QT多线程创建的误区：run函数

直接上代码吧，注意这种方法创建的多线程，只有run函数内的属于新的线程，OnTempTimer()虽然是run函数调用的，但是是主线程在执行，一定要注意啊。这样弄相当于没有任何意义，还是主线程在处理函数。
下一个博客有讲怎么实现多线程的正确创建和使用

MainWindow.cpp

MysqlThread = new ReconnectMysql();
    MysqlThread->start();

reconnectmysql.cpp

#include "reconnectmysql.h"

ReconnectMysql::ReconnectMysql()
{

}

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

    //Timer = new QTimer(this);这样写会报错：
    //Parent is ReconnectMysql(0xd621978), parent's thread is QThread(0x4ac5dd0),
    //current thread is ReconnectMysql(0xd621978)

    Timer = new QTimer();//或者Timer = new QTimer(NULL);
    //这句话也要在run()不能像这样给定时器指定父对象 Timer = new QTimer(this);
    Timer->start(1000);
    connect(Timer, SIGNAL(timeout()), this, SLOT(OnTempTimer()));
    this->exec();//不加这句话定时器不执行
}

void ReconnectMysql::OnTempTimer()
{
    qDebug()<< "OnTempTimer()";
}

reconnectmysql.h 注意继承的QThread

#ifndef RECONNECTMYSQL_H
#define RECONNECTMYSQL_H

#include <QObject>
#include <QThread>
#include <QTimer>
#include <QDebug>

class ReconnectMysql : public QThread
{
    Q_OBJECT
public:
    explicit ReconnectMysql();
    void run();

signals:

public slots:
    void OnTempTimer();
private:
    QTimer *Timer;

};

#endif // RECONNECTMYSQL_H

打印：

怎么验证以上的说法呢，很简单，用这个函数QThread::currentThreadId();获取当前线程的ID

    qDebug()<<tr("主线程id:")<<QThread::currentThreadId();
   
    //多线程方式1
    myThread = new MyThread();
    myThread->start();

void MyThread::run()//只有run()里面在新的线程里
{
    qDebug()<<tr("mythread QThread::currentThreadId()==")<<QThread::currentThreadId();

//这种方式还是相当于在主线程里面执行
    timer= new QTimer(NULL);
    connect(timer, SIGNAL(timeout()), this, SLOT(onTimeout()));
    timer->start(1000);
    this->exec();
    }

//这种方式还是相当于在主线程里面执行
void MyThread::onTimeout()
{
    qDebug()<<tr("mythread QThread::currentThreadId()==")<<QThread::currentThreadId();
    qDebug()<<"globalCount: " << ++globalCount;

}