java随机生成验证码

package com.yuyuchen.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;

public final class ImageUtil {
    
    // 验证码字符集
    private static final char[] chars = { 
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 
        'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
    // 字符数量
    private static final int SIZE = 4;
    // 干扰线数量
    private static final int LINES = 5;
    // 宽度
    private static final int WIDTH = 80;
    // 高度
    private static final int HEIGHT = 40;
    // 字体大小
    private static final int FONT_SIZE = 30;

    /**
     * 生成随机验证码及图片
     */
    public static Object[] createImage() {
        StringBuffer sb = new StringBuffer();
        // 1.创建空白图片
        BufferedImage image = new BufferedImage(
            WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        // 2.获取图片画笔
        Graphics graphic = image.getGraphics();
        // 3.设置画笔颜色
        graphic.setColor(Color.LIGHT_GRAY);
        // 4.绘制矩形背景
        graphic.fillRect(0, 0, WIDTH, HEIGHT);
        // 5.画随机字符
        Random ran = new Random();
        for (int i = 0; i <SIZE; i++) {
            // 取随机字符索引
            int n = ran.nextInt(chars.length);
            // 设置随机颜色
            graphic.setColor(getRandomColor());
            // 设置字体大小
            graphic.setFont(new Font(
                null, Font.BOLD + Font.ITALIC, FONT_SIZE));
            // 画字符
            graphic.drawString(
                chars[n] + "", i * WIDTH / SIZE, HEIGHT / 2);
            // 记录字符
            sb.append(chars[n]);
        }
        // 6.画干扰线
        for (int i = 0; i < LINES; i++) {
            // 设置随机颜色
            graphic.setColor(getRandomColor());
            // 随机画线
            graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
                    ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
        }
        // 7.返回验证码和图片
        return new Object[]{sb.toString(), image};
    }

    /**
     * 随机取色
     */
    public static Color getRandomColor() {
        Random ran = new Random();
        Color color = new Color(ran.nextInt(256), 
                ran.nextInt(256), ran.nextInt(256));
        return color;
    }
    
    public static void main(String[] args) throws IOException {
        Object[] objs = createImage();
        BufferedImage image = (BufferedImage) objs[1];
        OutputStream os = new FileOutputStream("d:/1.jpg");
        ImageIO.write(image, "jpeg", os);
        os.close();
    }

}