Java 生成随机验证码

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;

/**
* CodeImageGenerator.java
*
* @author <a href="mailto:[e-mail]">Andy Lu</a>
* @version 1.0
*/
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("codeImage.jpeg");
CodeImageGenerator cig = new CodeImageGenerator();
ImageIO.write(cig.getImage(), "JPEG", imgFile);
}
}