[java] 验证码生成

public class ValidImageUtils {

    private static String codeChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机码
    private static String url = "H:\\files\\graph";//图片保存的服务器路径

    public static ValidImage generateGraph()throws IOException{
        // 获得验证码集合的长度
        int charsLength = codeChars.length();

        // 设置图形验证码的长和宽
        int width = 90, height = 30;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        Random random = new Random();
        g.setColor(getRandomColor(180, 250));
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.ITALIC, height));
        g.setColor(getRandomColor(120, 180));

        // 用户保存最后随机生成的验证码
        StringBuffer validationCode = new StringBuffer();
        // 验证码的随机字体
        String[] fontNames = {"Times New Roman", "Book antiqua", "Arial"};
        // 随机生成4个验证码
        for (int i = 0; i < 4; i++) {
            // 随机设置当前验证码的字符的字体
            g.setFont(new Font(fontNames[random.nextInt(3)], Font.ITALIC,
                    height));
            // 随机获得当前验证码的字符
            char codeChar = codeChars.charAt(random.nextInt(charsLength));
            validationCode.append(codeChar);
            // 随机设置当前验证码字符的颜色
            g.setColor(getRandomColor(10, 100));
            // 在图形上输出验证码字符，x和y都是随机生成的
            g.drawString(String.valueOf(codeChar), 16 * i + random.nextInt(7),
                    height - random.nextInt(6));
        }

        //todo 此为验证码数字表示

        //todo 此为验证码图片url地址
        String finalurl = UUID.randomUUID().toString();

        finalurl = url + "\\" + finalurl + ".jpg";

        //将图片存入服务器文件中
        System.out.println(finalurl);
        FileOutputStream fos = new FileOutputStream(new File(finalurl));
        ImageIO.write(image, "JPEG", fos);
        fos.flush();
        fos.close();


        ValidImage validImage=new ValidImage(validationCode.toString(),finalurl);
        return validImage;
    }
    private static Color getRandomColor(int minColor, int maxColor) {
        Random random = new Random();
        if (minColor > 255) {
            minColor = 255;
        }
        if (maxColor > 255) {
            maxColor = 255;
        }
        //获得r的随机颜色值
        int red = minColor + random.nextInt(maxColor - minColor);
        int green = minColor + random.nextInt(maxColor - minColor);
        int blue = minColor + random.nextInt(maxColor - minColor);
        return new Color(red, green, blue);
    }


}