Question

我最近发现JFreeChart用于生成简单的饼图。基本上我想显示带有标签值（以百分比表示）的馅饼，但它只显示没有值的标签名称。

这是我的代码：

package testPie;

// Import the Swing classes
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// Import the JFreeChart classes
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.data.*;
import org.jfree.data.general.*;

public class First extends JPanel
{
  // Holds the data
  private DefaultPieDataset dataset = new DefaultPieDataset();

  // Create a set of charts
  private JFreeChart chart1;
  private JFreeChart chart2;
  private JFreeChart chart3;
  private JFreeChart chart4;

  // Create a set of panels that can show charts
  private ChartPanel panel1;
  private ChartPanel panel2;
  private ChartPanel panel3;
  private ChartPanel panel4;

  public First()
  {
    // Initialize the dataset
    dataset.setValue( "California", new Double(10.0));
    dataset.setValue( "Arizona", new Double(8.0));
    dataset.setValue( "New Mexico", new Double(8.0));
    dataset.setValue( "Texas", new Double(40.0));
    dataset.setValue( "Louisiana", new Double(8.0) );
    dataset.setValue( "Mississippi", new Double(4.0));
    dataset.setValue( "Alabama", new Double(2.0));
    dataset.setValue( "Florida", new Double(20.0));

    // Create the charts
    chart1 = ChartFactory.createPieChart(
      "Driving Time Spent Per State (Flat Pie Chart)", // The chart title
      dataset,         // The dataset for the chart
      true,          // Is a legend required?
      true,          // Use tooltips
      false          // Configure chart to generate URLs?
    );
    chart2 = ChartFactory.createPieChart(
      "Driving Time Spent Per State (Exploded Pie Chart)", // The chart title
      dataset,         // The dataset for the chart
      true,          // Is a legend required?
      true,          // Use tooltips
      false          // Configure chart to generate URLs?
    );
    PiePlot plot = ( PiePlot )chart2.getPlot();
    plot.setExplodePercent( 3, 0.25 );

    chart3 = ChartFactory.createPieChart3D(
      "Driving Time Spent Per State (3D Pie Chart)", // The chart title
      dataset,         // The dataset for the chart
      true,          // Is a legend required?
      true,          // Use tooltips
      false          // Configure chart to generate URLs?
    );
    chart4 = ChartFactory.createPieChart3D(
      "Driving Time Spent Per State (3D with Transparency)", // The chart title
      dataset,         // The dataset for the chart
      true,          // Is a legend required?
      true,          // Use tooltips
      false          // Configure chart to generate URLs?
    );
    PiePlot3D plot4 = ( PiePlot3D )chart4.getPlot();
    plot4.setForegroundAlpha( 0.6f );

    // Create this panel
    this.setLayout( new GridLayout( 2, 2 ) );
    this.panel1 = new ChartPanel( chart1 );
    this.panel2 = new ChartPanel( chart2 );
    this.panel3 = new ChartPanel( chart3 );
    this.panel4 = new ChartPanel( chart4 );
    this.add( panel1 );
    this.add( panel2 );
    this.add( panel3 );
    this.add( panel4 );
  }

  public static void main( String[] args )
  {
    JFrame frame = new JFrame( "My Trip Driving From CA to FL..." );
    First chart = new First();
    frame.getContentPane().add( chart, BorderLayout.CENTER );
    frame.setSize( 640, 480 );
    frame.setVisible( true );
    frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
  }
}

我只是关注this tutorial，但我无法显示每个标签的值。

Answer 1

简单方法是使用旧版jfreechart，例如1.0.1。使用这个版本我得到了这个结果：

result with version 1.0.1

另一方面，使用最新版本的jfreechart（例如1.0.19）正在更改PieSectionLabelGenerator。默认值仅包含数据集的key 。

为此，您需要为标准标签生成器创建自定义标签格式，如下所示：

PieSectionLabelGenerator labelGenerator = new StandardPieSectionLabelGenerator("{0} = {1}");

更改所有图表的标签生成器，如下所示：

plot.setLabelGenerator(labelGenerator);

有了这个，我得到了这个结果：

result with version 1.0.19

如果您需要%，请使用标签格式{0} = {2}代替{0} = {1}，并显示California = 10%。

这是完整的例子：

public class First extends JPanel {

    private static final long serialVersionUID = 4400735172378226919L;

    public First() {
        final DefaultPieDataset dataset = new DefaultPieDataset();

        dataset.setValue("California", new Double(10.0));
        dataset.setValue("Arizona", new Double(8.0));
        dataset.setValue("New Mexico", new Double(8.0));
        dataset.setValue("Texas", new Double(40.0));
        dataset.setValue("Louisiana", new Double(8.0));
        dataset.setValue("Mississippi", new Double(4.0));
        dataset.setValue("Alabama", new Double(2.0));
        dataset.setValue("Florida", new Double(20.0));

        // Create the custom label generator
        final PieSectionLabelGenerator labelGenerator = new StandardPieSectionLabelGenerator("{0} = {1}");

        // Create the charts
        final JFreeChart chart1 = ChartFactory.createPieChart("Driving Time Spent Per State (Flat Pie Chart)", dataset, true, true, false);
        final PiePlot plot1 = (PiePlot) chart1.getPlot();
        plot1.setLabelGenerator(labelGenerator);

        final JFreeChart chart2 = ChartFactory.createPieChart("Driving Time Spent Per State (Exploded Pie Chart)", dataset, true, true, false);
        final PiePlot plot2 = (PiePlot) chart2.getPlot();
        plot2.setExplodePercent("3", 0.25);
        plot2.setLabelGenerator(labelGenerator);

        final JFreeChart chart3 = ChartFactory.createPieChart3D("Driving Time Spent Per State (3D Pie Chart)", dataset, true, true, false);
        final PiePlot3D plot3 = (PiePlot3D) chart3.getPlot();
        plot3.setLabelGenerator(labelGenerator);

        final JFreeChart chart4 = ChartFactory.createPieChart3D("Driving Time Spent Per State (3D with Transparency)", dataset, true, true, false);
        final PiePlot3D plot4 = (PiePlot3D) chart4.getPlot();
        plot4.setForegroundAlpha(0.6f);
        plot4.setLabelGenerator(labelGenerator);

        // Create this panel
        this.setLayout(new GridLayout(2, 2));
        final ChartPanel panel1 = new ChartPanel(chart1);
        final ChartPanel panel2 = new ChartPanel(chart2);
        final ChartPanel panel3 = new ChartPanel(chart3);
        final ChartPanel panel4 = new ChartPanel(chart4);
        this.add(panel1);
        this.add(panel2);
        this.add(panel3);
        this.add(panel4);
    }

    public static void main(final String[] args) {
        final JFrame frame = new JFrame("My Trip Driving From CA to FL...");
        final First chart = new First();
        frame.getContentPane().add(chart, BorderLayout.CENTER);
        frame.setSize(640, 480);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

}

如何显示标签JFreeChart的百分比值？

1 个答案: