JavaFX 中具有输入和输出参数的并发后台任务或服务

Question

它宁愿是一个非常简单的概念，但因为我对 JavaFX 中的并发完全陌生。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防止 UI 冻结。

在下面的示例中，我试图创建一个简单的后台任务服务，然后使用 ControlsFX 对话框在主界面上显示进度条 UI window。

但是，我想知道如何为该服务提供一些输入参数并从中获取布尔值输出。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。（您需要 final in Java 7。）

到return一个Boolean，只需定义你的Service和Task的类型为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

Concurrent background Task or Service with input and output arguments in JavaFX

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service

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task