qtSingleApplication使用总结-CSDN博客
示例：
cpp
#include "mainwindow.h"
#include <QApplication>
#include <QMessageBox>
#include "qtsingleapplication/qtsingleapplication.h"
int main(int argc, char *argv[])
{
QtSingleApplication singleApp("test",argc,argv);
if(singleApp.isRunning())
{
QMessageBox::information(nullptr,"提示","程序已运行！","确定");
return -1;
}
MainWindow w;
w.show();
return singleApp.exec();
}