public class Product {

    private String title;
    private String description;
    private Integer price;
    private String image;
    private Integer id;
    private String category;

    private String HOST = "jdbc:postgresql://localhost:5432/online_shop";
    private String userName = "postgres";
    private String password = "12345";
    private Connection connection;

    public Product() {
        title = "";
        description = "";
        price = 0;
        image = "";
        id = 0;
        category = "";
    }

    public Product(final Integer id, final String title, final String description, final Integer price, final String category, final String image) {
        this.title = title;
        this.description = description;
        this.price = price;
        this.image = image;
        this.id = id;
        this.category = category;
    }

    public String getImage() {
        return this.image;
    }

    public void setImage(final String image) {
        this.image = image;
    }

    public String getTitle() {
        return this.title;
    }

    public void setTitle(final String title) {
        this.title = title;
    }

    public String getDescription() {
        return this.description;
    }

    public void setDescription(final String description) {
        this.description = description;
    }

    public Integer getPrice() {
        return this.price;
    }

    public void setPrice(final Integer price) {
        this.price = price;
    }

    public Integer getId() {
        return this.id;
    }

    public void setId(final Integer id) {
        this.id = id;
    }

    public String getCategory() {return this.category;}

    public void setCategory(final String category) {this.category = category;}

    public ArrayList<Product> getProduct() {
        ArrayList<Product> products = new ArrayList<>();
        try{
            connection = DriverManager.getConnection(HOST, userName, password);
            Statement statement = connection.createStatement();
            ResultSet rs = statement.executeQuery("SELECT *FROM public.\"Product\"");
            while (rs.next()) {
                int id = rs.getInt("id_prod");
                String title = rs.getString("title");
                String description = rs.getString("description");
                int price = rs.getInt("price");
                String category = rs.getString("category");
                String img = rs.getString("img");
                Product prod = new Product(id, title, description, price, category, img);
                products.add(prod);
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        return products;
    }

@Controller
public class Home {
    @RequestMapping("/")
    public String homeWithSession(Model model, HttpSession session) {
        Product product = new Product();
        String sid = session.getId();
        model.addAttribute("sid", sid);
        ArrayList<Product> products = product.getProduct();
        model.addAttribute("products", products);
        return "index"; }}

<section class="main-content">
    <div class="container">
        <div class="row">
            <div class="col-lg-3 col-sm-6 mb-3" th:each="product : ${products}">
                <div class="card" style="width: 18rem;">
                    <img class="card-img-top" th:src="${product.image}" alt="Card image cap">
                    <div class="card-body">
                        <h5 class="card-title" th:text="${product.title}"></h5>
                        <p class="card-text" th:text="${product.description}"></p>
                        <div class="price">
                            <p th:text="${product.price}"></p>
                            <p>руб.</p>
                        </div>
                        <button class="btn btn-dark cart" th:data-id="${product.id}">В корзину</button>
                    </div>
                </div>
            </div>
        </div>
    </div>
</section>