qt 线程

qt线程创建有两种方式：

1、信号槽形式

2、继承QThread形式。

这里记一下信号槽形式。参考：https://blog.csdn.net/douzhq/article/details/104156580

worker.h

 1 #ifndef WORKER_H
 2 #define WORKER_H
 3 
 4 #include <QObject>
 5 class Worker : public QObject
 6 {
 7     Q_OBJECT
 8 
 9 public:
10     Worker(QObject* parent = nullptr);
11     ~Worker();
12 
13 public slots:
14     // 计算前count个数的和
15     void doWork(int count);
16 
17 signals:
18     // 发送计算完成信号
19     void doFinished(int);
20 };
21 
22 #endif

worker.cpp

 1 #include "Worker.h"
 2 #include <QDebug>
 3 #include <QThread>
 4 
 5 Worker::Worker(QObject* parent)
 6     :QObject(parent)
 7 {
 8 
 9 }
10 
11 Worker::~Worker()
12 {
13 
14 }
15 
16 // 计算 0~count个数的和
17 void Worker::doWork(int count)
18 {
19     int sum = 0;
20     for (int i=0; i<=count; ++i)
21         sum += i;
22 
23     // 打印当前函数名，线程ID，以及计算结果
24     qDebug() << __FUNCTION__ << "Thread ID: " << QThread::currentThreadId() << ", Result is " << sum;
25 
26     emit doFinished(sum);
27 }

controller.h

 1 #ifndef MYOBJECT_H
 2 #define MYOBJECT_H
 3 
 4 #include <QObject>
 5 #include <QThread>
 6 
 7 class Controller : public QObject
 8 {
 9     Q_OBJECT
10 
11 public:
12     Controller(QObject* parent = nullptr);
13     ~Controller();
14 
15     // 开启线程计算
16     void startThreadRunFunc(int number);
17 
18 private:
19     QThread m_thread;
20 
21 signals:
22     // 该信号用于触发工作者中的槽函数
23     void startCalcSum(int);
24 
25 private slots:
26     // 接受计算完毕后的结果槽函数
27     void onCalcSumFinished(int sum);
28 };
29 
30 #endif

controller.cpp

 1 #include "Controller.h"
 2 #include "Worker.h"
 3 #include <QDebug>
 4 
 5 Controller::Controller(QObject* parent)
 6     :QObject (parent)
 7 {
 8     // [1]
 9     Worker* worker = new Worker;
10     worker->moveToThread(&m_thread);
11 
12     // [2]
13     QObject::connect(this, &Controller::startCalcSum, worker, &Worker::doWork);
14     // [3]
15     QObject::connect(worker, &Worker::doFinished, this, &Controller::onCalcSumFinished);
16 
17     // [4] 当线程退出时，释放工作者内存
18     QObject::connect(&m_thread, &QThread::finished, worker, &Worker::deleteLater);
19 
20     // [5]
21     m_thread.start();
22 }
23 
24 Controller::~Controller()
25 {
26     m_thread.quit();
27     m_thread.wait();
28 }
29 
30 void Controller::startThreadRunFunc(int number)
31 {
32     // 发送开始计算信号
33     emit startCalcSum(number);
34     qDebug() << __FUNCTION__ << " : Current Thread is " << QThread::currentThreadId();
35 }
36 
37 void Controller::onCalcSumFinished(int sum)
38 {
39     // 打印行数名，当前线程ID，计算结果
40     qDebug() << __FUNCTION__ \
41              << " : Current Thread is " << QThread::currentThreadId() \
42              << ", Result is " << sum;
43 }

调用方法：

#include <QCoreApplication>
#include <QThread>
#include "Controller.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // 创建控制器
    Controller *object = new Controller;
    // 计算前100个数的和
    object->startThreadRunFunc(100);

    return a.exec();
}

执行结果如下：
Controller::startThreadRunFunc : Current Thread is 0x491c
Worker::doWork Thread ID: 0x62c0 , Result is 5050
Controller::onCalcSumFinished : Current Thread is 0x491c , Result is 5050

整体流程如下：

函数 startThreadRunFunc 发送信号 startCalcSum ，此过程在主线程中执行。
触发 doWork 槽函数，计算前100个数的和，并发送信号 doFinished 信号，此过程在新建的线程中执行。
触发 onCalcSumFinished 槽函数，此过程在主线程中执行。