数学图形验证码

1、生成图形验证码

public BufferedImage createVerifyCode(MiaoshaUser user, long goodsId) {

if (user ==null || goodsId <=0) {

return null;

    }

int width =80;

    int height =32;

    //create the image

    BufferedImage image =new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    Graphics g = image.getGraphics();

    // set the background color

    g.setColor(new Color(0xDCDCDC));

    g.fillRect(0, 0, width, height);

    // draw the border

    g.setColor(Color.black);

    g.drawRect(0, 0, width -1, height -1);

    // create a random instance to generate the codes

    Random rdm =new Random();

    // make some confusion

    for (int i =0; i <50; i++) {

int x = rdm.nextInt(width);

        int y = rdm.nextInt(height);

        g.drawOval(x, y, 0, 0);

    }

// 生成随机算式

    String verifyCode = generateVerifyCode(rdm);

    g.setColor(new Color(0, 100, 0));

    g.setFont(new Font("Candara", Font.BOLD, 24));

    g.drawString(verifyCode, 8, 24);

    g.dispose();

    //把验证码存到redis中

    int rnd =calc(verifyCode);

    redisService.set(MiaoshaKey.getMiaoshaVerifyCode, user.getId() +"," + goodsId, rnd);

    //输出图片

    return image;

}

2、生成数学公式

private static char[]ops =new char[]{'+', '-', '*'};

/**

* + - *

*/

private String generateVerifyCode(Random rdm) {

int num1 = rdm.nextInt(10);

    int num2 = rdm.nextInt(10);

    int num3 = rdm.nextInt(10);

    char op1 =ops[rdm.nextInt(3)];

    char op2 =ops[rdm.nextInt(3)];

    String exp ="" + num1 + op1 + num2 + op2 + num3;

    return exp;

}

3、计算数学公式

private static int calc(String exp) {

try {

ScriptEngineManager manager =new ScriptEngineManager();

        ScriptEngine engine = manager.getEngineByName("JavaScript");

        return (Integer) engine.eval(exp);

    }catch (Exception e) {

e.printStackTrace();

        return 0;

    }

}

4、controller层返回

@RequestMapping("/verifyCode")

@ResponseBody

public ResultgetMiaoshaVerifyCode(HttpServletResponse response,Model model,

      MiaoshaUser user, @RequestParam("goodsId")long goodsId) {

if (user ==null) {

return Result.error(CodeMsg.SESSION_ERROR);

    }

BufferedImage image =miaoshaService.createVerifyCode(user,goodsId);

    try {

OutputStream outputStream = response.getOutputStream();

        ImageIO.write(image,"JPEG",outputStream);

        outputStream.flush();

        outputStream.close();

return null;

    }catch (IOException e) {

e.printStackTrace();

        return Result.error(CodeMsg.MIAOSHA_FAIL);

    }

}