Java圖片驗證碼的生成與驗證

1.請求獲取驗證碼圖片的API

/**
 * Created with IntelliJ IDEA.
 * Description:
 *
 * @PROJECT_NAME: xxl-sso
 * @author: LiYong
 * @date: 2019-02-21 8:54
 */
@Controller
@RequestMapping("/api")
public class CaptchaController {
    /**
     * 用於生成帶四位數字驗證碼的圖片
     */
    @RequestMapping(value = "/captcha")
    @ResponseBody
    public String imagecode(HttpServletRequest request, HttpServletResponse response) throws Exception {
        response.setDateHeader("Expires", 0);
        response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
        response.addHeader("Cache-Control", "post-check=0, pre-check=0");
        response.setHeader("Pragma", "no-cache");
        response.setContentType("image/jpeg");

        OutputStream os = response.getOutputStream();
        //返回驗證碼和圖片的map
        Map<String,Object> map = Captcha.getImageCode(86, 37, os);
        String simpleCaptcha = "simpleCaptcha";
        request.getSession().setAttribute(simpleCaptcha, map.get("strEnsure").toString().toLowerCase());
        request.getSession().setAttribute("codeTime",new Date().getTime());
        try {
            ImageIO.write((BufferedImage) map.get("image"), "jpg", os);
        } catch (IOException e) {
            return "";
        }   finally {
            if (os != null) {
                os.flush();
                os.close();
            }
        }
        return null;
    }
}

2.驗證前端輸入的驗證碼API

/**
 * Created with IntelliJ IDEA.
 * Description:
 *
 * @PROJECT_NAME: xxl-sso
 * @author: LiYong
 * @date: 2019-02-21 8:56
 */
@Controller
@RequestMapping("/api")
public class VerifyController {
    /**
     * @param checkCode 前端用戶輸入返回的驗證碼
     * 參數若需要，自行添加
     */
    @RequestMapping(value = "/verify")
    @ResponseBody
    public String checkcode(HttpServletRequest request,
                            HttpSession session,
                            String checkCode) throws Exception {
        // 驗證碼有效時長爲1分鐘
        Date now = new Date();
        Long codeTime = Long.valueOf(session.getAttribute("codeTime") + "");
        // 獲得驗證碼對象
        Object cko = session.getAttribute("simpleCaptcha");
        if (cko == null) {
            request.setAttribute("errorMsg", "請輸入驗證碼！");
            return "請輸入驗證碼！";
        }
        String captcha = cko.toString();
        // 判斷驗證碼輸入是否正確
        if (StringUtils.isEmpty(checkCode) || captcha == null || !(checkCode.equalsIgnoreCase(captcha))) {
            request.setAttribute("errorMsg", "驗證碼錯誤！");
            return "驗證碼錯誤，請重新輸入！";
        } else if ((now.getTime() - codeTime) / 1000 / 60 > 1) {
            request.setAttribute("errorMsg", "驗證碼已失效，請重新輸入！");
            return "驗證碼已失效，請重新輸入！";
        } else {

            // 在這裏可以處理自己需要的事務，比如驗證登陸等

            return "驗證通過！";
        }
    }
}

3.工具類

/**
 * Created with IntelliJ IDEA.
 * Description:
 *
 * @PROJECT_NAME: xxl-sso
 * @author: LiYong
 * @date: 2019-02-21 8:56
 */
public class Captcha {
    private static char mapTable[] = {
            '0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', '0', '1',
            '2', '3', '4', '5', '6', '7',
            '8', '9'};
    public static Map<String, Object> getImageCode(int width, int height, OutputStream os) {
        Map<String,Object> returnMap = new HashMap<String, Object>();
        if (width <= 0) width = 60;
        if (height <= 0) height = 20;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 獲取圖形上下文
        Graphics g = image.getGraphics();
        //生成隨機類
        Random random = new Random();
        // 設定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        //設定字體
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        // 隨機產生168條幹擾線，使圖象中的認證碼不易被其它程序探測到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 168; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }
        //取隨機產生的碼
        String strEnsure = "";
        //4代表4位驗證碼,如果要生成更多位的認證碼,則加大數值
        for (int i = 0; i < 4; ++i) {
            strEnsure += mapTable[(int) (mapTable.length * Math.random())];
            // 將認證碼顯示到圖象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
            // 直接生成
            String str = strEnsure.substring(i, i + 1);
            // 設置隨便碼在背景圖圖片上的位置
            g.drawString(str, 13 * i + 20, 25);
        }
        // 釋放圖形上下文
        g.dispose();
        returnMap.put("image",image);
        returnMap.put("strEnsure",strEnsure);
        return returnMap;
    }
    //給定範圍獲得隨機顏色
    static Color getRandColor(int fc, int bc) {
        Random random = new Random();
        if (fc > 255) fc = 255;
        if (bc > 255) bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
}