String code = RandomUtil.randomString(BASE_CHECK_CODES,4);
String lowerCaseCode = code.toLowerCase();
String realKey = MD5Util.MD5Encode(lowerCaseCode+key,"utf-8");
//存redis
redisUtil.set(realKey,lowerCaseCode,60);
//获取验证码照片
String base64 = RandImageUtil.generate(code);
res.setSuccess(true);
res.setResult(base64);

//RandImageUtil主要是这句产生随机验证码图片
BufferedImage image = getImageBuffer(resultCode);

private static BufferedImage getImageBuffer(String resultCode){
        // 在内存中创建图象
        final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        final Graphics2D graphics = (Graphics2D) image.getGraphics();
        // 设定背景颜色
        graphics.setColor(Color.WHITE); // ---1
        // 填充矩形
        graphics.fillRect(0, 0, width, height);
        // 设定边框颜色
        // graphics.setColor(getRandColor(100, 200)); // ---2
        graphics.drawRect(0, 0, width - 1, height - 1);

        final Random random = new Random();
        // 随机产生干扰线，使图象中的认证码不易被其它程序探测到
        for (int i = 0; i < count; i++) {
            graphics.setColor(getRandColor(150, 200)); // ---3

            final int x = random.nextInt(width - lineWidth - 1) + 1; // 保证画在边框之内
            final int y = random.nextInt(height - lineWidth - 1) + 1;
            final int xl = random.nextInt(lineWidth);
            final int yl = random.nextInt(lineWidth);
            graphics.drawLine(x, y, x + xl, y + yl);
        }
        // 取随机产生的认证码
        for (int i = 0; i < resultCode.length(); i++) {
            // 将认证码显示到图象中,调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            // graphics.setColor(new Color(20 + random.nextInt(130), 20 + random
            // .nextInt(130), 20 + random.nextInt(130)));
            // 设置字体颜色
            graphics.setColor(Color.BLACK);
            // 设置字体样式
            // graphics.setFont(new Font("Arial Black", Font.ITALIC, 18));
            graphics.setFont(new Font("Times New Roman", Font.BOLD, 24));
            // 设置字符，字符间距，上边距
            graphics.drawString(String.valueOf(resultCode.charAt(i)), (23 * i) + 8, 26);
        }
        // 图象生效
        graphics.dispose();
        return image;
}