Question

如何使用java中的jFree图表创建动态折线图，该图表显示2小时前的数据，并且还提供一个空白区域，数据显示从当前时间开始2小时。例如假设当前时间是下午4点，所以图表显示数据从下午2点到下午6点。下午2点到下午4点，图表显示一条线，下午4点到下午6点提供一个空白区域，这是图形移动时填充的时间，这意味着该图形的尾部从中间开始向右移动。类似于股市图表。

Answer 1

是的，你可以做到。几天前我遇到了类似的问题。

DynamicLineAndTimeSeriesChart.java

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Timer;
import javax.swing.JPanel;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.time.Millisecond;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

/**
 * An example to show how we can create a dynamic chart.
*/
public class DynamicLineAndTimeSeriesChart extends ApplicationFrame implements ActionListener {

    /** The time series data. */
    private TimeSeries series;

    /** The most recent value added. */
    private double lastValue = 100.0;

    /** Timer to refresh graph after every 1/4th of a second */
    private Timer timer = new Timer(250, this);

    /**
     * Constructs a new dynamic chart application.
     *
     * @param title  the frame title.
     */
    public DynamicLineAndTimeSeriesChart(final String title) {

        super(title);
        this.series = new TimeSeries("Random Data", Millisecond.class);

        final TimeSeriesCollection dataset = new TimeSeriesCollection(this.series);
        final JFreeChart chart = createChart(dataset);

        timer.setInitialDelay(1000);

        //Sets background color of chart
        chart.setBackgroundPaint(Color.LIGHT_GRAY);

        //Created JPanel to show graph on screen
        final JPanel content = new JPanel(new BorderLayout());

        //Created Chartpanel for chart area
        final ChartPanel chartPanel = new ChartPanel(chart);

        //Added chartpanel to main panel
        content.add(chartPanel);

        //Sets the size of whole window (JPanel)
        chartPanel.setPreferredSize(new java.awt.Dimension(800, 500));

        //Puts the whole content on a Frame
        setContentPane(content);

        timer.start();

    }

    /**
     * Creates a sample chart.
     *
     * @param dataset  the dataset.
     *
     * @return A sample chart.
     */
    private JFreeChart createChart(final XYDataset dataset) {
        final JFreeChart result = ChartFactory.createTimeSeriesChart(
            "Dynamic Line And TimeSeries Chart",
            "Time",
            "Value",
            dataset,
            true,
            true,
            false
        );

        final XYPlot plot = result.getXYPlot();

        plot.setBackgroundPaint(new Color(0xffffe0));
        plot.setDomainGridlinesVisible(true);
        plot.setDomainGridlinePaint(Color.lightGray);
        plot.setRangeGridlinesVisible(true);
        plot.setRangeGridlinePaint(Color.lightGray);

        ValueAxis xaxis = plot.getDomainAxis();
        xaxis.setAutoRange(true);

        //Domain axis would show data of 60 seconds for a time
        xaxis.setFixedAutoRange(60000.0);  // 60 seconds
        xaxis.setVerticalTickLabels(true);

        ValueAxis yaxis = plot.getRangeAxis();
        yaxis.setRange(0.0, 300.0);

        return result;
    }
    /**
     * Generates an random entry for a particular call made by time for every 1/4th of a second.
     *
     * @param e  the action event.
     */
    public void actionPerformed(final ActionEvent e) {

        final double factor = 0.9 + 0.2*Math.random();
        this.lastValue = this.lastValue * factor;

        final Millisecond now = new Millisecond();
        this.series.add(new Millisecond(), this.lastValue);

        System.out.println("Current Time in Milliseconds = " + now.toString()+", Current Value : "+this.lastValue);
    }

    /**
     * Starting point for the dynamic graph application.
     *
     * @param args  ignored.
     */
    public static void main(final String[] args) {

        final DynamicLineAndTimeSeriesChart demo = new DynamicLineAndTimeSeriesChart("Dynamic Line And TimeSeries Chart");
        demo.pack();
        RefineryUtilities.centerFrameOnScreen(demo);
        demo.setVisible(true);

    }

}

请查看此处：

http://blog.odoobiz.com/2012/07/how-to-draw-dynamic-line-or-timeseries.html

在java中使用jfree图表制作动态折线图

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