【Qt】一个简单的C++单例模式示例

单例类Test

#pragma once
#include <qwidget.h>
class Test :
    public QWidget
{
public:
    static Test& instance()
    {
        static Test test;
        return test;
    }
    void set(int a, int b)
    {
        c = a;
        d = b;
    }
    void get(int& a, int& b)
    {
        a = c;
        b = d;
    }
private:
	int c=0;
    int d=0;
    Test() {}
    Test(const Test&) {}
    Test& operator==(const Test&) {}
};

SingleInstance单例类

#pragma once

#include <QtWidgets/QMainWindow>
#include "ui_SingleInstance.h"

class SingleInstance : public QMainWindow
{
    Q_OBJECT

public:
    SingleInstance(QWidget *parent = Q_NULLPTR);
    static SingleInstance& instance()
    {
        static SingleInstance qinstance;
        return qinstance;
    }
private:
    Ui::SingleInstanceClass ui;
};

main.cpp

#include "SingleInstance.h"
#include <QtWidgets/QApplication>
#include "Test.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Test::instance().set(3,5);//此处将Test类中的c、d设置为3、5
    SingleInstance::instance().show();
    return a.exec();
}

SingleInstance.cpp

#include "SingleInstance.h"
#include <qpushbutton.h>
#include "Test.h"
#include <qmessagebox.h>
#include <qdebug.h>

SingleInstance::SingleInstance(QWidget *parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);
    int a=0, b=0;
    Test::instance().get(a,b);
    qDebug() << "a:" << a << " b:" << b << endl;//此处打印3,5
}