工具类：随机生成图片和颜色-蒲公英云

工具类：随机生成图片和颜色

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;
public class CodeUtil {
    private static final String[] chars = {
    "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c"};
    private static final int SIZE = 4;
    private static final int LINES = 8;
    private static final int WIDTH = 55;
    private static final int HEIGHT = 25;
    private static final int FONT_SIZE = 16;
    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.WHITE);
        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 = 2; 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(256), ran.nextInt(256), ran.nextInt(256));
        return color;
    }
    public static void main(String[] args) {
        Map<String, BufferedImage> image = createImage();
        System.out.println(image);
        Color randomColor = getRandomColor();
        System.out.println(randomColor);
    }
}