QT中使用线程可以提高工作效率。
要使用线程要经过一下四个步骤:
(1)先创建一个c++ class文件,记得继承Thread,创建步骤如下:
a、第一步
b、第二步
(2)自定义一个run函数,以后启动线程的时候,程序就会跳转到run函数中
void run();
(3)初始化线程
HDThread mythread = new HDThread();
(4)启动线程
mythread->start();
下面来看看线程使用的具体列子:
线程头文件hdthread.h:
#ifndef HDTHREAD_H
#define HDTHREAD_H
#include <QThread>
#include <QLabel>
#include <QMutex> class HDTHread : public QThread
{
public:
HDTHread(QMutex* mtex,QObject *parent = );
void run();//自定义的run函数
void setLabel(QLabel *lb);
private:
QLabel *label;
QMutex *mutex; //互斥锁
}; #endif // HDTHREAD_H
主函数的头文件threadqt.h
#ifndef THREADQT_H
#define THREADQT_H #include <QMainWindow>
#include <hdthread.h>
#include <writefile.h>
#include <QMutex>
#include <QSemaphore> namespace Ui {
class ThreadQt;
} class ThreadQt : public QMainWindow
{
Q_OBJECT public:
explicit ThreadQt(QWidget *parent = );
~ThreadQt(); //定义静态的信号类
static QSemaphore *sp_A;
static QSemaphore *sp_B;
private slots:
void on_pushButton_clicked(); private:
Ui::ThreadQt *ui; HDTHread *thread; //hdtread类,里面继承了线程
WriteFile *writethread;
QMutex mutex;//定义互斥锁类 }; #endif // THREADQT_H
源文件hdthread.cpp:
#include "hdthread.h"
#include <QDebug>
#include <threadqt.h>
HDTHread::HDTHread(QMutex *mtex, QObject *parent):QThread(parent)//构造函数,用来初始化
{
this->mutex = mtex;
}
void HDTHread::setLabel(QLabel *lb)
{
this->label = lb;
} void HDTHread::run() //启动线程时执行的函数
{
while(true)
{ qint64 data = qrand()%; //取随机数
//this->mutex->lock();//上锁
ThreadQt::sp_A->acquire();//请求信号
this->label->setText(QString::number(data));
sleep();
ThreadQt::sp_B->release();//释放信号
//this->mutex->unlock();//解锁 qDebug()<<"hello Qt"<<data;
}
}
源文件threadqt.cpp
#include "threadqt.h"
#include "ui_threadqt.h" //初始化静态变量
QSemaphore *ThreadQt::sp_A = NULL;
QSemaphore *ThreadQt::sp_B = NULL; ThreadQt::ThreadQt(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::ThreadQt)
{
ui->setupUi(this);
//创建信号对象
sp_A = new QSemaphore();
sp_B = new QSemaphore(); } ThreadQt::~ThreadQt()
{
delete ui;
} void ThreadQt::on_pushButton_clicked()
{
thread = new HDTHread(&mutex); //初始化线程
thread->setLabel(ui->label);
thread->start();//开启线程 writethread = new WriteFile(&mutex);
writethread->setLabel(ui->label);
writethread->start();
}
大家也看到了,此处的线程也用到了互斥锁(信号量)保证线程读写数据时不出现错误,这里大家可以看一下具体实现的代码
this->mutex->lock();//上锁
ThreadQt::sp_A->acquire();//请求信号
this->label->setText(QString::number(data));
sleep(1);
ThreadQt::sp_B->release();//释放信号
this->mutex->unlock();//解锁