附：本文全部源代码

Listing E

＜ %@ page language="java" %＞
＜%@ page import="java.io.OutputStream" %＞
＜%@ page import="java.sql.*" %＞
＜%@ page import="java.awt.*" %＞
＜%@ page import="java.awt.geom.*" %＞
＜%@ page import="java.awt.image.BufferedImage" %＞
＜%@ page import="com.sun.image.codec.jpeg.*" %＞
＜%!
////////////////////////////////////////////////////////////
// PieColors class manages the colors used in the pie chart
////////////////////////////////////////////////////////////
class PieColors
{
　 Color pieColorArray[] = {
　　 new Color(210,60,60), new Color(60,210,60), new Color(60,60,210),
　　 new Color(120,60,120), new Color(60,120,210), new Color(210,120,60)
　　 };
　 int curPieColor = 0;
　 public Color getPieColor()
　 {
　　 return pieColorArray[curPieColor];
　 }
　 public void setNewColor()
　 {
　　 curPieColor++;
　　 if(curPieColor ＞= pieColorArray.length)
　　 {curPieColor = 0;}
　 }
}
%＞
＜%! String driver = "com.mysql.jdbc.Driver"; String dburl = "jdbc:mysql://localhost/articles"; String dbuid = "myuid"; String dbpwd = "mypwd";

////////////////////////////////////////////////////////////
// Get the products from the database as a String array
////////////////////////////////////////////////////////////
public String[] getProducts()
{
　 String[] arr = new String[0];
　 Connection con;
　 Statement stmt;
　 ResultSet rs;
　 int count = 0;
　 String sql = "select * from p_products order by productID";
　 try
　 {
　　 //Load Driver:
　　 Class.forName(driver);
　　 //Connect to the database with the url
　　 con = DriverManager.getConnection(dburl , dbuid , dbpwd);
　　 stmt = con.createStatement();
　　 //Get ResultSet
　　 rs = stmt.executeQuery(sql);
　　 //Count the records
　　 while(rs.next()){count++;
　 }
　 //Create an array of the correct size
　 arr = new String[count];
　 //Get ResultSet (the most portable way of using rs a second time)
　 rs = stmt.executeQuery(sql);
　 while(rs.next())
　 {
　　 arr[rs.getInt("productID")] = rs.getString("productname");
　 }
　 stmt.close();
　 con.close();
}
　 catch (java.lang.Exception ex)
　 {arr[0] = ex.toString();}
　 return arr;
}
////////////////////////////////////////////////////////////
//Get the sales totals from the database
////////////////////////////////////////////////////////////
public float[] getSales(int products)
{
　 float[] arr = new float[products];
　 Connection con;
　 Statement stmt;
　 ResultSet rs;
　 String sql = "select productID, amount from p_sales";
　 try {
　　 //Load Driver:
　　 Class.forName(driver);
　　 //Connect to the database with the url
　　 con = DriverManager.getConnection(dburl , dbuid , dbpwd);
　　 stmt = con.createStatement();
　　 //Get ResultSet
　　 rs = stmt.executeQuery(sql);
　　 while (rs.next()) { int product = rs.getInt("productID");
　　 //Check that the productID is valid
　　 if (product ＞= 0 && product ＜ products)
　　 {
　　　 //Add to product total
　　　 arr[product] += rs.getFloat("amount");
　　 }
　 }
　 stmt.close();
　 con.close();
} catch (java.lang.Exception ex) {arr[0] = -1.0f; }
　 return arr; } %＞
＜%
　 //get an array that contains the product names
　 String products[] = getProducts();
　 //read the data and store the totals in an array
　 float sales[] = getSales(products.length);
　 //Declare PieColors PieColors
　 pc = new PieColors();
　 //Colors Color
　 dropShadow = new Color(240,240,240);
　 //inner padding to make sure bars never touch the outer border
　 int innerOffset = 20;
　 //Set the graph's outer width & height
　 int WIDTH = 400;
　 int HEIGHT = 200;
　 int pieHeight = HEIGHT - (innerOffset * 2);
　 int pieWidth = pieHeight;
　 //To make a square (circular) pie
　 int halfWidth = WIDTH/2;
　 //Width of the inner graphable area
　 int innerWIDTH = WIDTH - (innerOffset * 2);
　 //graph dimensions Dimension
　 graphDim = new Dimension(WIDTH,HEIGHT);
　 Rectangle graphRect = new Rectangle(graphDim);
　 //border dimensions
　 Dimension borderDim = new Dimension(halfWidth-2,HEIGHT-2);
　 Rectangle borderRect = new Rectangle(borderDim);

　 /////////////////////////////////////////////////////////////
　 //Set up the graph
　 ////////////////////////////////////////////////////////////
　 //Set content type
　 response.setContentType("image/jpeg");
　 //Create BufferedImage & Graphics2D
　 BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
　 Graphics2D g2d = bi.createGraphics();
　 // Set Antialiasing RenderingHints
　 renderHints = new RenderingHints( RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
　 g2d.setRenderingHints(renderHints);
　 //Set graph background color to white:
　 g2d.setColor(Color.white);
　 g2d.fill(graphRect);
　 //Draw black border
　 g2d.setColor(Color.black);
　 borderRect.setLocation(1,1);
　 g2d.draw(borderRect);
　 //Now draw border for legend
　 borderRect.setLocation((WIDTH/2) + 1,1);
　 g2d.draw(borderRect); 　
　 ////////////////////////////////////////////////////////////////////
　 //Draw data onto the graph: 　　　
　 ////////////////////////////////////////////////////////////////////
　 int x_pie = innerOffset;
　 int y_pie = innerOffset; int border = 20;
　 //Main chart Ellipse
　 //Ellipse2D.Double el = new Ellipse2D.Double(x_pie, y_pie, pieWidth, pieHeight); 　Ellipse2D.Double elb = new Ellipse2D.Double(x_pie - border/2, y_pie - border/2, pieWidth + border, pieHeight + border);
　 //Shadow
　 g2d.setColor(dropShadow);
　 g2d.fill(elb);
　 //Border
　 g2d.setColor(Color.black);
　 g2d.draw(elb);