Qt实现防止程序多次运行

单例化

可以通过QSharedMemory的特性实现应用程序单例化。

共享内存不能重复创建(Create)

#include <QApplication>
#include <QSharedMemory>
#include <QMessageBox>
#include <QDebug>

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	QSharedMemory sharedMemory("App.exe");

	if (sharedMemory.create(1))
	{
		return a.exec();
	}
	else
	{
		qDebug()<<"Software is running!";
		QMessageBox::information(0, "Clue", "Software is running!");
	}
}

或者

#include <QApplication>
#include <QSharedMemory>
#include <QMessageBox>
#include <QDebug>

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	QSharedMemory *sharedMemory = new QSharedMemory(QString("App.exe"));

	if (sharedMemory->create(1))
	{
		return a.exec();
	}
	else
	{
		qDebug()<<"Software is running!";
		QMessageBox::information(0, "Clue", "Software is running!");
	}

	delete sharedMemory;
	sharedMemory = NULL;
}

共享内存未创建不能Attach

#include <QApplication>
#include <QSharedMemory>
#include <QMessageBox>
#include <QDebug>

int main(int argc, char *argv[])
{
	QSharedMemory shared("App.exe");
	if(shared.attach(QSharedMemory::ReadOnly))//利用attach无法绑定未申请内存空间的特点判断该应用程序是否唯一
	{
		return 0;//结束程序运行
	}
	shared.create(1);//创建共享内存，空间大小为1字节

	QApplication a(argc, argv);
	return a.exec();
}