[ Java 代碼範本 ] JFreeChart : MultiplePieChart - Demo 1 (多維度的圓餅圖)

前言 : 
考慮如果你要表達不同區域的每季的營業額, 而每個圓餅圖代表著一個區域. 這時你便需要不只一個圓餅圖來呈現你的圖表. 這理要介紹如何實現多維度的圓餅圖. 首先你的資料將會以二維的陣列來表達, 並透過容器 CategoryDataset 來存放你的資料與對應的 label. 而在建立該容器可透過 DatasetUtilities 的方法 [])]createCategoryDataset() 來完成. 有了資料, 接下來便是圖表的建立. 透過 ChartFactory 的方法 createMultiplePieChart() 來建立多維度圓餅圖的圖表. 

範例代碼 : 
底下為建立 多維度圓餅圖的範例代碼, 當中也介紹如何修改圖表 Label 的字型與大小與 Label 顯示的內容. 

- MultiplePieChartDemo1.java :

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1. package john.jfreechart.piechart;  
2.   
3. import java.awt.Font;  
4.   
5. import org.jfree.chart.ChartFactory;  
6. import org.jfree.chart.ChartPanel;  
7. import org.jfree.chart.JFreeChart;  
8. import org.jfree.chart.labels.StandardPieSectionLabelGenerator;  
9. import org.jfree.chart.plot.MultiplePiePlot;  
10. import org.jfree.chart.plot.PiePlot;  
11. import org.jfree.data.category.CategoryDataset;  
12. import org.jfree.data.general.DatasetUtilities;  
13. import org.jfree.ui.ApplicationFrame;  
14. import org.jfree.ui.RefineryUtilities;  
15. import org.jfree.util.TableOrder;  
16.   
17. /** 
18. * A simple demonstration application showing how to create a chart consisting of multiple 
19. * pie charts. 
20. * @author John-Lee 
21. * 
22. */  
23. public class MultiplePieChartDemo1 extends ApplicationFrame {  
24.   
25.     /** 
26.      * Creates a new demo. 
27.      * 
28.      * @param title  the frame title. 
29.      */  
30.     public MultiplePieChartDemo1(String title) {  
31.   
32.         super(title);  
33.         CategoryDataset dataset = createDataset();  
34.         JFreeChart chart = createChart(dataset);  
35.         ChartPanel chartPanel = new ChartPanel(chart, true, true, true, false, true);  
36.         chartPanel.setPreferredSize(new java.awt.Dimension(650, 400));  
37.         setContentPane(chartPanel);  
38.   
39.     }  
40.       
41.     /** 
42.      * Creates a sample dataset. 
43.      *  
44.      * @return A sample dataset. 
45.      */  
46.     private CategoryDataset createDataset() {  
47.         double[][] data = new double[][] {  
48.             {3.0, 4.0, 3.0, 5.0},  
49.             {5.0, 7.0, 6.0, 8.0},  
50.             {5.0, 7.0, 3.0, 8.0},  
51.             {1.0, 2.0, 3.0, 4.0},  
52.             {2.0, 3.0, 2.0, 3.0}  
53.         };  
54.         CategoryDataset dataset = DatasetUtilities.createCategoryDataset(  
55.             "Region ", // rowKeyPrefix (Index of different PieCharts)  
56.             "Sales/Q", // columnKeyPrefix (Index of PieChart's content)  
57.             data  
58.         );  
59.         return dataset;  
60.     }  
61.       
62.     /** 
63.      * Creates a sample chart with the given dataset. 
64.      *  
65.      * @param dataset  the dataset. 
66.      *  
67.      * @return A sample chart. 
68.      */  
69.     private JFreeChart createChart(CategoryDataset dataset) {  
70.         JFreeChart chart = ChartFactory.createMultiplePieChart(  
71.             "Multiple Pie Chart",  // chart title  
72.             dataset,               // dataset  
73.             TableOrder.BY_ROW,  
74.             true,                  // include legend  
75.             true,  
76.             false  
77.         );  
78.         MultiplePiePlot plot = (MultiplePiePlot) chart.getPlot();  
79.         JFreeChart subchart = plot.getPieChart();  
80.         PiePlot p = (PiePlot) subchart.getPlot();  
81.         p.setLabelGenerator(new StandardPieSectionLabelGenerator("{0}"));  
82.         p.setLabelFont(new Font("SansSerif", Font.PLAIN, 10));  
83.         // This controls the space between the edges of the pie plot and the plot area itself   
84.         //(the region where the section labels appear).  
85.         //p.setInteriorGap(0.03);   
86.           
87.         return chart;  
88.     }  
89.       
90.     /** 
91.      * Starting point for the demonstration application. 
92.      * 
93.      * @param args  ignored. 
94.      */  
95.     public static void main(String[] args) {  
96.         MultiplePieChartDemo1 demo = new MultiplePieChartDemo1("Multiple Pie Chart Demo 1");  
97.         demo.pack();  
98.         RefineryUtilities.centerFrameOnScreen(demo);  
99.         demo.setVisible(true);  
100.   
101.     }  
102. }  

執行結果 :