Qt多线程的学习--创建一个简单的线程

环境:VS2008+Qt4.7

创建线程流程

1.创建子类继承QThread类

创建子类时不要勾选ui界面

#ifndef MYTHREAD_H
#define MYTHREAD_H

#include <QThread>
#include <QString>

class MyThread : public QThread
{
   Q_OBJECT

public:
   MyThread();
   ~MyThread();
   void threadclose();//关闭线程函数

protected:
   virtual void run();

signals:
   void sendMsg(QString);//自定义信号,用于与主界面通信

private:
   volatile bool stopped;//编写多线程的程序时，同一个变量可能被多个线程修改，而程序通过该变量同步各个线程
};

#endif // MYTHREAD_H

2.重写run函数

//QThread中的run函数是虚函数,线程中需要运行的所有复杂逻辑都在run函数里面执行
void MyThread::run()
{
   while(1)
   {
   		//逻辑代码...
   }
}//与槽函数不一样的地方是run()函数中可以有死循环

3.需要创建线程的时候就实例化子类对象

MyThread thread1 = new MyThread();

4.运行线程

调用start()函数就会执行run()函数中的语句

thread1->start();

5.结束进程

run()中语句return

void MyThread::run()
{
	while(1)
	 	return;//结束线程
}

或者使用QThread::terminate()[slot]

connect(ui->pushButton,SIGNAL(clicked()),thread1,SLOT(terminate()));
//绑定信号和槽,点击按钮结束线程

线程与主界面的通信

Qt中线程间的通信有两种,一种是使用信号和槽机制通信,另一种是共享内存通信 本例使用的是第一种通信方式

线程类中自定义信号

signals:
	void sendMsg(QString);//自定义信号,用于与主界面通信

主窗口类中构造函数添加

	QObject::connect(thread1, SIGNAL(sendMsg(QString)), this, SLOT(recv_msg(QString)));

例子(线程不断发送字符串,主界面把线程发送的字符串显示到textEdit中):

void MyThread::run()
{
	while(1)
	{
		if(stopped == true)
		{
			stopped = false;
			return;
		}
		emit sendMsg("i love Lpx");
		sleep(1);
	}
}

void MyWidget::recv_msg(QString msg)
{
	ui.textEdit->append(msg);
}

参考自 https://blog.youkuaiyun.com/hebbely/article/details/79428336?ops_request_misc=&request_id=&biz_id=102&utm_term=qt%E7%BA%BF%E7%A8%8B%E9%97%B4%E9%80%9A%E4%BF%A1%E6%96%B9%E5%BC%8F&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduweb~default-0-79428336.first_rank_v2_pc_rank_v29&spm=1018.2226.3001.4187

实例源码

/*mythread.h*/
#ifndef MYTHREAD_H
#define MYTHREAD_H

#include <QThread>
#include <QString>

class MyThread : public QThread
{
   Q_OBJECT

public:
   MyThread();
   ~MyThread();
   void threadclose();
protected:
   virtual void run();
signals:
   void sendMsg(QString);
private:
   volatile bool stopped;
};

/*mythread.cpp*/
#include "mythread.h"
#include <cstdlib>
#include <QDebug>

MyThread::MyThread()
{
	stopped = false;
}

MyThread::~MyThread()
{
}

void MyThread::run()
{
	while(1)
	{
		if(stopped == true)
		{
			stopped = false;
			return;
		}
		emit sendMsg("i love Lpx");
		sleep(1);
	}
}

void MyThread::threadclose()
{
	stopped = true;
}

//主窗口类mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H

#include <QtGui/QWidget>
#include "ui_mywidget.h"
#include "mythread.h"
#include <QString>

class MyWidget : public QWidget
{
	Q_OBJECT

public:
	MyWidget(QWidget *parent = 0, Qt::WFlags flags = 0);
	~MyWidget();

public slots:
	void on_pushButton_clicked();
	void recv_msg(QString);
	void on_pushButton_2_clicked();

private:
	Ui::MyWidgetClass ui;
	MyThread *thread1;
};

#endif // MYWIDGET_H

//mywidget.cpp
#include "mywidget.h"

MyWidget::MyWidget(QWidget *parent, Qt::WFlags flags)
	: QWidget(parent, flags)
{
	ui.setupUi(this);
	thread1 = new MyThread();
	QObject::connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(on_pushButton_clicked()));
	QObject::connect(ui.pushButton_2, SIGNAL(clicked()), this, SLOT(on_pushButton_2_clicked()));
	QObject::connect(thread1, SIGNAL(sendMsg(QString)), this, SLOT(recv_msg(QString)));
}

MyWidget::~MyWidget()
{
	delete thread1;
}

void MyWidget::on_pushButton_clicked()
{
	thread1->start();
}

void MyWidget::recv_msg(QString msg)
{
	ui.textEdit->append(msg);
}

void MyWidget::on_pushButton_2_clicked()
{
	thread1->threadclose();
}

实现效果