Javafx中“ScheduledService”的简单示例 [英] Simple example for 'ScheduledService' in Javafx

问题描述

我是一名学生，一个月以来学习JavaFX。
我正在开发一个应用程序，我希望服务在执行任务后重复启动。为此我已经知道' ScheduledService '被使用了。
所以任何人都可以通过简单的例子解释预定服务的使用，以及它与JavaFX中的服务的区别。谢谢;）

I am a student and learning JavaFX since a month. I am developing a application where I want a service to repeatedly start again after its execution of the task. For this I have come to know that 'ScheduledService' is used. So can anybody please explain the use of scheduledservice with simple example and also how it differs from the 'Service' in JavaFX. Thanks ;)

编辑：如何定义这个名为DataThread的ScheduledService应该每5秒重启一次？

EDIT : How can I define that this ScheduledService named DataThread should be restarted every 5 seconds ?

public class DataThread extends ScheduledService<Void>
{
    @Override
    public Task<Void> createTask() {
        return new Task<Void>() {
            @Override
            public Void call() throws Exception {
             for(i=0;i<10;i++)
             {
                 System.out.println(""+i);
             }
              return null;
            }
        };
    }
}  

推荐答案

考虑您对 服务有充分的了解 类。 ScheduledService 只是具有计划功能的服务。

Considering you have a sound knowledge of Service class. ScheduledService is just a Service with a Scheduling functionality.

来自文档

ScheduledService是一个服务，它会在成功执行后自动重启，在某些情况下即使发生故障也会重启

The ScheduledService is a Service which will automatically restart itself after a successful execution, and under some conditions will restart even in case of failure

所以我们可以这样说，

Service -> Execute One Task
ScheduledService -> Execute Same Task at regular intervals

计划服务的一个非常简单的例子是TimerService，它计算数字已调用服务任务的次数。它计划每1秒调用一次

A very simple example of Scheduled Service is the TimerService, which counts the number of times the Service Task has been called. It is scheduled to call it every 1 second

import java.util.concurrent.atomic.AtomicInteger;

import javafx.application.Application;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.concurrent.ScheduledService;
import javafx.concurrent.Task;
import javafx.concurrent.WorkerStateEvent;
import javafx.event.EventHandler;
import javafx.stage.Stage;
import javafx.util.Duration;

public class TimerServiceApp extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        TimerService service = new TimerService();
        AtomicInteger count = new AtomicInteger(0);
        service.setCount(count.get());
        service.setPeriod(Duration.seconds(1));
        service.setOnSucceeded(new EventHandler<WorkerStateEvent>() {

            @Override
            public void handle(WorkerStateEvent t) {
                System.out.println("Called : " + t.getSource().getValue()
                        + " time(s)");
                count.set((int) t.getSource().getValue());
            }
        });
        service.start();
    }

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

    private static class TimerService extends ScheduledService<Integer> {
        private IntegerProperty count = new SimpleIntegerProperty();

        public final void setCount(Integer value) {
            count.set(value);
        }

        public final Integer getCount() {
            return count.get();
        }

        public final IntegerProperty countProperty() {
            return count;
        }

        protected Task<Integer> createTask() {
            return new Task<Integer>() {
                protected Integer call() {
                    //Adds 1 to the count
                    count.set(getCount() + 1);
                    return getCount();
                }
            };
        }
    }
}

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