Qt Creator创建一个用户登录界面

目录

[1 界面设计](#1 界面设计)

[2 代码](#2 代码)

[2.1 登录界面](#2.1 登录界面)

[2.2 注册界面](#2.2 注册界面)

[2.3 登陆后的界面](#2.3 登陆后的界面)

[3 完整资源](#3 完整资源)

---

这里主要记录了如何使用Qt Creator创建一个用户登录界面，能够实现用户的注册和登录功能，注册的用户信息存储在了一个文件之中，在登录时可以比对登录信息和文件存储信息，已确认用户是否存在，如果不存在也可以通过注册功能进行注册。

1 界面设计

主要分为3个界面：登录界面、注册界面、登录后的界面

2 代码

2.1 登录界面

登录界面命名对于文件为widget.h、widget.c

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <form.h>
#include <form01.h>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Form *form = new Form();         // define a object
    Form01 *form01 = new Form01();   // Login

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    void on_pushButton_clicked();

    void on_pushButton_2_clicked();

    void on_pushButton_3_clicked();

private:
    Ui::Widget *ui;
};
#endif // WIDGET_H

widget.c

#include "widget.h"
#include "ui_widget.h"
#include "QDebug"
#include "main.h"
#include "QDir"
#include "QMessageBox"

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

    connect(this->form, &Form::BackSig, this, [=](){
       this->form->hide();
       this->show();
    });

}

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


void Widget::on_pushButton_clicked()
{
    // this->hide();
    // this->close();
    qDebug() << "Change page to Login";

    // gain context about lineEdit and judge and ...
    QString path = QDir::currentPath(); // 获取当前工程所在路径

    std::string user_pwd;  //
    std::string part1;   // useranme
    std::string part2;   // password
    int flag = 1;

    std::ifstream infile("/root/QT_developer/File/user_table.txt");
        if (!infile.is_open()) {
            std::cerr << "Unable to open file!" << std::endl;
        }//

    std::string line;

    QString In_username = ui->lineEdit->text();
    QString In_password = ui->lineEdit_2->text();
    part1 = In_username.toStdString();
    part2 = In_password.toStdString();
    user_pwd = part1 + ":" + part2;

    if(In_password.isEmpty())
    {
        QMessageBox::information(this, "Tips", "In_password is empty!");
    }else if(In_username.isEmpty())
    {
        QMessageBox::information(this, "Tips", "In_usename is empty!");
    }else
    {
        while (std::getline(infile, line)) {  // gain data on a line
            if(user_pwd == line)
            {
                flag = 0;
                infile.close();
                this->close();

                ui->lineEdit->clear();
                ui->lineEdit_2->clear();
                QMessageBox::information(this, "Tips", "Login success!");
                In_username.clear();
                In_password.clear();
                form01->show();
                break;
            }
        }
        if(flag == 1)
        {
            ui->lineEdit->clear();
            ui->lineEdit_2->clear();
            QMessageBox::information(this, "Tips", "username or password is error!");
            In_username.clear();
            In_password.clear();
        }
    }
}

void Widget::on_pushButton_2_clicked()
{
    // this->hide();
    // this->close();
    qDebug() << "Change page to Register";
    form->show();
}

void Widget::on_pushButton_3_clicked()
{
    this->close();
    qDebug() << "Quit";
}

2.2 注册界面

注册界面命名对于文件为form.h、form.c

form.h

#ifndef FORM_H
#define FORM_H

#include <QWidget>

namespace Ui {
class Form;
}

class Form : public QWidget
{
    Q_OBJECT

public:
    explicit Form(QWidget *parent = nullptr);
    ~Form();

public:
    void Open_file();

private slots:
    void on_pushButton_2_clicked();

    void on_pushButton_clicked();

private:
    Ui::Form *ui;

signals:
    void BackSig();  // define a signal without arg.
};

#endif // FORM_H

form.c

#include "form.h"
#include "ui_form.h"
#include "qdebug.h"
#include "widget.h"
#include "QLineEdit"
#include "QMessageBox"
#include "main.h"
#include "QDir"

