mvc中的数据库查询语句

// Model层
public class User {
    private int id;
    private String name;
    private String email;

    // Getters and setters
}

public class UserModel {
    private Connection connection;

    public UserModel(Connection connection) {
        this.connection = connection;
    }

    public List<User> getAllUsers() throws SQLException {
        List<User> users = new ArrayList<>();
        String sql = "SELECT id, name, email FROM users";
        try (PreparedStatement stmt = connection.prepareStatement(sql);
             ResultSet rs = stmt.executeQuery()) {
            while (rs.next()) {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setEmail(rs.getString("email"));
                users.add(user);
            }
        }
        return users;
    }
}

// Controller层
public class UserController {
    private UserModel userModel;

    public UserController(UserModel userModel) {
        this.userModel = userModel;
    }

    public List<User> getAllUsers() {
        try {
            return userModel.getAllUsers();
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }
}

// View层
public class UserView {
    private UserController userController;

    public UserView(UserController userController) {
        this.userController = userController;
    }

    public void displayUsers() {
        List<User> users = userController.getAllUsers();
        if (users != null) {
            for (User user : users) {
                System.out.println("ID: " + user.getId() + ", Name: " + user.getName() + ", Email: " + user.getEmail());
            }
        } else {
            System.out.println("Failed to retrieve users.");
        }
    }
}