javaFX：如何定期从数据库加载信息并将其显示在标签上？

Question

我想定期执行一个方法，这个方法从数据库中获取信息并将其显示到标签中，我尝试了以下代码：

 Timer timer = new Timer();
            timer.scheduleAtFixedRate(new TimerTask() {
             @Override
             public void run() {
                 //update information
                 miseAjour();
             }
            }, 0, 2000);

当我运行主程序时，后台服务运行也正常但是当数据库上的信息发生变化时我得到这个异常：

Exception in thread "Timer-0" java.lang.IllegalStateException: Not on FX application thread; currentThread = Timer-0

这是方法 miseAjour 的代码：

public void miseAjour(){
    try {

        dbConnection db = new dbConnection();
        Connection connect = db.connectiondb();
        connect.setAutoCommit(false);
        Statement stmt= connect.createStatement();
        ResultSet rs = stmt.executeQuery("SELECT count(*) as nbrAderent  FROM  gss_aderent ");  
        int nbrAderent = rs.getInt("nbrAderent"); 
        rs.close();
        stmt.close();
        connect.commit();
        connect.close();
        main_nbrAdrTot.setText(nbrAderent + "");
    } catch (SQLException ex) {
        Logger.getLogger(SimpleController.class.getName()).log(Level.SEVERE, null, ex);
    }
   }

Answer 1

你可以为此使用 Timer，但我建议使用 API 提供的 JavaFX，称为 ScheduledService。

ScheduledService 是针对 execute the same Task at regular intervals 的，因为它在内部创建了一个 Task，所以有 API 可以帮助您将值绑定到 UI 控件。

ScheduledService<Object> service = new ScheduledService<Object>() {
     protected Task<Object> createTask() {
         return new Task<Object>() {
             protected Object call() {
                 // Call the method and update the message
                 updateMessage(miseAjour());
                 return object; // Useful in case you want to return data, else null
             }
         };
     }
 };
 service.setPeriod(Duration.seconds(10)); //Runs every 10 seconds

 //bind the service message properties to your Label
 label.textProperty().bind(service.messageProperty()); // or use your label -> main_nbrAdrTot

在 dbcall 方法中 miseAjour，return 您已获取的值，并且您希望使用 :

更新标签

public String miseAjour(){
    String nbrAderent = null;
    try {
        dbConnection db = new dbConnection();
        Connection connect = db.connectiondb();
        connect.setAutoCommit(false);
        Statement stmt= connect.createStatement();
        ResultSet rs = stmt.executeQuery("SELECT count(*) as nbrAderent  FROM  gss_aderent ");  
        nbrAderent = String.valueOf(rs.getInt("nbrAderent")); 
        connect.commit();
    } catch (SQLException ex) {
        Logger.getLogger(SimpleController.class.getName()).log(Level.SEVERE, null, ex);
    }
    finally {
        rs.close();
        stmt.close();
        connect.close();
    }
    return nbrAderent;
}

Answer 2

最后我解决了问题，这是代码：

public class TimerServiceApp {
    public void start() throws Exception {
        TimerService service = new TimerService();
        service.setPeriod(Duration.seconds(10));
        service.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent t) {
                main_nbrAdrTot.setText(t.getSource().getMessage());
            }
        });
        service.start();
    }



    private class TimerService extends ScheduledService<Integer> {
        private final StringProperty  nbrTotAderent = new SimpleStringProperty();


         public final void  setTotalAderentNumber(String value ) {
             nbrTotAderent.set(value);
         }


        public String getTotalAderentNumber() throws SQLException  {
        String nbrAderent = null;
        ResultSet rs=null;
        Statement stmt=null;
        Connection connect=null;

        try {
        dbConnection db = new dbConnection();
        connect = db.connectiondb();
        connect.setAutoCommit(false);
        stmt= connect.createStatement();
        rs = stmt.executeQuery("SELECT count(*) as nbrAderent  FROM  gss_aderent ");  
        nbrAderent = String.valueOf(rs.getInt("nbrAderent")); 
        connect.commit();
        } catch (SQLException ex) {
        Logger.getLogger(SimpleController.class.getName()).log(Level.SEVERE, null, ex);
        }
        finally {
        rs.close();
        stmt.close();
        connect.close();
        }
        System.out.println(" Total aderent number updated to :" + nbrAderent + " Aderents ");
        return nbrAderent;
        }

        protected Task<Integer> createTask() {
            return new Task<Integer>() {
                protected Integer call() throws SQLException {

                    nbrTotAderent.setValue(getTotalAderentNumber());
                    updateMessage(getTotalAderentNumber());
                    return  Integer.parseInt(getTotalAderentNumber());
                }
            };
        }
    }
} `

我通过以下方式调用此服务：

 TimerServiceApp s = new TimerServiceApp();
        s.start();

我不知道该解决方案是否经过优化但它有效 :) 谢谢@ItachiUchiha 我从您在以下

中的回答中获取了解决方案

javaFX：如何定期从数据库加载信息并将其显示在标签上？

javaFX : How to periodically load information from db and show it on a Label?

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