JavaFX - 从 gui 接收事件后返回主线程

Question

我正在编写 JavaFX 应用程序并意识到 FX 线程上发生了太多事情。根本原因之一是 gui 事件，如按钮单击，在 FX 线程上产生后端操作。实际上，在收到事件后，我们就在 FX 线程上，所以任何进一步的调用都在它上面。有什么方法可以简单地返回到 MAIN 应用程序线程，然后在需要时返回 Platform.runLater，或者我必须使用例如 RX 或某些执行程序服务来处理它？<​​/p>

谢谢

Answer 1

退出事件循环的方式非常简单——就是 Java。使用您通常会使用的任何东西——执行程序、队列等。

例如，要“在后台”完成一些事情然后更新 GUI，您可以做类似的事情

final Executor backgroundWorker = Executors.newSingleThreadExecutor();
...
backgroundWorker.execute(()-> // from the EventLoop into the Worker
{
    val result = doThatLongRunningTask();
    Platform.runLater(() -> // back from the Worker to the Event Loop
    {
        updateUiWithResultOfLongRunningTask(result);
    }
});

我通常希望将 main 线程提供给事件循环，并使用自定义执行程序进行后台工作(因为后台工作是特定于应用程序的，所以可能需要更多线程，等等。 ).

---

如果出于任何异国情调的原因(我真的想不出)你想要相反的方式:

因此，要将主线程用作执行器，我们只需要:

public final class MyApp extends Application {
    private static final Logger LOG = LoggerFactory.getLogger(MyApp.class);
    private static final Runnable POISON_PILL = () -> {}; 
    private final BlockingQueue<Runnable> tasks = new LinkedBlockingQueue<>();
    private final Executor backgroundWorker = this::execute;
    private final Future<Void> shutdownFuture = new CompletableFuture<>();
    private final Executor eventLoop = Executors.newSingleThreadExecutor();

    /** Get background worker */
    public Executor getBackgroundWorker() {
        return backgroundWorker;
    } 

    /** Request backgroun worker shutdown */
    public Future shutdownBackgroundWorker() {
        execute(POISON_PILL);
        return shutdownFuture;
    }

    private void execute(Runnable task) {
        tasks.put(task);
    }

    private void runWorkerLoop() throws Throwable {
        Runnable task;
        while ((task = tasks.take()) != POISON_PILL) {
            task.run();
        }
        shutdownFuture.complete(null);
    }

    public static void main (String... args) throws Throwable {
        final MyApp myApp = new MyApp(args);        

        LOG.info("starting JavaFX (background) ...");
        eventLoop.execute(myApp::launch);

        LOG.info("scheduling a ping task into the background worker...");
        myApp.runLater(() -> {
            LOG.info("#1 we begin in the event loop");
            myApp.getBackgroundWorker().execute(() -> {
                LOG.info("#2 then jump over to the background worker");
                myApp.runLater(() -> {
                    LOG.info("#3 and then back to the event loop");
                });
            });
        });

        LOG.info("running the backgound worker (in the foreground)...");
        myApp.runWorkerLoop();
    }
}