数都会在独立的线程中执行；

文字解释流程相对比较抽象，下面看一个基于上面例子改造的示例；

• ThreadWorker.h 文件 (线程工作者对象)

#ifndef THREADWORKER_H
#define THREADWORKER_H#include <QObject>class ThreadWorker : public QObject
{Q_OBJECTpublic:explicit ThreadWorker(QObject *parent = nullptr);~ThreadWorker();public:void SetRunFlag(bool bRunFlag);public slots:void SlotDoWork();          // 槽函数，通过外部的信号关联，其执行会在独立的线程中private:void DealValue(int& nValue);signals:void SignalDoWork();void SignalSendValue(QString, int);private:bool m_bRunFlag;
};#endif // THREADWORKER_H

• ThreadWorker.cpp 文件

#include "ThreadWorker.h"
#include <QDebug>
#include <QThread>ThreadWorker::ThreadWorker(QObject *parent) : QObject(parent), m_bRunFlag(false)
{}ThreadWorker::~ThreadWorker()
{qDebug() << "Release ThreadWorker!";
}void ThreadWorker::SetRunFlag(bool bRunFlag)
{m_bRunFlag = bRunFlag;
}void ThreadWorker::SlotDoWork()
{int nValue = 0;while (m_bRunFlag){DealValue(nValue);Qt::HANDLE hHandle = QThread::currentThreadId();emit SignalSendValue(QString::number(reinterpret_cast<quintptr>(hHandle), 16), nValue);QThread::msleep(100);}
}void ThreadWorker::DealValue(int &nValue)
{nValue++;if (nValue > 100)nValue = 1;
}

• MainWindow.h 文件

#ifndef WORKTHREAD_H
#define WORKTHREAD_H#include <QThread>class WorkThread : public QThread
{Q_OBJECT
public:explicit WorkThread(QObject *parent = nullptr);~WorkThread();public:void StartThread();void StopThread();void TerminateThread();protected:void run() override;private:void DealValue(int& nValue);signals:void SignalSendValue(QString, int);private:bool m_bRunFlag;};#endif // WORKTHREAD_H

• MainWindow.cpp 文件

#include "WorkThread.h"
#include <QDebug>WorkThread::WorkThread(QObject *parent) : QThread(parent), m_bRunFlag(false)
{}WorkThread::~WorkThread()
{qDebug() << "Release WorkThread!";
}void WorkThread::StartThread()
{m_bRunFlag = true;start();
}void WorkThread::StopThread()
{m_bRunFlag = false;quit();wait();
}void WorkThread::TerminateThread()
{terminate();wait();
}void WorkThread::run()
{int nValue = 0;while (m_bRunFlag){DealValue(nValue);Qt::HANDLE hHandle = QThread::currentThreadId();emit SignalSendValue(QString::number(reinterpret_cast<quintptr>(hHandle), 16), nValue);QThread::msleep(100);}
}void WorkThread::DealValue(int &nValue)
{nValue++;if (nValue > 100)nValue = 1;
}