QT 多線程（QThread）裡調用線程池（QThreadPool ）與主界面進行通訊

在最近的一個項目中，遇到了一個問題，就是主界面調用一個線程，然後再線程中開啟一個線程池進行資料生成，線程池調用的線程對象必須繼承自QRunable類，這個類有個缺點，就是因為它無法繼承QObject，是以不能向外面發送信号，但是我們需要在主界面顯示它輸出的資訊。怎麼辦呢？

• 編寫一個QRunable子類
• 編寫一個QThread子類
• 調用QThread子類

編寫一個QRunable子類

編寫一個QRunable子類MyRunable

MyRunable.h代碼，如下：

#ifndef MYRUNNABLE_H
#define MYRUNNABLE_H

#include <QRunnable>
#include <QMetaObject>

class MyRunnable : public QRunnable
{
public:
    MyRunnable(QObject *parent = );
    ~MyRunnable();

    void run();

    void setID(const int &id);
    //向外傳送消息
    void requestMsg(const QString &msg);
private:
    //父對象
    QObject *mParent;

    int runnableID;
};

#endif // MYRUNNABLE_H
           

MyRunable.cpp代碼，如下：

#include "myrunnable.h"
#include <QDebug>
#include <QThread>
MyRunnable::MyRunnable(QObject *parent)
    : QRunnable()
{
    mParent = parent;
}

MyRunnable::~MyRunnable()
{
    runnableID = ;
}

void MyRunnable::setID(const int &id)
{
    runnableID = id;
}

void MyRunnable::requestMsg(const QString &msg)
{
    QMetaObject::invokeMethod(mParent, "requestMsg", Qt::QueuedConnection, Q_ARG(QString, msg));
}

void MyRunnable::run()
{
    for(int i = ;i < ;i++)
    {
        requestMsg(QString("this is a MyRunnable %1").arg(runnableID));
        QThread::sleep();
    }
}
           

編寫一個QThread子類

編寫一個QThread子類MyThread

MyThread.h代碼，如下：

#ifndef MYTHREAD_H
#define MYTHREAD_H

#include <QThread>

class MyThread : public QThread
{
    Q_OBJECT
public:
    explicit MyThread(QObject *parent = );

protected:
    void run();

signals:
    void requestMsg(const QString &msg);

public slots:

};

#endif // MYTHREAD_H
           

MyThread.cpp代碼，如下：

#include "mythread.h"
#include <QThreadPool>
#include "myrunnable.h"
#include <QDebug>
MyThread::MyThread(QObject *parent) :
    QThread(parent)
{
}

void MyThread::run()
{
    qDebug() << "MyThread";

    QThreadPool myPool;
    myPool.setMaxThreadCount();
    for(int i = ;i < ;i++)
    {
        MyRunnable *subThread = new MyRunnable(this);
        subThread->setID(i);
        myPool.start(subThread);
    }

    myPool.waitForDone();
}
           

調用QThread子類

在MainWindow中調用MyThread并關聯信号槽

MainWindow .h代碼，如下：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "mythread.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = );
    ~MainWindow();
private slots:
    void showMsg(const QString &msg);
private:
    Ui::MainWindow *ui;

    MyThread myThread;
};

#endif // MAINWINDOW_H
           

MainWindow .cpp代碼，如下：

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QDateTime>

#include <QThreadPool>
#include <myrunnable.h>


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    connect(&myThread,SIGNAL(requestMsg(const QString&)),this,SLOT(showMsg(const QString&)));
    myThread.start();
}

void MainWindow::showMsg(const QString &msg)
{
    qDebug()<< msg;
}
           

運作結果

MyThread
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
"this is a MyRunnable 0"
"this is a MyRunnable 1"
"this is a MyRunnable 2"
"this is a MyRunnable 3"
           

歡迎大家指正…