这个 JavaFX 程序只是允许用户注册用户名和密码，然后将其存储在 SQL 数据库中。

有人批评它不够干净、易读或不可维护，但它似乎仍然有效，所以我希望寻求真正从事软件开发行业的人士而不是高中教师的批评。

public class MainController {
    // region Variables
    @FXML
    private Label formText, welcomeText;
    @FXML
    private Button login, signup;
    @FXML
    private TextField username, email, password, confirmPassword;
    @FXML
    private Button forgotPassword, formButton, resetPasswordButton;
    @FXML
    private AnchorPane formPage, dashboardPage;
    // endregion

    // region Form
    @FXML
    private void ChangeForm() {
        ObservableList<String> shortLogin = login.getStyleClass(), shortSignUp = signup.getStyleClass();
        if (shortLogin.contains("active")) { // switching to signup
            formText.setText("Signup Form");
            shortLogin.remove("active");
            shortLogin.add("notActive");
            shortSignUp.remove("notActive");
            shortSignUp.add("active");
            confirmPassword.setVisible(true);
            formButton.setText("Sign Up");
            forgotPassword.setVisible(false);
        } else /*if (shortSignUp.contains("active"))*/ { // switching to login
            formText.setText("Login Form");
            formButton.setText("Login");
            shortSignUp.remove("active");
            if(!shortSignUp.contains("notActive"))
                shortSignUp.add("notActive");
            shortLogin.remove("notActive");
            shortLogin.add("active");
            confirmPassword.setVisible(false);
            formButton.setText("Login");
            password.setPromptText("Password:");
            forgotPassword.setVisible(true);
        }
        ClearForm();
    }

    @FXML
    private void FormSubmit() {
        if (ValidForm()) {
            try {
                String name = (signup.getStyleClass().contains("active")) ? SQLUtils.Register(username.getText(), password.getText(), email.getText()) : SQLUtils.Login(username.getText(), password.getText(), email.getText());
                formPage.setVisible(false);
                dashboardPage.setVisible(true);
                welcomeText.setText("Welcome, " + name);
                ClearForm();
            } catch (Exception ignored) {
                ErrorAlert(Alert.AlertType.ERROR, "SQL Error", "Error Retrieving SQL Information from MainController", "There was an error retrieving the SQL information, or that user doesn't exist.");
            }
        }
    }
    
    @FXML
    private void Forgot() {
        forgotPassword.setVisible(false);
        resetPasswordButton.setVisible(true);
        forgotPassword.setVisible(true);
        formText.setText("Forgot Password");
        formButton.setVisible(false);
        password.setPromptText("Enter New Password:");
        
        ObservableList<String> shortLogin = login.getStyleClass();
        if(shortLogin.contains("active") && !shortLogin.contains("notActive")) {
            shortLogin.remove("active");
            shortLogin.add("notActive");
        }
    }
    @FXML
    private void ResetPassword() {
        if(ValidForm()) {
            resetPasswordButton.setVisible(false);
            formButton.setVisible(true);
            forgotPassword.setVisible(true);
            formButton.setVisible(true);
            password.setPromptText("Password:");
            
            ObservableList<String> shortLogin = login.getStyleClass();
            formText.setText("Login Form");
            shortLogin.remove("notActive");
            shortLogin.add("active");
            SQLUtils.ResetPassword(username.getText(), password.getText(), email.getText());
            ClearForm();
        }
    }

    // endregion
    // region Utils
    private void ClearForm() {
        username.clear();
        email.clear();
        password.clear();
        confirmPassword.clear();
    }
    
    private boolean ValidForm() {       
        String emailRegex = "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9._]+\\.[a-zA-Z]{2,6}$";
        String passwordRegex = "^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[/~`!@#$%^&*()_+{};:',<.>? =]).{8,}$";

