生成验证码的java类(未测试)

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

//验证码
public final class ImageUtil {
private static final String[] chars = { "0", "1", "2", "3", "4", "5", "6",
"7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "J", "K",
"L", "M", "N", "P" };
private static final int SIZE = 5;// 字符长度
private static final int LINES = 7;// 干扰线
private static final int WIDTH = 100;
private static final int HEIGHT = 50;
private static final int FONT_SIZE = 30;// 字体大小

public static Map<String, BufferedImage> createImage() {
StringBuffer sb = new StringBuffer();
BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
Graphics graphic = image.getGraphics();
graphic.setColor(Color.LIGHT_GRAY);
graphic.fillRect(0, 0, WIDTH, HEIGHT);
Random ran = new Random();
// 画随机字符
for (int i = 1; i <= SIZE; i++) {

int r = ran.nextInt(chars.length);
graphic.setColor(getRandomColor());
graphic.setFont(new Font(null, Font.BOLD + Font.ITALIC, FONT_SIZE));
graphic.drawString(chars[r], (i - 1) * WIDTH / SIZE, HEIGHT / 2);
sb.append(chars[r]);// 将字符保存，存入Session
}
// 画干扰线
for (int i = 1; i <= LINES; i++) {
graphic.setColor(getRandomColor());
graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
}
Map<String, BufferedImage> map = new HashMap<String, BufferedImage>();
map.put(sb.toString(), image);
return map;
}

public static Color getRandomColor() {
Random ran = new Random();
Color color = new Color(ran.nextInt(156), ran.nextInt(156),
ran.nextInt(156));
return color;
}
}