java - 在启动时启动方法

Question

我有一个名为databaseConnection的类，我想在应用程序启动时启动/执行它，似乎我应该从start方法(我称之为MainApp)调用它，但我似乎找不到正确的方法这样做，因此我的问题

我觉得很简单，但我真的搞不懂

数据库连接:

package albertheijnhandterminal;

import java.net.URL;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.util.ResourceBundle;

/**
 *
 * @author Stanly
 */
public class databaseConnection {

    private static String dbURL = "jdbc:derby://localhost:1527/AlbertHeijnHandterminal;create=true;user=StanlySuijk;password=hoi55455";
    private static Connection connection = null;
    private static Statement statement = null;

    public static void main(String[] args) {

        createConnection();
        //insertUsers("");
        //selectUsers();
        //shutdown();

    }

    private static void createConnection() {
        try {
            Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
            //Get a connection
            connection = DriverManager.getConnection(dbURL);

        } catch (Exception exception) {

        }

    }

}

主应用程序:

package albertheijnhandterminal;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import static javax.management.remote.JMXConnectorFactory.connect;

/*
 1
 9 @author Stanly
 9 
 9
 */
public class MainApp extends Application {


    public static FrameController theFrameController = null;

    static StackPane displayPane;

    public static Connection connection = null;
    public static Statement statement = null;
    public static PreparedStatement preparedStatement = null;
    public static ResultSet resultSet = null;

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

        Parent root = FXMLLoader.load(getClass().getResource("Frame.fxml"));

        Scene scene = new Scene(root);

        stage.setTitle("Albert Heijn Handterminal");
        stage.setScene(scene);
        stage.show();

    }

    public static void main(String[] args) {
        launch(args);
    }

}

我只编程了大约 6 个月，所以如果您看到我的代码有一些改进，我们将不胜感激。

Answer 1

如果您的应用程序是 MainApp 类，那么该类应该具有 main 方法。那么你应该执行以下操作。

public static void main(String[] args) {
   databaseConnection db = new databaseConnection ();
   db.createConnection();
   launch(args);
}

或者调用另一个类的main方法。

如果不需要参数

public static void main(String[] args) {
    databaseConnection.main(null);
    launch(args);
}

如果需要参数

 public static void main(String[] args) {
    databaseConnection.main(args);
    launch(args);
 }

更新:

正如 James_D 在评论中指出的:

Under some circumstances you might want the application to be launched using a "pure JavaFX launch", which would bypass the main() method entirely

在这种情况下，最好移动这个

databaseConnection db = new databaseConnection ();
db.createConnection();

到 start() 方法。

public void start(Stage stage) throws Exception {

    databaseConnection db = new databaseConnection ();
    db.createConnection();

    Parent root = FXMLLoader.load(getClass().getResource("Frame.fxml"));

    Scene scene = new Scene(root);

    stage.setTitle("Albert Heijn Handterminal");
    stage.setScene(scene);
    stage.show();

}