        if (username.getText().isEmpty() || email.getText().isEmpty() || password.getText().isEmpty() || (signup.getStyleClass().contains("active") && confirmPassword.getText().isEmpty())) {
            ErrorAlert(Alert.AlertType.INFORMATION, "Form Validation", "Invalid Fields", "All Fields Must Be Filled In");
            return false;
        } else if (!Pattern.compile(emailRegex).matcher(email.getText()).matches()) {
            ErrorAlert(Alert.AlertType.INFORMATION, "Form Validation", "Invalid Email", "Please Enter A Valid Email That Contains An '@' And A '.com'");
            return false;
        } else if (!Pattern.compile(passwordRegex).matcher(password.getText()).matches()) {
            ErrorAlert(Alert.AlertType.INFORMATION, "Form Validation", "Invalid Password", "Please Enter A Valid Password That Contains At Least 8 Characters, 1 Uppercase, 1 Lowercase, 1 Number, and 1 Special Character");
            return false;
        } else if (signup.getStyleClass().contains("active") && !password.getText().equals(confirmPassword.getText())) {
            ErrorAlert(Alert.AlertType.INFORMATION, "Form Validation", "Passwords Must Match", "Password And Confirm Password Must Match");
            return false;
        } else if (!SQLUtils.ValidInfo(username.getText(), password.getText(), email.getText())) {
            ErrorAlert(Alert.AlertType.ERROR, "Invalid Info", "That User Does Not Exist", "Please enter valid information for a user that does already exist.");
            return false;
        }
        return true;
    }
    public static void ErrorAlert(Alert.AlertType type, String title, String headerText, String contentText) {
        Alert alert = new Alert(type);
        alert.setTitle(title);
        alert.setHeaderText(headerText);
        alert.setContentText(contentText);
        alert.showAndWait();
    }
    @FXML
    private void LogOut() {
        formPage.setVisible(true);
        dashboardPage.setVisible(false);
        welcomeText.setText("Welcome, NAME HERE");
    }

    // endregion
    // region Window Settings
    @FXML
    private void Minimize(ActionEvent event) {
        ((Stage) ((Button) event.getSource()).getScene().getWindow()).setIconified(true);
    }

    @FXML
    private void Close() {
        System.exit(0);
    }

    // endregion
}

public class SQLUtils {
    // region Main Methods
    public static String Login(String username, String password, String email) {
        String sql = "select * from users_table where username = ? and password = ? and email = ?";
        RunSQL(sql, username, password, email, true);
        return username;
    }
    public static String Register(String username, String password, String email) {
        String sql = "insert into users_table (username, password, email) values (?, ?, ?)";
        RunSQL(sql, username, password, email, false);
        return username;
    }
    public static void ResetPassword(String username, String newPassword, String email) {
        String sql = "update users_table set password=? where username=? and email=?;";
        RunSQL(sql, newPassword, username, email, false);
    }
    // endregion
    // region Utils
    private static Connection ConnectDB() {
        try {
            return DriverManager.getConnection("jdbc:mysql://localhost:3306/login_and_register", "root", "password");
        } catch (Exception ignored) {
            MainController.ErrorAlert(Alert.AlertType.ERROR, "SQL Error", "Error Retrieving SQL Information", "Information could not be retrieved");
        }
        return null;
    }
    public static boolean ValidInfo(String username, String password, String email) {
        String sql = "select * from users_table where username = ? and password = ? and email = ?";
        Connection connect = ConnectDB();
        if (connect == null)
            return false;
        
        try (PreparedStatement prepared = connect.prepareStatement(sql)) {
            prepared.setString(1, username);
            prepared.setString(2, password);
            prepared.setString(3, email);
            prepared.executeQuery();
            System.out.println("working");
            // FORM ALWAYS RESULTS IN WORKING, EVEN WHEN USER IS INVALID, DOES NOT ADD TO TABLE THO
            return true;
        } catch (Exception ignored) {
            MainController.ErrorAlert(Alert.AlertType.ERROR, "Error", "Error Running SQL", "There was an error running the SQL information, or that user doesn't exist.");
        }
        System.out.println("not working");
        return false;
    }
    private static void RunSQL(String sql, String username, String password, String email, boolean query) {
        Connection connect = ConnectDB();
        if (connect == null)
            return;
        
        try (PreparedStatement prepared = connect.prepareStatement(sql)) {
            prepared.setString(1, username);
            prepared.setString(2, password);
            prepared.setString(3, email);
            if (query)
                prepared.executeQuery();
            else
                prepared.executeUpdate();
        } catch (SQLException ignored) {
            MainController.ErrorAlert(Alert.AlertType.ERROR, "SQL Error", "Error Retrieving SQL Information, from RUNSQL", "There was an error retrieving the SQL information.");
        } catch (Exception ignored) {
            MainController.ErrorAlert(Alert.AlertType.ERROR, "Error", "Error Running SQL", "There was an error running the SQL information, or that user doesn't exist.");
        }
    }
    // endregion
}