1.QSqlQuery的增删改查

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QSqlQueryModel>
#include <QTableView>
#include <QLineEdit>
#include <QSpinBox>
#include <QPushButton>
#include <QVBoxLayout>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow {
    Q_OBJECT

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

private slots:
    void on_addButton_clicked();
    void on_deleteButton_clicked();
    void on_updateButton_clicked();
    void on_loadButton_clicked();

private:
    QLineEdit *nameLineEdit;
    QLineEdit *genderLineEdit;
    QSpinBox *ageSpinBox;
    QSpinBox *scoreSpinBox;
    QPushButton *addButton;
    QPushButton *deleteButton;
    QPushButton *updateButton;
    QTableView *tableView;
    QSqlQueryModel *model;

    void loadData();
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "MainWindow.h"
#include <QSqlQuery>
#include <QSqlError>
#include <QMessageBox>
#include <QSqlError>


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent) {
    // 创建控件
    nameLineEdit = new QLineEdit(this);
    genderLineEdit = new QLineEdit(this);
    ageSpinBox = new QSpinBox(this);
    scoreSpinBox = new QSpinBox(this);
    addButton = new QPushButton("添加", this);
    deleteButton = new QPushButton("删除", this);
    updateButton = new QPushButton("更新", this);

    tableView = new QTableView(this);

    // 设置 SpinBox 范围
    ageSpinBox->setRange(0, 150);
    scoreSpinBox->setRange(0, 100);

    // 布局
    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(nameLineEdit);
    layout->addWidget(genderLineEdit);
    layout->addWidget(ageSpinBox);
    layout->addWidget(scoreSpinBox);
    layout->addWidget(addButton);
    layout->addWidget(deleteButton);
    layout->addWidget(updateButton);
    layout->addWidget(tableView);

    QWidget *widget = new QWidget(this);
    widget->setLayout(layout);
    setCentralWidget(widget);

    // 连接按钮信号与槽
    connect(addButton, &QPushButton::clicked, this, &MainWindow::on_addButton_clicked);
    connect(deleteButton, &QPushButton::clicked, this, &MainWindow::on_deleteButton_clicked);
    connect(updateButton, &QPushButton::clicked, this, &MainWindow::on_updateButton_clicked);
    // 初始化模型和视图
    model = new QSqlQueryModel(this);
    loadData();
}

MainWindow::~MainWindow() {
}

void MainWindow::loadData() {
    model->setQuery("SELECT * FROM students");
    tableView->setModel(model);
}

void MainWindow::on_addButton_clicked() {
    QString name = nameLineEdit->text();
    QString gender = genderLineEdit->text();
    int age = ageSpinBox->value();
    double score = scoreSpinBox->value();

    QSqlQuery query;
    query.prepare("INSERT INTO students (name, gender, age, score) VALUES (?, ?, ?, ?)");
    query.addBindValue(name);
    query.addBindValue(gender);
    query.addBindValue(age);
    query.addBindValue(score);

    if (!query.exec()) {
        QMessageBox::critical(this, "添加失败", query.lastError().text());
    } else {
        loadData();
    }
}

void MainWindow::on_deleteButton_clicked() {
    QString name = nameLineEdit->text();
    QSqlQuery query;
    query.prepare("DELETE FROM students WHERE name = ?");
    query.addBindValue(name);

    if (!query.exec()) {
        QMessageBox::critical(this, "删除失败", query.lastError().text());
    } else {
        loadData();
    }
}

void MainWindow::on_updateButton_clicked() {
    QString name = nameLineEdit->text();
    QString gender = genderLineEdit->text();
    int age = ageSpinBox->value();
    double score = scoreSpinBox->value();

    QSqlQuery query;
    query.prepare("UPDATE students SET gender = ?, age = ?, score = ? WHERE name = ?");
    query.addBindValue(gender);
    query.addBindValue(age);
    query.addBindValue(score);
    query.addBindValue(name);

    if (!query.exec()) {
        QMessageBox::critical(this, "更新失败", query.lastError().text());
    } else {
        loadData();
    }
}

void MainWindow::on_loadButton_clicked() {
    loadData();
}

main.cpp

#include <QApplication>
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QMessageBox>
#include <QSqlError>
#include "MainWindow.h"

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

    // 设置数据库连接
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("students.db");

    if (!db.open()) {
        QMessageBox::critical(nullptr, "Database Error", db.lastError().text());
        return -1;
    }

    // 创建表
    QSqlQuery query;
    query.exec("CREATE TABLE IF NOT EXISTS students (name TEXT, gender TEXT, age INTEGER, score REAL)");

    MainWindow window;
    window.show();

    return app.exec();
}

人脸识别

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTimer>
#include <opencv2/opencv.hpp>

using namespace cv;

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    void processFrameAndUpdateGUI();

private:
    Ui::MainWindow *ui;
    VideoCapture cap;  // 摄像头捕获
    QTimer *timer;     // 定时器用于更新图像
    CascadeClassifier faceCascade; // 用于人脸检测的分类器

    void detectAndDraw(Mat &frame);
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QMessageBox>
#include <QImage>
#include <QPixmap>
#include <QDir>
#include <qDebug>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
    , timer(new QTimer(this))
{
    ui->setupUi(this);
    // 加载 OpenCV 的人脸检测分类器
    if (!faceCascade.load("haarcascade_frontalface_default.xml")) {
        QMessageBox::critical(this, "Error", "Error loading haarcascade_frontalface_default.xml");
        return;
    }

    // 打开摄像头（0代表默认摄像头）
    if (!cap.open(0)) {
        QMessageBox::critical(this, "Error", "Error opening video camera");
        return;
    }

    // 设置定时器，每33毫秒（约30帧每秒）触发一次
    connect(timer, &QTimer::timeout, this, &MainWindow::processFrameAndUpdateGUI);
    timer->start(33);
}

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

void MainWindow::processFrameAndUpdateGUI()
{
    Mat frame;
    cap >> frame; // 从摄像头捕获当前帧

    if (frame.empty()) {
        return;
    }

    flip(frame, frame, 1); // 镜像翻转
    detectAndDraw(frame);  // 检测人脸并绘制红色矩形框

    // 将 OpenCV 的 Mat 转换为 Qt 的 QImage
    QImage qimg(frame.data, frame.cols, frame.rows, frame.step, QImage::Format_BGR888);

    // 在界面上显示视频流
    ui->label->setPixmap(QPixmap::fromImage(qimg));
    ui->label->resize(qimg.size());
}

void MainWindow::detectAndDraw(Mat &frame)
{
    std::vector<Rect> faces;
    Mat gray;

    // 将彩色图像转换为灰度图像
    cvtColor(frame, gray, COLOR_BGR2GRAY);
    equalizeHist(gray, gray);

    // 检测人脸
    faceCascade.detectMultiScale(gray, faces, 1.1, 3, 0, Size(30, 30));

    // 遍历检测到的所有人脸，并在每张人脸上绘制红色矩形框
    for (size_t i = 0; i < faces.size(); ++i) {
        rectangle(frame, faces[i], Scalar(0, 0, 255), 2); // 绘制红色矩形
    }
}

3,mian.cpp

#include "MainWindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}