基于QT，写一个车辆信息管理系统的代码。每台车辆至少需要包含以下属性，系统中保存多台车辆的信息：车辆型号,厂商,车型级别,座位数,排量,变速箱,车身颜色,价格。能够浏览所有车辆信息：统计共有多少台车辆，并在界面上显示所有车辆信息；按照厂商查询车所有属于该厂商的车辆信息。

以下是基于QT的车辆信息管理系统代码。

mainwindow.h文件

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QStandardItemModel>

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_btnAdd_clicked();

    void on_btnDelete_clicked();

    void on_btnSearch_clicked();

private:
    Ui::MainWindow *ui;
    QStandardItemModel *model;
    void loadData();
};

#endif // MAINWINDOW_H

mainwindow.cpp文件

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QStandardItemModel>
#include <QMessageBox>

struct Car {
    QString type;
    QString manufacturer;
    QString level;
    int seats;
    double displacement;
    QString transmission;
    QString color;
    double price;
};

QList<Car> cars;

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

    // 设置表格头
    model = new QStandardItemModel(this);
    model->setColumnCount(8);
    model->setHeaderData(0, Qt::Horizontal, "车辆型号");
    model->setHeaderData(1, Qt::Horizontal, "厂商");
    model->setHeaderData(2, Qt::Horizontal, "车型级别");
    model->setHeaderData(3, Qt::Horizontal, "座位数");
    model->setHeaderData(4, Qt::Horizontal, "排量");
    model->setHeaderData(5, Qt::Horizontal, "变速箱");
    model->setHeaderData(6, Qt::Horizontal, "车身颜色");
    model->setHeaderData(7, Qt::Horizontal, "价格");

    ui->tableView->setModel(model);

    // 加载数据
    loadData();
}

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

void MainWindow::loadData()
{
    // 模拟数据
    cars.clear();
    cars.append({"ModelA", "ManufacturerA", "LevelA", 5, 2.0, "Auto", "Red", 100000.0});
    cars.append({"ModelB", "ManufacturerB", "LevelB", 7, 3.0, "Manual", "Black", 150000.0});
    cars.append({"ModelC", "ManufacturerA", "LevelB", 5, 2.5, "Auto", "White", 120000.0});

    // 显示数据
    model->removeRows(0, model->rowCount());
    for (int i = 0; i < cars.size(); i++) {
        const Car &car = cars.at(i);
        QList<QStandardItem*> rowItems;
        rowItems.append(new QStandardItem(car.type));
        rowItems.append(new QStandardItem(car.manufacturer));
        rowItems.append(new QStandardItem(car.level));
        rowItems.append(new QStandardItem(QString::number(car.seats)));
        rowItems.append(new QStandardItem(QString::number(car.displacement)));
        rowItems.append(new QStandardItem(car.transmission));
        rowItems.append(new QStandardItem(car.color));
        rowItems.append(new QStandardItem(QString::number(car.price)));
        model->appendRow(rowItems);
    }

    // 显示车辆数量
    ui->lblCount->setText(QString("共 %1 辆车").arg(cars.size()));
}

void MainWindow::on_btnAdd_clicked()
{
    // 打开添加对话框
    QString type = QInputDialog::getText(this, "添加车辆", "请输入车辆型号");
    if (type.isEmpty()) {
        return;
    }

    QString manufacturer = QInputDialog::getText(this, "添加车辆", "请输入厂商");
    if (manufacturer.isEmpty()) {
        return;
    }

    QString level = QInputDialog::getText(this, "添加车辆", "请输入车型级别");
    if (level.isEmpty()) {
        return;
    }

    bool ok;
    int seats = QInputDialog::getInt(this, "添加车辆", "请输入座位数", 0, 0, 100, 1, &ok);
    if (!ok) {
        return;
    }

    double displacement = QInputDialog::getDouble(this, "添加车辆", "请输入排量", 0.0, 0.0, 100.0, 1, &ok);
    if (!ok) {
        return;
    }

    QString transmission = QInputDialog::getText(this, "添加车辆", "请输入变速箱");
    if (transmission.isEmpty()) {
        return;
    }

    QString color = QInputDialog::getText(this, "添加车辆", "请输入车身颜色");
    if (color.isEmpty()) {
        return;
    }

    double price = QInputDialog::getDouble(this, "添加车辆", "请输入价格", 0.0, 0.0, 10000000.0, 1, &ok);
    if (!ok) {
        return;
    }

    // 添加到列表
    cars.append({type, manufacturer, level, seats, displacement, transmission, color, price});

    // 显示到界面
    QList<QStandardItem*> rowItems;
    rowItems.append(new QStandardItem(type));
    rowItems.append(new QStandardItem(manufacturer));
    rowItems.append(new QStandardItem(level));
    rowItems.append(new QStandardItem(QString::number(seats)));
    rowItems.append(new QStandardItem(QString::number(displacement)));
    rowItems.append(new QStandardItem(transmission));
    rowItems.append(new QStandardItem(color));
    rowItems.append(new QStandardItem(QString::number(price)));
    model->appendRow(rowItems);

    // 显示车辆数量
    ui->lblCount->setText(QString("共 %1 辆车").arg(cars.size()));
}

void MainWindow::on_btnDelete_clicked()
{
    // 获取选中的行
    QModelIndexList indexes = ui->tableView->selectionModel()->selectedRows();
    if (indexes.isEmpty()) {
        QMessageBox::warning(this, "删除车辆", "请先选中要删除的车辆");
        return;
    }

    // 删除行
    int row = indexes.first().row();
    cars.removeAt(row);
    model->removeRow(row);

    // 显示车辆数量
    ui->lblCount->setText(QString("共 %1 辆车").arg(cars.size()));
}

void MainWindow::on_btnSearch_clicked()
{
    // 打开查询对话框
    QString manufacturer = QInputDialog::getText(this, "查询车辆", "请输入厂商");
    if (manufacturer.isEmpty()) {
        return;
    }

    // 查询车辆
    QList<Car> filteredCars;
    for (int i = 0; i < cars.size(); i++) {
        const Car &car = cars.at(i);
        if (car.manufacturer == manufacturer) {
            filteredCars.append(car);
        }
    }

    // 显示查询结果
    model->removeRows(0, model->rowCount());
    for (int i = 0; i < filteredCars.size(); i++) {
        const Car &car = filteredCars.at(i);
        QList<QStandardItem*> rowItems;
        rowItems.append(new QStandardItem(car.type));
        rowItems.append(new QStandardItem(car.manufacturer));
        rowItems.append(new QStandardItem(car.level));
        rowItems.append(new QStandardItem(QString::number(car.seats)));
        rowItems.append(new QStandardItem(QString::number(car.displacement)));
        rowItems.append(new QStandardItem(car.transmission));
        rowItems.append(new QStandardItem(car.color));
        rowItems.append(new QStandardItem(QString::number(car.price)));
        model->appendRow(rowItems);
    }

    // 显示车辆数量
    ui->lblCount->setText(QString("共 %1 辆车").arg(filteredCars.size()));
}

使用QStandardItemModel作为数据模型，实现了添加、删除、查询等功能。其中，loadData()函数用于加载模拟数据，on_btnAdd_clicked()函数用于打开添加对话框并添加一条车辆信息，on_btnDelete_clicked()函数用于删除选中的车辆信息，on_btnSearch_clicked()函数用于打开查询对话框并查询属于指定厂商的车辆信息。