01.10

?main.c

#include "widget.h"
#include <QApplication>
#include "success.h"
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    success s;
    QObject::connect(&w,&Widget::login_signal,&s,&success::login_slot);
    return a.exec();
}

?登录界面

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include<QDebug>
#include<QMessageBox>
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = nullptr);
    ~Widget();
public slots:
    void Cancelbtn();
    void Loginbtn();
signals:
    void login_signal();
private:
    Ui::Widget *ui;
};

#endif // WIDGET_H

?widget.cpp

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->userlab->setPixmap(QPixmap(":/pictrue/userName.jpg"));
    ui->userlab->setScaledContents(true);
    ui->passwdlab->setPixmap(QPixmap(":/pictrue/passwd.jpg"));
    ui->passwdlab->setScaledContents(true);
    ui->passwdedit->setEchoMode(QLineEdit::Password);
    //将取消按钮使用qt4版本的连接到自定义的槽函数中
    connect(ui->cancelbtn,SIGNAL(clicked()),this,SLOT(Cancelbtn()));
    //将登录按钮使用qt5版本的连接到自定义的槽函数中
    connect(ui->loginbtn,&QPushButton::clicked,this,&Widget::Loginbtn);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::Cancelbtn()
{
    //弹出一个问题对话框
    int ret=QMessageBox::question(this,"问题","您是否确定要退出登录？",QMessageBox::Yes|QMessageBox::No);
    if(ret==QMessageBox::Yes)
    {
        //Yes后，关闭登录界面
        close();
    }else
    {
        //No后，关闭对话框
        this->show();
    }
}

void Widget::Loginbtn()
{
    //在槽函数中判断ui界面上输入的账号是否为"admin"，密码是否为"123456"
    if(ui->useredit->text()=="admin"&ui->passwdedit->text()=="123456")
    {
        //登录成功
        qDebug()<<"登陆成功"<<endl;
        close();
        //基于静态成员函数版本的对话框
        int ret=QMessageBox::information(this,"提示","登陆成功",QMessageBox::Ok);
        //点击ok转到下一个界面
        if(ret==QMessageBox::Ok)
        {
            emit login_signal();
        }
    }else
    {
        //登录失败
        qDebug()<<"登录失败"<<endl;
        //基于属性版本的错误提示框
        //1.用该类实例化一个对象
        QMessageBox miss_msg(QMessageBox::Critical,
                    "错误",
                    "账号和密码不匹配，是否重新登录",
                    QMessageBox::Yes|QMessageBox::No,
                    this);
        //2.需要调用exec()弹出对话框
        int ret=miss_msg.exec();

        if(ret==QMessageBox::Yes)
        {
            //点击yes清除密码框中的内容
           ui->passwdedit->clear();
        }else
        {
            //点击No按钮，则直接关闭登录界面
            close();
        }
    }

}

?登录成功跳转页面

success.h

#ifndef SUCCESS_H
#define SUCCESS_H

#include <QWidget>

namespace Ui {
class success;
}

class success : public QWidget
{
    Q_OBJECT

public:
    explicit success(QWidget *parent = nullptr);
    ~success();
public slots:
    void login_slot();
private:
    Ui::success *ui;
};

#endif // SUCCESS_H

success.cpp?

#include "success.h"
#include "ui_success.h"

success::success(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::success)
{
    ui->setupUi(this);
}

success::~success()
{
    delete ui;
}

void success::login_slot()
{
    this->show();
}