在Qt中，使用线程主要有两种方式。

1、自定义线程类，继承自QThread，并重写run方法即可。该方法就不再阐述了。

2、就是推荐使用的方法。

示例代码如下：

1、自定义Worker类，将线程中的逻辑在该类中以槽函数的方式实现：

Worker.h

#ifndef WORKER_H
#define WORKER_H#include <QObject>class Worker : public QObject
{Q_OBJECT
public:explicit Worker(QObject *parent = nullptr);~Worker();public slots:void doSomething();
};#endif // WORKER_H

Worker.cpp

#include "worker.h"
#include <QDebug>Worker::Worker(QObject *parent) : QObject(parent)
{}Worker::~Worker()
{qDebug()<<"free worker...";
}void Worker::doSomething()
{qDebug()<<"do something...";
}

2、调用处的代码

    QThread *thread = new QThread;Worker* worker = new Worker;connect(thread,SIGNAL(started()),worker,SLOT(doSomething()));connect(thread,SIGNAL(finished()),worker,SLOT(deleteLater()));connect(thread,SIGNAL(finished()),thread,SLOT(deleteLater()));worker->moveToThread(thread);thread->start();

以上代码非常清晰易懂，在线程开始的时候触发Worker的doSomething槽函数，当线程结束的时候调用Worker的deleteLater槽函数以释放new出来的worker对象和thread对象。

但是问题出现了！thread线程永远不会结束！其原因是虽然worker对象的doSomething槽函数结束了，但是thread线程依然处于自己的事件循环中！也就导致了thread和worker的内存泄漏！

正确的处理办法：在worker对象的槽函数doSomething结束的时候，应发射结束信号来间接控制线程！具体代码如下：

Worker.h

#ifndef WORKER_H
#define WORKER_H#include <QObject>class Worker : public QObject
{Q_OBJECT
public:explicit Worker(QObject *parent = nullptr);~Worker();
signals:void finished();//完成信号public slots:void doSomething();
};#endif // WORKER_H

Worker.cpp

#include "worker.h"
#include <QDebug>Worker::Worker(QObject *parent) : QObject(parent)
{}Worker::~Worker()
{qDebug()<<"free worker...";
}void Worker::doSomething()
{qDebug()<<"do something...";emit finished();
}

调用处代码：

    QThread *thread = new QThread;Worker*worker = new Worker;connect(worker,SIGNAL(finished()),thread,SLOT(quit()));//新增connect(thread,SIGNAL(started()),worker,SLOT(doSomething()));connect(thread,SIGNAL(finished()),worker,SLOT(deleteLater()));connect(thread,SIGNAL(finished()),thread,SLOT(deleteLater()));worker->moveToThread(thread);thread->start();

这样就可以保证，在worker对象结束任务时，thread也退出了事件循环并发射finished信号且释放内存！