Form::Form(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form)
{
    ui->setupUi(this);
    // this->show();

}

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

void Form::on_pushButton_2_clicked()
{
    qDebug() << "Back";
    emit this->BackSig();

}

void Form::on_pushButton_clicked()
{
    ///

    QString path = QDir::currentPath(); // 获取当前工程所在路径
    std::size_t found; // 查找冒号的位置
    std::string user_pwd;  // Concatenated username and password
    std::string part1;   // useranme
    std::string part2;   // password
    std::string line;
    int flag = 1;

    std::ofstream outfile; // ready for writing

    // std::ifstream infile(path.toStdString() + "user_table.txt");
    std::ifstream infile("/root/QT_developer/File/user_table.txt");  // Absolute path
        if (!infile.is_open()) {              // Determine whether the opening is successful
            std::cerr << "Unable to open file!" << std::endl;
        }


    ///
    // gain data
    QString username = ui->lineEdit->text();
    QString password = ui->lineEdit_2->text();
    QString password_firm = ui->lineEdit_3->text();

    // pan duan yong hu ming shi fou chong fu
    if(username.isEmpty())
    {
        qDebug() << "username can't is empty";
        QMessageBox::information(this, "Tips", "username can't is empty");
    }else if(password.isEmpty()){
        QMessageBox::information(this, "Tips", "password can't is empty");
    }else if(password_firm.isEmpty())
    {
        QMessageBox::information(this, "Tips", "password_firm can't is empty");
    }else{
        // judge
        if(password != password_firm)
        {
            ui->lineEdit->clear();  // clear
            ui->lineEdit_2->clear();
            ui->lineEdit_3->clear();
            QMessageBox::information(this, "Tips", "password != password_firm!");
            username.clear();    // clear
            password.clear();
            password_firm.clear();

        }else{
            while (std::getline(infile, line)) {  // gain data on a line
                found = line.find(':');   // find :
                if (found != std::string::npos) {
                    part1 = line.substr(0, found); // 从开始到冒号前的部分
                    qDebug() << "part1-username: ";
                    cout << "part1-username: " << part1;
                }
                //
                if(QString::fromStdString(part1) == username)
                {
                    flag = 0;
                    infile.close();

                    ui->lineEdit->clear();
                    ui->lineEdit_2->clear();
                    ui->lineEdit_3->clear();
                    QMessageBox::information(this, "Tips", "username has been exist!");
                    username.clear();
                    password.clear();
                    password_firm.clear();
                    break;
                }
            }
            if(flag == 1){
                QMessageBox::information(this, "Tips", "Register success!");
                part1 = username.toStdString();
                part2 = password.toStdString();
                user_pwd = part1 + ":" + part2;
                outfile.open("/root/QT_developer/File/user_table.txt", ios::in | std::ios::out | std::ios::app);
                outfile << user_pwd << endl;
                outfile.close();

                ui->lineEdit->clear();
                ui->lineEdit_2->clear();
                ui->lineEdit_3->clear();
                username.clear();
                password.clear();
                password_firm.clear();
            }


        }
    }



}

2.3 登陆后的界面

登录后的界面命名对于文件为form01.h、form01.c

form01.h

#ifndef FORM01_H
#define FORM01_H

#include <QWidget>

namespace Ui {
class Form01;
}

class Form01 : public QWidget
{
    Q_OBJECT

public:
    explicit Form01(QWidget *parent = nullptr);
    ~Form01();

private:
    Ui::Form01 *ui;
};

#endif // FORM01_H

form01.c

#include "form01.h"
#include "ui_form01.h"

Form01::Form01(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form01)
{
    ui->setupUi(this);
}

Form01::~Form01()
{
    delete ui;
}

3 完整资源

按照以上代码就能实现，如果有需要这是完整代码。也可以私我。

https://download.csdn.net/download/qq_51458770/89492862