Question

我有这个用于更新图表的JavaFX任务：

public class LiveRAMPerformance
{

    private static final int MAX_DATA_POINTS = 50;

    private Series series;
    private int xSeriesData = 0;
    private ConcurrentLinkedQueue<Number> dataQ = new ConcurrentLinkedQueue<Number>();
    private ExecutorService executor;
    private AddToQueue addToQueue;
    //private Timeline timeline2;
    private NumberAxis xAxis;

        public AreaChart<Number, Number> init()
    {
        xAxis = new NumberAxis(0, MAX_DATA_POINTS, MAX_DATA_POINTS / 10);
        xAxis.setForceZeroInRange(false);
        xAxis.setAutoRanging(false);

        xAxis.setTickLabelsVisible(false);
        xAxis.setTickMarkVisible(false);
        xAxis.setMinorTickVisible(false);

        NumberAxis yAxis = new NumberAxis();
        yAxis.setAutoRanging(true);

        //-- Chart
        final AreaChart<Number, Number> sc = new AreaChart<Number, Number>(xAxis, yAxis)
        {
            // Override to remove symbols on each data point
            @Override
            protected void dataItemAdded(Series<Number, Number> series, int itemIndex, Data<Number, Number> item)
            {
            }
        };
        sc.setAnimated(false);
        sc.setId("liveAreaChart");
        sc.setTitle("Animated Area Chart");

        //-- Chart Series
        series = new AreaChart.Series<Number, Number>();
        series.setName("Area Chart Series");
        sc.getData().add(series);

        // look up first series fill
        Node node = sc.lookup(".default-color0.chart-series-area-fill");
        // set the first series fill to translucent pale green
        node.setStyle("-fx-fill: linear-gradient(#f2f2f2, #d4d4d4);"
            + "  -fx-background-insets: 0 0 -1 0, 0, 1, 2;"
            + "  -fx-background-radius: 3px, 3px, 2px, 1px;");

        Node nodew = sc.lookup(".chart-series-area-line");
        // set the first series fill to translucent pale green
        nodew.setStyle("-fx-stroke: #989898; -fx-stroke-width: 1px; ");

        executor = Executors.newCachedThreadPool(new ThreadFactory()
        {
            @Override
            public Thread newThread(Runnable r)
            {
                Thread thread = new Thread(r);
                thread.setDaemon(true);
                return thread;
            }
        });
        addToQueue = new AddToQueue();
        executor.execute(addToQueue);
        //-- Prepare Timeline
        prepareTimeline();

        return sc;
    }

    private class AddToQueue implements Runnable
    {
        @Override
        public void run()
        {
            try
            {
                // add a item of random data to queue
                dataQ.add(Math.random());
                Thread.sleep(1150);
                executor.execute(this);
            }
            catch (InterruptedException ex)
            {
                //Logger.getLogger(MainApp.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    //-- Timeline gets called in the JavaFX Main thread
    private void prepareTimeline()
    {
        // Every frame to take any data from queue and add to chart
        new AnimationTimer()
        {
            @Override
            public void handle(long now)
            {
                addDataToSeries();
            }
        }.start();
    }

    private void addDataToSeries()
    {
        for (int i = 0; i < 20; i++)
        { //-- add 20 numbers to the plot+
            if (dataQ.isEmpty())
                break;
            series.getData().add(new AreaChart.Data(xSeriesData++, dataQ.remove()));
        }
        // remove points to keep us at no more than MAX_DATA_POINTS
        if (series.getData().size() > MAX_DATA_POINTS)
        {
            series.getData().remove(0, series.getData().size() - MAX_DATA_POINTS);
        }
        // update
        xAxis.setLowerBound(xSeriesData - MAX_DATA_POINTS);
        xAxis.setUpperBound(xSeriesData - 1);
    }
}

当我最小化图表或切换面板时，任务i仍在运行并消耗CPU资源。如何让Task只有在用户可见的情况下才能运行？当我不可见时，我想释放资源。

修改

这可能是解决方案：

sc.visibleProperty().addListener(new ChangeListener<Boolean>()
        {
            @Override
            public void changed(final ObservableValue<? extends Boolean> observableValue, final Boolean aBoolean, final Boolean aBoolean2)
            {
                System.out.println("####");
                //To change body of implemented methods use File | Settings | File Templates.
            }
        });

Answer 1

如果数据随时可用（即检索或计算不需要很长时间），那么您根本不需要所有的线程机制。只需使用Timeline和KeyFrame EventHandler即可更新图表。然后，当图表从显示中移除时，您可以在pause()上调用Timeline，并在显示图表时调用play()。

Timeline timeline = new Timeline(new KeyFrame(Duration.millis(1150), 
    event -> {
        series.getData().add(new AreaChart.Data(xSeriesData++, Math.random()));
        if (series.getData().size() > MAX_DATA_POINTS) {
            series.getData().remove(0);
        }
    }));
timeline.setCycleCount(Animation.INDEFINITE);
timeline.play();

现在您可以摆脱Runnable，AnimationTimer，ConcurrentLinkedQueue和ExecutorService。

因此，举例来说，如果您的图表位于名为Tab的{{1}}中，而chartTab名为TabPane，则可以

tabPane

停止任务，如果它不可见

1 个答案: