public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        BufferedImage image = new BufferedImage(100, 100,                BufferedImage.TYPE_INT_RGB);        Graphics g = image.getGraphics();        // 1.设置背景色        setBackGround(g);        // 2.设置边框        setBorder(g);        // 3.画干扰线        drawRandomLine(g);        // 4.写随机数        drawRandomNum(g);        // 5.图形写给浏览器        response.setContentType("image/jpeg");        ImageIO.write(image, "jpg", response.getOutputStream());    }    private void drawRandomNum(Graphics g) {        g.setColor(Color.RED);        g.setFont(new Font("宋体",Font.BOLD,20));        //所有汉字区间 \u4e00 \u9fa5        for (int i = 0; i < 4; i++) {            int r=new Random().nextInt(100);            int r2=new Random().nextInt(100);            g.drawString("好", r, r2);        }    }    private void drawRandomLine(Graphics g) {        g.setColor(Color.GREEN);        for (int i = 0; i < 5; i++) {            int x1 = new Random().nextInt(100);            int y1 = new Random().nextInt(100);            int x2 = new Random().nextInt(100);            int y2 = new Random().nextInt(100);            g.drawLine(x1, y1, x2, y2);        }    }    private void setBorder(Graphics g) {        g.setColor(Color.BLUE);        g.drawRect(1, 1, 98, 98);    }    private void setBackGround(Graphics g) {        g.setColor(Color.WHITE);        g.fillRect(0, 0, 100, 100);    }