Qt 中多线程的处理

在Qt中使用多线程要在类中继承QThread类：

#ifndef _THREAD_H_
#define _THREAD_H_
#include <QThread>
#include <QString>
class Thread:public QThread
{
public:
    Thread();
    void setMessage(const QString &message);
    void run();
    void stop();
private:
    QString messageStr;
    volatile bool stopped;

};
#endif

下面是线程类的实现：

#include "thread.h"
#include<iostream>
using namespace std;

Thread::Thread()
{
stopped=false;
messageStr="a";
}

void Thread::run()
{
while(!stopped)
   cout<<messageStr.toStdString ();
stopped=false;
cerr<<endl;
}

void Thread::stop()
{
stopped=true;
}

void Thread::setMessage(const QString &message)
{
messageStr=message;
}

UI界面的设计类：

#ifndef _THREADFORM_H_
#define _THREADFORM_H_
#include<QtGui>
#include "thread.h"

class QPushButton;
class ThreadForm:public QDialog
{
Q_OBJECT
public:      
ThreadForm(QWidget *parent=0);
protected:
void closeEvent(QCloseEvent *event);
private slots:
   void startOrStopTheadA();
   void startOrStopTheadB();
private:
Thread threadA;
Thread threadB;
QPushButton *threadAButton;
QPushButton *threadBButton;
QPushButton *quitButton;

};

#endif

GUI界面的实现：

#include "ui_thread.h"

ThreadForm::ThreadForm(QWidget *parent):QDialog(parent)
{
setWindowTitle(tr("Threads"));
threadA.setMessage("thread A");
threadB.setMessage("thread B");

threadAButton=new QPushButton(tr("start A"));
threadBButton=new QPushButton(tr("start B"));
quitButton=new QPushButton(tr("quit"));

QHBoxLayout *hbox=new QHBoxLayout(this);
hbox->addWidget(threadAButton);
hbox->addWidget(threadBButton);
hbox->addWidget(quitButton);
//quitButton->setDefault(true);
connect(threadAButton,SIGNAL(clicked() ),this, SLOT( startOrStopTheadA() ));
connect(threadBButton,SIGNAL(clicked() ),this, SLOT( startOrStopTheadB() ));
connect(quitButton,SIGNAL(clicked() ),this, SLOT( close() ));
}

void ThreadForm::startOrStopTheadA()
{
if(threadA.isRunning())
{
   threadA.stop();
   threadAButton->setText(tr("start A"));
}
else
{
   threadA.start();
   threadAButton->setText(tr("stop A"));
}
}

void ThreadForm::startOrStopTheadB()
{
if(threadB.isRunning())
{
   threadB.stop();
   threadBButton->setText(tr("start B"));
}
else
{
   threadB.start();
   threadBButton->setText(tr("stop B"));
}
}

void ThreadForm::closeEvent(QCloseEvent *event)
{
threadA.stop();
threadB.stop();
threadA.wait();
threadB.wait();
event->accept();
}

主函数的实现：

#include <qapplication.h>
#include <QTextCodec>
#include "ui_thread.h"

int main(int argc, char *argv[])
{
     QApplication app(argc, argv);
     QTextCodec::setCodecForTr(QTextCodec::codecForName("System"));
     ThreadForm threadform;
     threadform.show();
     return app.exec();
}

要使用线程类需要在生成的.pro文件中加入以下两句

CONFIG +=thread        //告诉qmake 使用这个Qt库的线程版本
win32:CONFIG     +=console   //可以使程序从windows的控制台输出

然后再qmake -t vcapp 就可以生成工程文件了