Java随机生成验证码图片

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.Random;

import javax.imageio.ImageIO;

public final class CodeImageGenerator {
    private final static int DEF_WIDTH = 60;
    private final static int DEF_HEIGHT = 20;
    
    private String code;
    private int width;
    private int height;    
    private BufferedImage image;
    
    public CodeImageGenerator() {
        this(DEF_WIDTH, DEF_HEIGHT);
    }
    
    public CodeImageGenerator(int width, int height) {
        this.width = width;
        this.height = height;
        generateCodeImage();
    }
    
    private void generateCodeImage() {        
        // create the image
        image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);       
        Graphics g = image.getGraphics();
        
        // set the background color        
        g.setColor(new Color(0xDCDCDC));    
        g.fillRect(0, 0, width, height);
        
        // draw the border
        g.setColor(Color.black);
        g.drawRect(0, 0, width - 1, height - 1);
        
        // set the font
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

        // create a random instance to generate the codes
        Random random = new Random();
        
        // make some confusion
        for (int i = 0; i < 50; i++) { 
            int x = random.nextInt(width); 
            int y = random.nextInt(height);
            g.drawOval(x, y, 0, 0);
        }
        
        // generate a random code
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            code += rand;
            g.drawString(rand, 13*i+6, 16);
        }
        
        g.dispose();
    }
    
    public BufferedImage getImage() {
        return image;
    }
    
    public String getCode() {
        return code;
    }
    
    public static void main(String[] args) throws Exception {
        File imgFile = new File("D:\\codeImage1.jpeg");
        CodeImageGenerator cig = new CodeImageGenerator();
        ImageIO.write(cig.getImage(), "JPEG", imgFile);
    }
}