Qt學習之如何啓動一個線程

以前看過在linux下C編程的線程書籍，今天來看看Qt如何啓動一個線程吧，代碼就以精通Qt4編程的爲例

先來給出每個文件的相關代碼然後再加以分析

//*************dialog.h**************//

 

#ifndef DIALOG_H

#define DIALOG_H

#include <QDialog>

#define MAXSIZE 5  //最大的線程數

class QDialogButtonBox;

class QProgressBar;

class QPushButton;

class WorkThread;

class ThreadDlg : public QDialog

{

    Q_OBJECT

public:

    ThreadDlg(QWidget *parent = 0);

public slots:

		void start();   

		void stop();

private:

    QPushButton *startButton;

    QPushButton *quitButton;

    QPushButton *stopButton;

    QDialogButtonBox *buttonBox;

		WorkThread* threadVector[MAXSIZE];

};

#endif

//***********end end end************//

 

//***********mainwindow.h************//

 

#ifndef WORKTHREAD_H

#define WORKTHREAD_H

#include <QThread>

class WorkThread : public QThread

{

 protected:

     void run();   //重新實現run()函數

};

#endif

//***********end end end************//

 

 

//***********dialog.cpp************//

 

#include <QtGui>

#include "workThread.h"

#include "dialog.h"

ThreadDlg::ThreadDlg(QWidget *parent)     

    : QDialog(parent)

{

    startButton = new QPushButton(tr("開始"));

    quitButton = new QPushButton(tr("退出"));

		stopButton = new QPushButton(tr("停止"));

		stopButton->setEnabled(false);

    buttonBox = new QDialogButtonBox;

    buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);

		buttonBox->addButton(stopButton, QDialogButtonBox::ActionRole);

    buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

    connect(startButton, SIGNAL(clicked()), this, SLOT(start()));

    connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));

    connect(stopButton, SIGNAL(clicked()), this, SLOT(stop()));

    QVBoxLayout *mainLayout = new QVBoxLayout;

    mainLayout->addWidget(buttonBox);

    setLayout(mainLayout);

    setWindowTitle(tr("啓動線程"));

}

void ThreadDlg::start()

{

	for(int i=0;i<MAXSIZE;i++)

	{

		threadVector[i] = new WorkThread();   //創建線程

	}

		for(int i=0;i<MAXSIZE;i++)

	{

		threadVector[i]->start(QThread::LowestPriority);   //啓動線程同時設置它的優先級，當然也可以不帶，使用默認的優先級

	}

	stopButton->setEnabled(true);

	startButton->setEnabled(false);

}

void ThreadDlg::stop()

{

	for(int i=0;i<MAXSIZE;i++)

	{

		threadVector[i]->terminate();    //終止線程

		threadVector[i]->wait();    //阻塞等待

	}

	startButton->setEnabled(true);

	stopButton->setEnabled(false);

}

 

//***********end end end************//

 

//***********mainwindow.cpp************//

 

#include "workThread.h"

#include "dialog.h"

#include <QTextEdit>

#include <QDebug>

#include <stdio.h>

 void WorkThread::run()

 {

     while(true)

		 for (int n = 0; n < 10;++n) {

					printf("%d/n",n);  //打印輸出

     }

 }

//***********end end end************//

 

//***********main.cpp************//

 

#include <QApplication>

#include <QtCore>

#include "dialog.h"

int main(int argc, char *argv[])

{

    QApplication app(argc, argv);

	QTextCodec::setCodecForTr( QTextCodec::codecForName("gb2312"));	

    ThreadDlg dialog;

    dialog.show();

    return dialog.exec();

}

//***********end end end************//

以上代碼簡單，沒有必要做過多的講解，但是其中的“threadVector[i]->terminate(); ”有必要講解下，terminate()函數的調用便不會立刻終止線程，因爲線程的何時終止取決於系統的調度策略，所在在之後又調用了wait()函數是的線程阻塞等待直到退出或者超時。

最後加以一點就是在.pro文件中加入一行代碼才能成功運行：

CONFIG+=thread