一個簡單的繪制餅圖的 Java Bean 實例

import java.awt.*;

/**

Simple charting bean. This version just draws a Pie Chart.
*
It doesn't even label the pie slices; that is left as a
(non-trivial) exercise for the reader. Please read the
Technical Report "How Hard can it be to draw Pie Charts?" by Chris
van Wyck, Purdue/Bell Labs, 1989??, before you decide how easy
the work is going to be!
*/
public class ChartBean extends Component {
/* The title to print on the chart /
protected String title;
/* the data to draw /
protected ChartData data[];
/* degrees in a circle /
public static final int CIRCLE = 360;
/* a set of colors to draw the pies in /
protected Color[] colors = {
   Color.red,
   Color.blue,
   Color.green,
   Color.pink,
   Color.orange
};
/ Construct a ChartBean with a title */
public ChartBean(String s) {
   title = s;
   setBackground(Color.white);
}
/ Construct a ChartBean with no title (no-arg constructor

required for Beans).
*/
public ChartBean() {
 this(null);
}

public void setLabel(String s) {
   title = s;
}
public String getLabel() {
   return title;
}
public void setData(ChartData[] newStuff) {
   data = newStuff;
   repaint();
}
public void paint(Graphics g) {
   Dimension sz = getSize();
   int w = sz.width, h = sz.width;
if (title != null)

  g.drawString(title, w/10, (int)(h*.9));


if (data == null || data.length == 0) {

  g.drawOval(0, 0, w, h);
  g.drawString("Please provide some data!", w/10, h/2);
  return;

}
int total = 0;
   int angle = 0;
   int rad = 0;   // "radians" (actually degrees) to draw
   int colNum = 0;
for (int i=0; i<data.length; i++)

  total += data[i].value;

for (int i=0; i<data.length; i++) {

  rad = (int)(CIRCLE * ((float)data[i].value / (float)total));
  // System.out.println("data: "+data[i].name+";"+data[i].value+
  //   ",rad="+rad);
  g.setColor(colors[colNum++]);
  colNum%=colors.length;   // keep it in bounds
  g.fillArc(0, 0, w, h, angle, rad);
  angle += rad;

}
}
public Dimension getMinimumSize() {
   return new Dimension(100, 120);
}
public Dimension getPreferredSize() {
   return new Dimension(200, 240);
}
}</pre>