关于QT的movetothread用法

data 2018/10/24  add by WJB

在qt中使用多线程，以前的方法创建一个自己的thread的类，继承与QThread，然后重写run方法，从而实现多线程。交新版本的qt出现了movetoThread方法实现多线程。该方法由于使用起来比较灵活，得到广发应用；

首相要创建一个继承QObject的类（myobject），然后new一个Qthread，并把创建的myobject类movetothread到创建好的子线程中，然后start子线程，这样就实现了一个子线程。主线程通过发送信号，调用myobject中的方法，从而实现在子线程中的计算。

实例代码如下：

MyThread.h————————————————————————————————————————————————

#pragma once
#include <QObject>
#include <QDebug>
#include <QThread>
class MyThread :public QObject
{
    Q_OBJECT
public:
    MyThread();
    ~MyThread();

public slots:
    void first();
    void second();
    void three();

signals:
    void sig_sendfirst();
    void sig_sendsecond();
    void sig_sendThird();
};

MyThread.cpp

#include "MyThread.h"

MyThread::MyThread()
{
}
MyThread::~MyThread()
{
}

void MyThread::first()
{
    qDebug() <<"first"<< QThread::currentThreadId();
    sig_sendfirst();

}

void MyThread::second()
{
    qDebug() << "second" << QThread::currentThreadId();
    sig_sendsecond();

}

void MyThread::three()
{
    qDebug() << "three" << QThread::currentThreadId();
    sig_sendThird();
}
 

MovetoThreadTest.h

#include <QtWidgets/QMainWindow>
#include "ui_movetothreadtest.h"
#include "MyThread.h"

class MovetoThreadTest : public QMainWindow
{
    Q_OBJECT

public:
    MovetoThreadTest(QWidget *parent = 0);
    ~MovetoThreadTest();

public slots:
    void onSelfPushed();
    void onExitPushed();

    void slot_myfirst();
    void slot_mysecond();
    void slot_mythird();

    void slot_recivefirst();
    void slot_recivesecond();
    void slot_recivethird();

signals:
    void  sig_firt();
    void  sig_second();
    void  sig_third();
private:
    Ui::MovetoThreadTestClass ui;
    MyThread * m_pMyThread;
};

MovetoThreadTest.cpp

#include "movetothreadtest.h"

MovetoThreadTest::MovetoThreadTest(QWidget *parent)
    : QMainWindow(parent)
{
    qDebug() << "main" << QThread::currentThreadId();
    ui.setupUi(this);

    MyThread* m_pMyThread = new MyThread;
    QThread *thread = new QThread;
    m_pMyThread->moveToThread(thread);
    thread->start();
    connect(thread, SIGNAL(started()), m_pMyThread, SLOT(first()));
    //用不同的法师调用mythread的方法
    connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(slot_myfirst()), Qt::AutoConnection);

    connect(ui.pushButton_2, SIGNAL(clicked()), this, SLOT(slot_mysecond()), Qt::QueuedConnection);
    connect(ui.pushButton_3, SIGNAL(clicked()), m_pMyThread, SLOT(three()), Qt::QueuedConnection);

    connect(this, SIGNAL(sig_firt()), m_pMyThread, SLOT(first()), Qt::QueuedConnection);

    connect(ui.pushButton_4, SIGNAL(clicked()), this, SLOT(onSelfPushed()));
    connect(ui.pushButton_5, SIGNAL(clicked()), this, SLOT(onExitPushed()));

    //mythread 发出信号
    connect(m_pMyThread, SIGNAL(sig_sendfirst()), this, SLOT(slot_recivefirst()), Qt::QueuedConnection);
    connect(m_pMyThread, SIGNAL(sig_sendsecond()), this, SLOT(slot_recivesecond()), Qt::QueuedConnection);
    connect(m_pMyThread, SIGNAL(sig_sendThird()), this, SLOT(slot_recivethird()));
}

MovetoThreadTest::~MovetoThreadTest()
{

}

void MovetoThreadTest::onExitPushed()
{
    qDebug() << "onExitPushed" << QThread::currentThreadId();
}

void MovetoThreadTest::slot_myfirst()
{
    qDebug() << "slot_myfirst" << QThread::currentThreadId();
    emit sig_firt();
}

void MovetoThreadTest::slot_mysecond()
{
    qDebug() << "slot_mysecond" << QThread::currentThreadId();
    m_pMyThread->second();
}

void MovetoThreadTest::slot_mythird()
{
}

void MovetoThreadTest::slot_recivefirst()
{
    qDebug() << "slot_recivefirst" << QThread::currentThreadId();
}

void MovetoThreadTest::slot_recivesecond()
{
    qDebug() << "slot_recivesecond" << QThread::currentThreadId();
}

void MovetoThreadTest::slot_recivethird()
{
    qDebug() << "slot_recivethird" << QThread::currentThreadId();
}

void MovetoThreadTest::onSelfPushed()
{
    qDebug() << "onExitPushed" << QThread::currentThreadId();
}

MovetoThreadTest.cpp 中用到了窗体中的几个按钮，在如用代码是首相创建一个窗体，在窗体添加按钮，然后跟据按钮的名字进行连接即可；

主线程如果要在子线程中运行计算必须通过发信号的方式调用，或者通过控件的信号；需要说明在创建连接时如果第五的参数为DirectConnection时，调用的槽函数是在主线程中运行；如果想通过子线程向主线程调用方法，也必须通过发信号的方式触发主线程的函数。