Question

它宁愿是一个非常简单的概念，但因为我对JavaFX中的并发性完全不熟悉。我一直在努力理解这个概念。

在构建一个非常简单的JavaFX应用程序时，我想在后台执行一些冗长的任务，并保证UI不会冻结。

在下面的示例中，我尝试创建一个简单的后台任务服务，然后使用ControlsFX Dialog在主UI窗口上显示进度条。

但是，我想知道如何为此服务提供一些输入参数并从中获取布尔输出。这在C＃BackgroundWorker中非常简单，但在JavaFX中仍然无法弄清楚。任何提示都会有很大的帮助。

试过这个简单的例子

    public void runTask(Stage stage) throws URISyntaxException, IOException {

    Service<Void> service = new Service<Void>() {

        @Override
        protected Task<Void> createTask() {
            return new Task<Void>() {
                @Override
                protected Void call() throws InterruptedException, URISyntaxException, IOException {
                    // some time consuming task here
                    // use the input arguments and perform some action on it
                    // then set the process result to a Boolean and return after the task is completed
                    // also keep hold back any other process to from executing on UI 
                    return null;
                }
            };
        }

    };

    Dialogs.create()
            .owner(stage)
            .title("Performing Task!")
            .masthead("Please wait...")
            .showWorkerProgress(service);

    service.setOnSucceeded(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            System.out.println("done:" + event.getSource().getValue());
        }
    });

    service.setOnFailed(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            throw new UnsupportedOperationException("Failed."); //To change body of generated methods, choose Tools | Templates.
        }
    });

    service.setOnCancelled(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            throw new CancellationException("Cancelled."); //To change body of generated methods, choose Tools | Templates.
        }
    });

    service.start();

}

Answer 1

对于输入参数，只需为方法定义一些参数即可。（您需要它们在Java 7中为final。）

要返回Boolean，只需定义Service和Task的类型Boolean：

public void runTask(Stage stage, final int input /* can be any type */) throws URISyntaxException, IOException {

    Service<Boolean> service = new Service<Boolean>() {

        @Override
        protected Task<Boolean> createTask() {
            return new Task<Boolean>() {
                @Override
                protected Boolean call() throws InterruptedException, URISyntaxException, IOException {
                    // some time consuming task here
                    // use the input arguments and perform some action on it
                    // then set the process result to a Boolean and return after the task is completed
                    // also keep hold back any other process to from executing on UI 

                    Boolean returnValue = ... ;
                    return returnValue;
                }
            };
        }

    };

    Dialogs.create()
            .owner(stage)
            .title("Performing Task!")
            .masthead("Please wait...")
            .showWorkerProgress(service);

    service.setOnSucceeded(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            System.out.println("done:" + event.getSource().getValue());
        }
    });

    service.setOnFailed(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            throw new UnsupportedOperationException("Failed."); //To change body of generated methods, choose Tools | Templates.
        }
    });

    service.setOnCancelled(new EventHandler<WorkerStateEvent>() {

        @Override
        public void handle(WorkerStateEvent event) {
            throw new CancellationException("Cancelled."); //To change body of generated methods, choose Tools | Templates.
        }
    });

    service.start();

}

JavaFX中具有输入和输出参数的并发后台任务或服务

1 个答案: