JavaFX - 控制和并发

Question

我有一个示例 Hello World JavaFx。我正在使用 Eclipse 和 eFxclipse 插件。我的Eclipse是kepler，它是Eclipse 4.3.2版本，Java服务是Jdk1.7-045。

我尝试添加的并发代码非常少，我只想更新示例中的按钮文本。此后端任务能否与前端 UI 控件(例如按钮、场景)交互？如果没有，我如何定制后端任务，然后与 UI 控件交互？

提前致谢

package com.juhani.fx.exer;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import javafx.application.Application;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;


public class HelloWorld extends Application{

    private static final short COREPOOLSIZE=2;
    private static final short MAXIMUMPOOLSIZE=2; 
    private static final int WORKQUEUECAPACITY=100;
    private static Logger log = LogManager.getLogger(
            HelloWorld.class.getName());

    private ExecutorService executors = new             ThreadPoolExecutor(COREPOOLSIZE,MAXIMUMPOOLSIZE,20,TimeUnit.MINUTES,new ArrayBlockingQueue<Runnable>(WORKQUEUECAPACITY));



    public static void main(String[] args) {
       LogMessage logMessage = new LogMessage("BEGIN",1.0,1,"HELLOWORLD");
       log.trace(logMessage.toString());
       launch(args);        

   }

   @Override
   public void start(final Stage primaryStage) throws InterruptedException {
      primaryStage.setTitle("Hello World!");
      final Button btn = new Button();
      btn.setText("Say 'Hello World'");
      btn.setOnAction(new EventHandler<ActionEvent>() {
          @Override
          public void handle(ActionEvent event) {
            System.out.println("Hello World!");
         }
       });

      final StackPane root = new StackPane();
      root.getChildren().add(btn);
      final Scene scene= new Scene(root,300,250);
      primaryStage.setScene(scene);
      primaryStage.show();

      Task<Boolean> task = new Task<Boolean>() {
         @Override 
         public Boolean call() {    
            for(int i=0;i<20;i++){
               btn.setText("First row\nSecond row "+i);
               primaryStage.show();
               try {
                  Thread.sleep(1000);
               } catch (InterruptedException e) {
                  log.error(new LogMessage("entering interruption",1.0,2,"exception").toString());                       
               }
            }
            return new Boolean(true);               
          }        
       };           
       executors.submit(task);      
    }   
}

Answer 1

这个答案专门讲了Platform.runLater的使用。如果您使用的是 Task，则最好使用它提供的方法更新 UI，如 kleopatra's answer .

<小时/>

要更新 UI，您必须位于 Javafx 线程上。

一旦您进入任何其他线程，请使用 Platform.runLater()将这些数据更新回 Javafx UI。下面可以找到一个工作示例

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;


public class HelloWorld extends Application {

    private static final short COREPOOLSIZE = 2;
    private static final short MAXIMUMPOOLSIZE = 2; 
    private static final int WORKQUEUECAPACITY = 100;

    private ExecutorService executors = new 
       ThreadPoolExecutor(COREPOOLSIZE, MAXIMUMPOOLSIZE, 20, TimeUnit.MINUTES,
                          new ArrayBlockingQueue<Runnable>(WORKQUEUECAPACITY));

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

    @Override
    public void start(final Stage primaryStage) throws InterruptedException {
        primaryStage.setTitle("Hello World!");
        final Button btn = new Button();
        btn.setText("Say 'Hello World'");
        btn.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                System.out.println("Hello World!");
            }
        });

        final StackPane root = new StackPane();
        root.getChildren().add(btn);
        final Scene scene = new Scene(root, 300, 250);
        primaryStage.setScene(scene);
        primaryStage.show();

        Task<Boolean> task = new Task<Boolean>() {
            @Override 
            public Boolean call() {    
                final AtomicInteger i = new AtomicInteger(0);
                for( ; i.get() < 20; i.incrementAndGet()) {
                    Platform.runLater(new Runnable() {
                        @Override
                        public void run() {
                            btn.setText("First row\nSecond row " + i);                      
                        }
                    });

                try {
                  Thread.sleep(1000);
                }
                catch (InterruptedException e) {}
            }
            return Boolean.valueOf(true);               
          }        
       };           
       executors.submit(task);      
    }   
}

有关更多信息，您可以访问提供的链接 here