java代码绘制验证码图片

 @RequestMapping(value = "/img")
    public void makeImage(HttpServletRequest request, HttpServletResponse response)
        throws IOException
    {

        int charNum = 4 ;
        int width = 20 * 3;
        int height = 28;

        //1.创建一张内存图片
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //2.获得绘图对象
        Graphics graphics = bufferedImage.getGraphics();

        //3.绘制背景颜色
        graphics.setColor(Color.WHITE);
        //graphics.fillRect(0,0,width,height);
        graphics.fill3DRect(0,0,width,height,true);
        //4.绘制图片边框
        graphics.setColor(Color.GRAY);
        graphics.drawRect(0,0,width-2,height-2);

        //5.输出验证码内容
        graphics.setColor(Color.RED);
        graphics.setFont(new Font("宋体",Font.BOLD,20));

        //6.随机输出4个字符
        String s = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";
        Random random = new Random();

        // session中要用到
        String msg = "";

        int x = 5;
        for (int i = 0; i < charNum; i++) {
            int index = random.nextInt(32);
            String content = String.valueOf(s.charAt(index));

            msg += content;
            graphics.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
            graphics.drawString(content, x, 22);
            x += 20;
        }

        // 6、绘制干扰线
        graphics.setColor(Color.GRAY);
        for (int i = 0; i < 5; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);

            int y1 = random.nextInt(height);
            int y2 = random.nextInt(height);
            graphics.drawLine(x1, y1, x2, y2);
        }

        // 释放资源
        graphics.dispose();

        // 图片输出 ImageIO
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());


    }