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详解Qt中线程的使用方法

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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 = 0);
    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 = 0);
    ~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()%1000; //取随机数
        //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
 
        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(1);
    sp_B = new QSemaphore(0);
 
}
 
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

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