How to use the QT middle thread

Using threads in QT can improve productivity.

To use a thread, go through four steps:

(1) First create a C + + class file, remember to inherit the thread, create the following steps:

A, the first step

B, Step two

(2) Customizing a run function, the program jumps to the run function when the thread is started later

void run ();

(3) Initialize thread

New Hdthread ();

(4) Start thread

Mythread->start ();

Here's a look at the specific examples of threading usage:

Thread header file Hdthread.h:

1 #ifndef Hdthread_h2 #defineHdthread_h3#include <QThread>4#include <QLabel>5#include <QMutex>6 7 classHdthread: PublicQthread8 {9  Public:TenHdthread (qmutex* mtex,qobject *parent =0); One     voidRun ();//the custom run function A     voidSetLabel (Qlabel *lb); - Private: -Qlabel *label; theQmutex *mutex;//Mutual exclusion Lock - }; -  - #endif //Hdthread_h

Header file for main function threadqt.h

1 #ifndef Threadqt_h2 #defineThreadqt_h3 4#include <QMainWindow>5#include 6#include <writefile.h>7#include <QMutex>8#include <QSemaphore>9 Ten namespaceUi { One classTHREADQT; A } -  - classTHREADQT: PublicQmainwindow the { - Q_object -  -  Public: +     ExplicitTHREADQT (Qwidget *parent =0); -~THREADQT (); +  A      //defining a static signal class at     StaticQsemaphore *sp_a; -     StaticQsemaphore *sp_b; - PrivateSlots: -     voidon_pushbutton_clicked (); -  - Private: inUI::THREADQT *UI; -  toHdthread *thread;//Hdtread class, which inherits the thread +WriteFile *Writethread; - Qmutex mutex;//defining mutex Classes the  * }; $ Panax Notoginseng #endif //Threadqt_h

Source file Hdthread.cpp:

#include"hdthread.h"#include<QDebug>#include<threadqt.h>Hdthread::hdthread (Qmutex*mtex, Qobject *parent): Qthread (parent)//constructor, which is used to initialize the{     This->mutex =Mtex;}voidHdthread::setlabel (Qlabel *lb) {     This->label =lb;}voidHdthread::run ()//functions to execute when starting a thread{     while(true) {Qint64 data= Qrand ()% +;//take a random number//This->mutex->lock ();//lockedThreadqt::sp_a->acquire ();//Request Signal         This->label->SetText (Qstring::number (data)); Sleep (1); Threadqt::sp_b->release ();//Release Signal//This->mutex->unlock ();//UnlockQdebug ()<<"Hello Qt"<<data; }}

Source file Threadqt.cpp

#include"threadqt.h"#include"ui_threadqt.h"//Initializing static variablesQsemaphore *threadqt::sp_a =NULL; Qsemaphore*threadqt::sp_b =NULL; THREADQT::THREADQT (Qwidget*parent): Qmainwindow (parent), UI (NewUI::THREADQT) {UI->SETUPUI ( This); //creating a Signal objectSp_a =NewQsemaphore (1); Sp_b=NewQsemaphore (0);} THREADQT::~threadqt () {DeleteUI;}voidthreadqt::on_pushbutton_clicked () {thread=NewHdthread (&mutex); Initializing Threads thread->setlabel (ui->label); Thread->start ();//Open ThreadWritethread=NewWriteFile (&mutex); Writethread->setlabel (ui->label); Writethread-start ();}

As you can see, the thread here also uses the mutex (semaphore) to ensure that the thread reads and writes the data without errors, so here's a look at the implementation code.

This->mutex->lock ();//lockout threadqt::sp_a->acquire ();//Request Signal This->label->settext (QString::number ( data)); Sleep (1); Threadqt::sp_b->release ();//Release Signal this->mutex->unlock ();//unlock

How to use the QT middle thread