[ Java 代碼範本 ] JFreeChart : PieChart - Demo 4 (旋轉的圓餅圖)

前言 :
這裡要建立一個旋轉的 PieChart, 關鍵在於使用 javax.swing.Timer 搭配 javax.awt.event.ActionListener 建立的內部類別 Rotator 動態改變 Pie Chart 的角度, 使效果就像 Pie Chart 在旋轉. 而 PieChart 使用的資料容器為 PieDataset 而建立圖表方法為 createPieChart().

範例代碼 :
使用Packages : jcommon-1.0.16.jar, jfreechart-1.0.13.jar.

- PieChartDemo4.java :

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1. package john.jfreechart.piechart;  
2.   
3. import java.awt.Color;  
4. import java.awt.event.ActionEvent;  
5. import java.awt.event.ActionListener;  
6. import java.text.NumberFormat;  
7. import javax.swing.Timer;  
8. import org.jfree.chart.ChartFactory;  
9. import org.jfree.chart.ChartPanel;  
10. import org.jfree.chart.JFreeChart;  
11. import org.jfree.chart.labels.StandardPieSectionLabelGenerator;  
12. import org.jfree.chart.plot.PiePlot;  
13. import org.jfree.data.general.DefaultPieDataset;  
14. import org.jfree.data.general.PieDataset;  
15. import org.jfree.ui.ApplicationFrame;  
16. import org.jfree.ui.RefineryUtilities;  
17.   
18. /** 
19. * Source : http://www.koders.com/java/fidCA9ADCF38E1E1B2825657905E9A4FC95579E0E6B.aspx 
20. * @author John-Lee 
21. */  
22. public class PieChartDemo4 extends ApplicationFrame{  
23.   
24.     /** 
25.      * Default constructor. 
26.      * 
27.      * @param title  the frame title. 
28.      */  
29.     public PieChartDemo4(String title) {  
30.   
31.         super(title);  
32.         PieDataset dataset = createDataset(14);  
33.   
34.         // create the chart...  
35.         JFreeChart chart = ChartFactory.createPieChart(  
36.             "Pie Chart Demo 4",  // chart title  
37.             dataset,             // dataset  
38.             false,                // include legend  
39.             true,  
40.             false  
41.         );  
42.   
43.         // set the background color for the chart...  
44.         chart.setBackgroundPaint(new Color(222, 222, 255));  
45.         PiePlot plot = (PiePlot) chart.getPlot();  
46.         plot.setBackgroundPaint(Color.white);  
47.         plot.setCircular(true);  
48.         // For the label format, use {0} where the pie section key should be inserted, {1}   
49.         // for the absolute section value and {2} for the percent amount of the pie section,   
50.         // e.g. "{0} = {1} ({2})" will display as apple = 120 (5%).  
51.         plot.setLabelGenerator(new StandardPieSectionLabelGenerator("{0} = {2}"));  
52.         plot.setNoDataMessage("No data available");  
53.   
54.         // add the chart to a panel...  
55.         ChartPanel chartPanel = new ChartPanel(chart);  
56.         chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));  
57.         setContentPane(chartPanel);  
58.           
59.         Rotator rotator = new Rotator(plot);  
60.         rotator.start();  
61.   
62.     }  
63.   
64.     /** 
65.      * Creates a sample dataset. 
66.      *  
67.      * @param sections  the number of sections. 
68.      *  
69.      * @return A sample dataset. 
70.      */  
71.     private PieDataset createDataset(int sections) {  
72.         DefaultPieDataset result = new DefaultPieDataset();  
73.         for (int i = 0; i < sections; i++) {  
74.             double value = 100.0 * Math.random();  
75.             result.setValue("Section " + i, value);  
76.         }  
77.         return result;  
78.     }  
79.       
80.     /** 
81.      * Starting point for the demonstration application. 
82.      * 
83.      * @param args  ignored. 
84.      */  
85.     public static void main(String[] args) {          
86.         PieChartDemo4 demo = new PieChartDemo4("Pie Chart Demo 4");  
87.         demo.pack();  
88.         RefineryUtilities.centerFrameOnScreen(demo);  
89.         demo.setVisible(true);  
90.   
91.     }  
92.   
93.     /** 
94.      * The rotator. 
95.      * 
96.      * @author David Gilbert 
97.      */  
98.     static class Rotator extends Timer implements ActionListener {  
99.   
100.         /** The plot. */  
101.         private PiePlot plot;  
102.   
103.         /** The angle. */  
104.         private int angle = 270;  
105.   
106.         /** 
107.          * Constructor. 
108.          * 
109.          * @param plot  the plot. 
110.          */  
111.         Rotator(PiePlot plot) {  
112.             super(100, null);  
113.             this.plot = plot;  
114.             addActionListener(this); // every 100ms, trigger self.  
115.         }  
116.   
117.         /** 
118.          * Modifies the starting angle. 
119.          * Ref: 
120.          *  - javax.swing.Timer : http://download.oracle.com/javase/6/docs/api/javax/swing/Timer.html 
121.          *  - javax.awt.event.ActionListener : http://download.oracle.com/javase/6/docs/api/java/awt/event/ActionListener.html   
122.          * @param event  the action event. 
123.          */  
124.         public void actionPerformed(ActionEvent event) {  
125.             this.plot.setStartAngle(angle);  
126.             this.angle = this.angle + 1;  
127.             if (this.angle == 360) {  
128.                 this.angle = 0;  
129.             }  
130.         }  
131.     }  
132. }  

執行結果 :

This message was edited 5 times. Last update was at 02/06/2011 18:05:26