java jfreechart需要自定义Y轴，以便打印

Question

我已经生成了一个图形，它是完美的，除了Y轴是以秒为单位的，如图所示

我不想改变刻度单位或范围，我只想用HH:mm:ss共振峰打印出来

比如说

7500 seconds = 02:05:00

不确定在绘制图形时是否可以将7500秒的值修改为HH:mm:ss

我尝试了JFreeChart-SymbolAxis-NumberAxis，但找不到解决方法。有人能告诉我正确的API或类似的问题吗

Answer 1

没有代码很难提供帮助，但我怀疑您需要为XYPlot创建一个StandardXYItemRenderer，然后创建一个适合您需要的StandardXYTooltipGenerator。这是我的一张图表的复制粘贴，我必须在其中操作X轴的工具提示。也许这有助于：

 public JFreeChart createChart() {

    String title = "MyChart";

    IntervalXYDataset dataset1;
    dataset1 = createDataset();
    XYBarRenderer renderer1 = new XYBarRenderer(0.20000000000000001D);
    renderer1.setBaseToolTipGenerator(new StandardXYToolTipGenerator("{0}: ({1}, {2})", new SimpleDateFormat("EE, d-MMM-yyyy"), new DecimalFormat("0.00")));
    renderer1.setSeriesPaint(0, Color.BLUE);
    renderer1.setDefaultShadowsVisible(false);
    DateAxis domainAxis = new DateAxis("Datum");
    domainAxis.setTickMarkPosition(DateTickMarkPosition.MIDDLE);
    NumberAxis valueAxis = new NumberAxis("Anzahl");
    XYPlot plot = new XYPlot(dataset1, domainAxis, valueAxis, renderer1);
    XYDataset dataset2 = createBettenDataset();
    StandardXYItemRenderer renderer2 = new StandardXYItemRenderer();
    renderer2.setBaseToolTipGenerator(new StandardXYToolTipGenerator("{0}: ({1}, {2})", new SimpleDateFormat("EE, d-MMM-yyyy"), new DecimalFormat("0.00")));
    renderer2.setSeriesPaint(0, Color.CYAN);
    renderer2.setSeriesStroke(0, new BasicStroke(2));
    plot.setDataset(1, dataset2);
    plot.setRenderer(1, renderer2);
    XYDataset dataset3 = createMaxBelegungDataset();
    StandardXYItemRenderer renderer3 = new StandardXYItemRenderer();
    renderer3.setBaseToolTipGenerator(new StandardXYToolTipGenerator("{0}: ({1}, {2})", new SimpleDateFormat("EE, d-MMM-yyyy"), new DecimalFormat("0.00")));
    renderer3.setSeriesPaint(0, Color.RED);
    renderer3.setSeriesStroke(0, new BasicStroke(4));
    plot.setDataset(2, dataset3);
    plot.setRenderer(2, renderer3);

    plot.setDatasetRenderingOrder(DatasetRenderingOrder.FORWARD);

    JFreeChart chart = new JFreeChart(title, JFreeChart.DEFAULT_TITLE_FONT, plot, true);

    return chart;

}

Answer 2

您可以使用NumberAxis类中的setNumberFormatOverride（）方法来提供自定义格式化程序。唯一的问题是您需要一个NumberFormat子类，它可以将表示秒的数字转换为HH:MM:SS格式。我不知道是否有一个现有的，但它并不难写自己的。这是我的第一次尝试，它似乎有效，但需要一些测试（我可能会在下一个JFreeChart版本中包括这一点）：

package org.jfree.chart.util;

import java.text.DecimalFormat;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;

/**
 * A custom number formatter that formats numbers (in seconds) as HH:MM:SS.
 *
 * @since 1.0.17
 */
public class HMSNumberFormat extends NumberFormat {

    private NumberFormat hourFormatter = new DecimalFormat("00");
    private NumberFormat minuteFormatter = new DecimalFormat("00");
    private NumberFormat secondFormatter = new DecimalFormat("00");

    /**
     * Creates a new instance.
     */
    public HMSNumberFormat() {

    }

    /**
     * Formats the specified number as a string of the form HH:MM:SS.  The 
     * decimal fraction is ignored.
     *
     * @param number  the number to format.
     * @param toAppendTo  the buffer to append to (ignored here).
     * @param pos  the field position (ignored here).
     *
     * @return The string buffer.
     */
    @Override
    public StringBuffer format(double number, StringBuffer toAppendTo,
            FieldPosition pos) {
        return format((long) number, toAppendTo, pos);
    }

    /**
     * Formats the specified number as a string of the form HH:MM:SS.
     *
     * @param number  the number to format.
     * @param toAppendTo  the buffer to append to (ignored here).
     * @param pos  the field position (ignored here).
     *
     * @return The string buffer.
     */
    @Override
    public StringBuffer format(long number, StringBuffer toAppendTo,
            FieldPosition pos) {
        StringBuffer sb = new StringBuffer();
        long hours = number / 3600;
        sb.append(this.hourFormatter.format(hours)).append(":");
        long remaining = number - (hours * 3600);
        long minutes = remaining / 60;
        sb.append(this.minuteFormatter.format(minutes)).append(":");
        long seconds = remaining - (minutes * 60);
        sb.append(this.secondFormatter.format(seconds));
        return sb;
    }

    /**
     * Parsing is not implemented, so this method always returns
     * <code>null</code>.
     *
     * @param source  ignored.
     * @param parsePosition  ignored.
     *
     * @return Always <code>null</code>.
     */
    @Override
    public Number parse (String source, ParsePosition parsePosition) {
        return null; // don't bother with parsing
    }

}