使用BufferedImage生成驗證碼(方法)

@RequestMapping("/imagecode")
    public void image(HttpServletRequest request, HttpServletResponse response, Model model) throws IOException, ServletException {
        //告訴客戶端不使用緩存
        response.setHeader("pragma", "no-cache");
        response.setHeader("cache-control", "no-cache");
        response.setIntHeader("expires", 0);

        //生成驗證碼圖片
        BufferedImage img = drawValidateCode(request);
        //將圖片對象以流的方式輸出的客戶端
        ServletOutputStream outputStream = response.getOutputStream();
        ImageIO.write(img, "jpg", response.getOutputStream());
        response.getOutputStream().close();
        //return "redirect:hello";
    }


private BufferedImage drawValidateCode(HttpServletRequest request){
        int width = 110;
        int height = 25;

        //在內存中創建一個圖片對象
        BufferedImage img = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

        //創建一個畫筆
        Graphics g = img.getGraphics();

        //給圖片添加顏色
        g.setColor(Color.PINK);  //設置一個顏色
        g.fillRect(1,1,width-2,height-2);  //填充顏色

        //給邊框一個色
        g.setColor(Color.RED);
        g.drawRect(0, 0, width - 1, height - 1);//設置邊框的顯示座標

        //設置文本樣式l
        g.setColor(Color.BLUE);
        g.setFont(new Font("宋體", Font.BOLD | Font.ITALIC, 15));

        //給圖片添加文本
        Random rand = new Random();
        String str = "";
        int position = 20;
        for (int i = 0; i < 4; i++) {
            int rd = rand.nextInt(10);
            str += rd;
            g.drawString(rd + "", position, 20); //給圖片填充文本
            position += 20;
        }

        //Session 中
        request.getSession().setAttribute("SESSION_IMAGE", str);
        //添加9條幹擾線
        for (int i = 0; i < 9; i++) {
            g.drawLine(rand.nextInt(width), rand.nextInt(height), rand.nextInt(width), rand.nextInt(height));
        }

        return img;
    }