JDBC连接无法从数据库JAVAFX Application获取结果

Question

我在netbeans中创建了一个简单的JAVAFX应用程序。用户可以登录和搜索员工详细信息。但问题是，在创建JDBC连接并从应用程序单击提交按钮后，我无法获取任何结果。我已经独立测试了JDBC连接并且它工作正常，但它在JAVAFX应用程序中不起作用。 这是我的JDBC连接代码：

private static Connection conn;
private static Statement stmt;
private static String url = "jdbc:mysql://localhost/EmpAttendance";
private static String user = "root";//Username of database  
private static String pass = "root";//Password of database

public static Connection connect() {
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection(url, user, pass);
        stmt = conn.createStatement();
        String sql;
        sql = "SELECT * FROM EmpAttendance.emp_attendance;";
        ResultSet rs = stmt.executeQuery(sql);

        while (rs.next()) {
            System.out.println(rs.getString("trans_id"));
        }
        rs.close();
        stmt.close();
        conn.close();
    } catch (ClassNotFoundException | SQLException ex) {
        Logger.getLogger(JDBCDemo.class.getName()).log(Level.SEVERE, null, ex);
    }
    return conn;
}

这是我的JAVAFX应用程序代码：

Scene scene, scene2;
Connection c;


@Override
public void start(Stage stage) throws Exception {


    //login layout
    StackPane root1 = new StackPane();

    //employee ids addition layout
    StackPane root2 = new StackPane();

    VBox scene2Box = secondScene();

    VBox formLayout = firstScene(stage);

    //Adding form layout to the root layout
    root1.getChildren().addAll(formLayout);

    //Adding second scene to add employees
    root2.getChildren().addAll(scene2Box);


    //adding login scene to the stage
    scene = new Scene(root1, 500, 250);
    //adding employee id screen to the stage
    scene2 = new Scene(root2, 500, 250);
    stage.setTitle("My window");
    stage.setScene(scene);
    stage.show();
}

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    launch(args);

}

private VBox secondScene() {
    TextField field = new TextField();

    HBox box = new HBox();
    VBox mainBox = new VBox();
    ListView<String> myview = new ListView<>();
    Button submit = new Button();
    submit.setText("Submit");
    Button addBtn = new Button();
    addBtn.setText("Add");
    addBtn.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            if (!field.getText().trim().isEmpty()) {
                System.out.println(field.getText());
                myview.getItems().add(field.getText());
            } else {
                Alert alert = new Alert(AlertType.WARNING, "Please enter Employee ID ", ButtonType.OK);
                alert.showAndWait();
            }
        }
    });

    submit.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {
            if(!myview.getItems().isEmpty()){
                c = JDBCDemo.connect();
            }else{
                Alert alert = new Alert(AlertType.WARNING, "Please enter atleast one Employee ID ", ButtonType.OK);
                alert.showAndWait();
            }
        }
    });

    box.getChildren().addAll(field, addBtn);
    HBox.setHgrow(field, Priority.ALWAYS);
    mainBox.getChildren().addAll(box, myview,submit);
    return mainBox;
}

private VBox firstScene(Stage stage){
    //Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));
    ReadOnlyStringWrapper empIdText = new ReadOnlyStringWrapper("Employee ID");
    ReadOnlyStringProperty readOnlyEmpId = empIdText.getReadOnlyProperty();

    ReadOnlyStringWrapper passText = new ReadOnlyStringWrapper("Password");
    ReadOnlyStringProperty readOnlyPassword = passText.getReadOnlyProperty();

    ReadOnlyStringWrapper submitText = new ReadOnlyStringWrapper("Submit");
    ReadOnlyStringProperty readOnlySubmit = submitText.getReadOnlyProperty();

    //'employee ID' text
    Label empIdfield = new Label();
    empIdfield.textProperty().bind(readOnlyEmpId);

    //Text Field to insert employee id
    TextField employeeid = new TextField();
    employeeid.setPromptText("Employee ID");

    //'Password' text
    Label passwordField = new Label();
    passwordField.textProperty().bind(readOnlyPassword);

    //Password Field to enter password
    PasswordField password = new PasswordField();
    password.setPromptText("Password");

    //Submit button
    Button submitBtn = new Button();
    submitBtn.setPrefSize(120, 40);
    submitBtn.textProperty().bind(readOnlySubmit);

    //HBox for employee id
    HBox empLayout = new HBox(5);
    empLayout.setPadding(new Insets(10, 20, 10, 20));
    empLayout.getChildren().addAll(empIdfield, employeeid);
    empLayout.setLayoutX(12);
    empLayout.setLayoutY(12);
    HBox.setHgrow(empIdfield, Priority.ALWAYS);
    HBox.setHgrow(employeeid, Priority.ALWAYS);
    empLayout.setAlignment(Pos.CENTER);

    //HBox for password field
    HBox passwordLayout = new HBox(20);
    passwordLayout.setPadding(new Insets(20, 20, 20, 20));
    passwordLayout.getChildren().addAll(passwordField, password);
    passwordLayout.setLayoutX(12);
    passwordLayout.setLayoutY(12);
    HBox.setHgrow(passwordField, Priority.ALWAYS);
    HBox.setHgrow(password, Priority.ALWAYS);
    passwordLayout.setAlignment(Pos.CENTER);

    //Layout for the form
    VBox formLayout = new VBox();

    //Adding form fields to the layout
    formLayout.getChildren().addAll(empLayout, passwordLayout, submitBtn);
    formLayout.setLayoutX(12);
    formLayout.setLayoutY(12);
    formLayout.setAlignment(Pos.CENTER);

    //login button event listener
    submitBtn.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {
            stage.setScene(scene2);
            c = JDBCDemo.connect();
        }
    });

    return formLayout;
}

请告诉我哪里弄错了。我是JAVAFX的新手