[ Java 常見問題 ] JFreeChart : Retrieve data from mouse click on graph

Preface: 
這邊要講解, 如何透過在 JFreeChart 產生的 Chart 圖表上, 點擊圖表並獲得特定區域的資料. 這邊會以 PieChart3DDemo3 當作範例. 

Sample Code: 
在 PieChart3DDemo3 的執行結果會得到下面的 PieChart 圖表, 而我們的加 code 讓你在Pie 圖表特定區塊上點擊滑鼠後, 跳出視窗顯示點擊區域的主題: 
 

其實只要在 ChartPanel 加上 ChartMouseListener 如下: 

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1. chartpanel.addChartMouseListener(new ChartMouseListener(){  
2.     public void chartMouseClicked(ChartMouseEvent e){  
3.         PieSectionEntity entity = (PieSectionEntity)e.getEntity();  
4.         System.out.println(entity.getSectionKey());  
5.         JOptionPane.showConfirmDialog(null, entity.getSectionKey(), "Info", JOptionPane.CLOSED_OPTION, JOptionPane.INFORMATION_MESSAGE);  
6.     }  
7.     public void chartMouseMoved(ChartMouseEvent e){  
8.         //[...do something on move...]  
9.     }  
10. });  

如此你在 Java 區域點擊便會得到對應 Key 值的 Popup 如下: 
 

完整代碼如下: 

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1. package piecharts;  
2.   
3. import java.awt.Dimension;  
4. import java.text.AttributedString;  
5.   
6. import javax.swing.JOptionPane;  
7. import javax.swing.JPanel;  
8.   
9. import org.jfree.chart.ChartFactory;  
10. import org.jfree.chart.ChartMouseEvent;  
11. import org.jfree.chart.ChartMouseListener;  
12. import org.jfree.chart.ChartPanel;  
13. import org.jfree.chart.JFreeChart;  
14. import org.jfree.chart.entity.PieSectionEntity;  
15. import org.jfree.chart.labels.PieSectionLabelGenerator;  
16. import org.jfree.chart.plot.PiePlot3D;  
17. import org.jfree.data.general.DefaultPieDataset;  
18. import org.jfree.data.general.PieDataset;  
19. import org.jfree.ui.ApplicationFrame;  
20. import org.jfree.ui.RefineryUtilities;  
21. import org.jfree.util.Rotation;  
22.   
23. public class PieChart3DDemo3 extends ApplicationFrame {  
24.     static class CustomLabelGenerator implements PieSectionLabelGenerator {  
25.   
26.         public String generateSectionLabel(PieDataset piedataset,  
27.                 Comparable comparable) {  
28.             String s = null;  
29.             if (piedataset != null && !comparable.equals("PHP"))  
30.                 s = comparable.toString();  
31.             return s;  
32.         }  
33.   
34.         public AttributedString generateAttributedSectionLabel(  
35.                 PieDataset piedataset, Comparable comparable) {  
36.             return null;  
37.         }  
38.   
39.         CustomLabelGenerator() {  
40.         }  
41.     }  
42.   
43.     public PieChart3DDemo3(String s) {  
44.         super(s);  
45.         PieDataset piedataset = createDataset();  
46.         JFreeChart jfreechart = createChart(piedataset);  
47.         ChartPanel chartpanel = new ChartPanel(jfreechart);  
48.         chartpanel.setPreferredSize(new Dimension(500, 270));  
49.         chartpanel.addChartMouseListener(new ChartMouseListener(){  
50.             public void chartMouseClicked(ChartMouseEvent e){  
51.                 PieSectionEntity entity = (PieSectionEntity)e.getEntity();  
52.                 System.out.println(entity.getSectionKey());  
53.                 JOptionPane.showConfirmDialog(null, entity.getSectionKey(), "Info", JOptionPane.CLOSED_OPTION, JOptionPane.INFORMATION_MESSAGE);  
54.             }  
55.             public void chartMouseMoved(ChartMouseEvent e){  
56.                 //[...do something on move...]  
57.             }  
58.         });  
59.         setContentPane(chartpanel);  
60.     }  
61.   
62.     private static PieDataset createDataset() {  
63.         DefaultPieDataset defaultpiedataset = new DefaultPieDataset();  
64.         defaultpiedataset.setValue("Java", new Double(43.200000000000003D));  
65.         defaultpiedataset.setValue("Visual Basic", new Double(10D));  
66.         defaultpiedataset.setValue("C/C++", new Double(17.5D));  
67.         defaultpiedataset.setValue("PHP", new Double(32.5D));  
68.         defaultpiedataset.setValue("Perl", new Double(1.0D));  
69.         return defaultpiedataset;  
70.     }  
71.   
72.     private static JFreeChart createChart(PieDataset piedataset) {  
73.         JFreeChart jfreechart = ChartFactory.createPieChart3D(  
74.                 "Pie Chart 3D Demo 3", piedataset, true, true, false);  
75.         PiePlot3D pieplot3d = (PiePlot3D) jfreechart.getPlot();  
76.         pieplot3d.setStartAngle(290D);  
77.         pieplot3d.setDirection(Rotation.CLOCKWISE);  
78.         pieplot3d.setForegroundAlpha(0.5F);  
79.         pieplot3d.setNoDataMessage("No data to display");  
80.         pieplot3d.setLabelGenerator(new CustomLabelGenerator());  
81.         return jfreechart;  
82.     }  
83.   
84.     public static JPanel createDemoPanel() {  
85.         JFreeChart jfreechart = createChart(createDataset());  
86.         return new ChartPanel(jfreechart);  
87.     }  
88.   
89.     public static void main(String args[]) {  
90.         PieChart3DDemo3 piechart3ddemo3 = new PieChart3DDemo3(  
91.                 "JFreeChart: PieChart3DDemo3.java");  
92.         piechart3ddemo3.pack();  
93.         RefineryUtilities.centerFrameOnScreen(piechart3ddemo3);  
94.         piechart3ddemo3.setVisible(true);  
95.     }  
96. }  

Supplement: 
* Stackoverflow : JFreeChart - obtain data source value on mouse click