Qt基礎(chǔ)開發(fā)之Qt多線程類QThread與Qt定時器類QTimer的詳細方法與實例

[virtual protected] void QThread::run()
 /*
 * 基類QThread的run函數(shù)只是簡單啟動exec()消息循環(huán)
 */

#include <QApplication>
#include <QThread>
#include <QDebug>
class MyThread : public QThread
{
public:
 void run()
 {
  qDebug() << "QThread begin" << endl;
  qDebug() << "child thread" << QThread::currentThreadId() << endl;
  QThread::sleep(5);
  qDebug() << "QThread end" << endl;
  exec();
 }
};
​
int main(int argc, char** argv)
{
 QApplication app(argc, argv);
​
 MyThread thread;
 thread.start();
 qDebug() << "main thread" << QThread::currentThreadId() << endl;
 QThread::sleep(5);
 qDebug() << "main thread" << QThread::currentThreadId() << endl;
 thread.quit();
 qDebug() << "main thread thread.quit()" << endl;
 tread.wait();
 qDebug() << "main thread thread.wait()" << endl;
 return app.exec();
}

#ifndef MYWORK_H
#define MYWORK_H
#include <QThread>
#include <QDebug>
class MyWork : public QObject
{
 Q_OBJECT
public slots:
 void workSlot()
 {
  qDebug() << "QThread begin" << endl;
  qDebug() << "child thread" << QThread::currentThreadId() << endl;
  QThread::sleep(5);
  qDebug() << "QThread end" << endl;
 }
};
#endif // MYWORK_H

#include <QApplication>
#include <QThread>
#include <QDebug>
#include "mywork.h"
​
int main(int argc, char** argv)
{
 qDebug() << "main thread" << QThread::currentThreadId() << endl;
 QApplication app(argc, argv);
 QThread thread;
 MyWork work;
 work.moveToThread(&thread);
 QObject::connect(&thread, SIGNAL(started()), &work, SLOT(workSlot()));
 thread.start();
 
 QThread::sleep(6);
 qDebug() << "thread is runing" << thread.isRunning() << endl;
 thread.quit(); //調(diào)用quit讓線程退出消息循環(huán),否則線程一直在exec循環(huán)中
 thread.wait(); //調(diào)用完quit后緊接著要調(diào)用wait來回收線程資源
 qDebug() << "thread is runing" << thread.isRunning() << endl;
​
 return app.exec();
}

#ifndef MYWORK_H
#define MYWORK_H
​
#include <QThread>
#include <QDebug>
class MyWork : public QObject
{
 Q_OBJECT
public:
​
 ~MyWork() { qDebug() << __FUNCTION__ << endl; }
public slots:
 void workSlot()
 {
  while(1)
  {
   qDebug() << "Work begin" << endl;
   QThread::sleep(5);
   qDebug() << "work end" << endl;
  }
 }
 void otherWorkSlot()
 {
  qDebug() << "otherWork begin" << endl;
  QThread::sleep(5);
  qDebug() << "otherWork end" << endl;
 }
​
​
};
​
#endif // MYWORK_H

#ifndef WIDGET_H
#define WIDGET_H
​
#include <QWidget>
#include "mywork.h"
​
class Widget : public QWidget
{
 Q_OBJECT
​
public:
 Widget(QWidget *parent = 0);
 ~Widget();
private:
 QThread *_thread;
 MyWork * _myWork;
};
​
#endif // WIDGET_H

#include "widget.h"
#include <QPushButton>
#include "mywork.h"
#include <QThread>
#include <QHBoxLayout>
​
Widget::Widget(QWidget *parent)
 : QWidget(parent)
{
 _myWork = new MyWork;
 _thread = new QThread(this);
 _myWork->moveToThread(_thread);
 _thread->start();
​
 QPushButton *pb0 = new QPushButton("work", this);
 QPushButton *pb1 = new QPushButton("pb", this);
 QHBoxLayout *hBox = new QHBoxLayout(this);
 hBox->addWidget(pb0);
 hBox->addWidget(pb1);
 this->setLayout(hBox);
​
 /*發(fā)射信號給在另外一個線程的對象的隊列中*/
 connect(pb0, SIGNAL(clicked()), _myWork, SLOT(workSlot()));
 connect(pb1, SIGNAL(clicked()), _myWork, SLOT(otherWorkSlot()));
​
 /*推薦用法釋放內(nèi)存*/
 //connect(_thread, SIGNAL(finished()), _myWork, SLOT(deleteLater()));
​
}
​
Widget::~Widget()
{
 _myWork->deleteLater(); //一定要在QThread線程退出之前
 _thread->quit();
 _thread->wait();
}

QMutex mutex; //這對象一般定義在多個線程能訪問的地方
mutex.lock(); //多個線程調(diào)用這個函數(shù)去獲取鎖，沒有獲取到的線程，將阻塞等待在這個函數(shù)上。
mutex.unlock(); //釋放鎖

bool QMutex::tryLock(int timeout = 0)
/*
*參數(shù) int timeout:等到timeout毫秒，不管有沒獲取到鎖都返回，timeout為0時，直接返回。
*返回值 true代表獲取到鎖，false沒有獲取到
*/

QMutex mutex;
void func()
{
 QMutexLocker locker(_mutex); //QMutexLocker最好實例化成棧對象，釋放之前將QMutex解鎖。 
}

QSemaphore sem(2) //初始化信號量為2
sem.acquire(); //信號量部位0的時候，調(diào)用這個函數(shù)會讓信號量-1，一旦信號量為零，阻塞等待
semaphore.release(); //使信號量+1

void start(int msec)
/*
*定時msec毫秒后，發(fā)射timeout()信號
*/

#include "dialog.h"
#include <QTimer>
#include <qdebug.h>
Dialog::Dialog(QWidget *parent)
 : QDialog(parent)
{
 QTimer *timer = new QTimer(this);
 connect(timer, SIGNAL(timeout()), this, SLOT(doSomeThing()));
 timer->start(3000);
 
}
void Dialog::doSomeThing()
{
 qDebug() << __FUNCTION__ << endl;
}
​
Dialog::~Dialog()
{
​
}