服務器開發之圖形驗證碼

驗證碼

驗證碼是一種區分用戶是計算機還是人的公共全自動程序。短時間是無法退出人類舞臺的，目前只是盡量提升用戶體驗。

作用

• 賬號安全

• 反作弊

• 反爬蟲

• 防論壇灌水

• 防惡意注冊

分類

• 圖形驗證碼

• Gif動畫驗證碼

• 手機短信驗證碼

• 手機語音驗證碼

• 視頻驗證碼

• web2.0驗證碼

kaptcha驗證碼組件

簡介

kaptcha 是一個非常實用的驗證碼生成工具。有了它，你可以生成各種樣式的驗證碼，因為它是可配置的。

常見配置

• 驗證碼的字體

• 驗證碼字體的大小

• 驗證碼字體的字體顏色

• 驗證碼內容的范圍(數字，字母，中文漢字！)

• 驗證碼圖片的大小，邊框，邊框粗細，邊框顏色

• 驗證碼的干擾線(可以自己繼承com.google.code.kaptcha.NoiseProducer寫一個自定義的干擾線)

• 驗證碼的樣式(魚眼樣式、3D、普通模糊……當然也可以繼承com.google.code.kaptcha.GimpyEngine自定義樣式)

maven

<dependency>
    <groupId>com.github.axet</groupId>
    <artifactId>kaptcha</artifactId>
    <version>0.0.9</version>
</dependency>

kaptcha.properties

kaptcha.textproducer.font.color=red
kaptcha.image.width=130
kaptcha.image.height=44
kaptcha.textproducer.font.size=35
kaptcha.textproducer.char.length=4
kaptcha.textproducer.font.names=\\u5B8B\\u4F53,\\u6977\\u4F53,\\u5FAE\\u8F6F\\u96C5\\u9ED1
kaptcha.noise.color=gray
kaptcha.obscurificator.impl=com.google.code.kaptcha.impl.WaterRipple

代碼具體實現

本代碼主要用filter過濾器來生成驗證碼。

web.xml

<filter>
    <filter-name>KaptchaFilter</filter-name>
    <filter-class>com.xxoo.admin.ui.filter.KaptchaFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>KaptchaFilter</filter-name>
    <url-pattern>/kaptcha.jpg</url-pattern>
</filter-mapping>

注意：驗證碼過濾器需要放到Shiro之后,因為Shiro將包裝HttpSession.如果不,可能造成兩次的sesisonid不一樣。

圖片驗證碼類

public class CaptchaService {

    private static ImageCaptchaService instance = null;

    static {
        instance = new KaptchaImageCaptchaService();
    }

    public synchronized static ImageCaptchaService getInstance() {
        return instance;
    }

    public synchronized static boolean validate(HttpServletRequest httpServletRequest, String input) throws Exception {
        String text = instance.getText(httpServletRequest);
        boolean result = text.equalsIgnoreCase(input);
        instance.removeKaptcha(httpServletRequest);
        return result;
    }
}

基于Kaptcha的驗證碼圖片實現

public class KaptchaImageCaptchaService implements ImageCaptchaService {

    private Logger logger = LoggerFactory.getLogger(getClass());

    public KaptchaImageCaptchaService() {
    }

    public static Config getConfig() throws IOException {
        Properties p = new Properties();
        p.load(new DefaultResourceLoader().getResource("kaptcha.properties").getInputStream());
        Config config = new Config(p);
        return config;
    }

    @Override
    public void create(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        httpServletResponse.setDateHeader("Expires", 0L);
        httpServletResponse.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
        httpServletResponse.addHeader("Cache-Control", "post-check=0, pre-check=0");
        httpServletResponse.setHeader("Pragma", "no-cache");
        httpServletResponse.setContentType("image/jpeg");
        Config config = getConfig();
        Producer producer = config.getProducerImpl();
        String capText = producer.createText();
        if(logger.isDebugEnabled()){
            logger.info("create captcha:" + capText + ":" + config.getSessionKey() );
        }
        httpServletRequest.getSession().setAttribute(config.getSessionKey(), capText);
        httpServletRequest.getSession().setAttribute(config.getSessionDate(), new Date());
        BufferedImage bi = producer.createImage(capText);
        ServletOutputStream out = httpServletResponse.getOutputStream();
        ImageIO.write(bi, "jpg", out);
        out.flush();
        out.close();
    }

    @Override
    public String getText(HttpServletRequest httpServletRequest) throws Exception {
        return (String)httpServletRequest.getSession().getAttribute(getConfig().getSessionKey());
    }

    @Override
    public void removeKaptcha(HttpServletRequest httpServletRequest) throws Exception {
        httpServletRequest.getSession().removeAttribute(getConfig().getSessionKey());
        httpServletRequest.getSession().removeAttribute(getConfig().getSessionDate());
    }

}

驗證碼工具類

public class CaptchaService {

    private static ImageCaptchaService instance = null;

    static {
        instance = new KaptchaImageCaptchaService();
    }

    public synchronized static ImageCaptchaService getInstance() {
        return instance;
    }

    public synchronized static boolean validate(HttpServletRequest httpServletRequest, String input) throws Exception {
        String text = instance.getText(httpServletRequest);
        boolean result = text.equalsIgnoreCase(input);
        instance.removeKaptcha(httpServletRequest);
        return result;
    }
}

生成驗證碼過濾器

public class KaptchaFilter extends OncePerRequestFilter {

    private Logger logger = LoggerFactory.getLogger(getClass());

    @Override
    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        try {
            CaptchaService.getInstance().create(httpServletRequest,httpServletResponse);
        } catch (Exception e) {
            logger.info("create captcha error.",e);
        }
    }

}

驗證碼校驗

private boolean doCaptchaValidate(HttpServletRequest request, String code) {
        //比對
        try {
            if (code == null || !CaptchaService.validate(request, code)) {
                return false;
            } else {
                return true;
            }
        } catch (Exception e) {
            logger.warn("captcha check error！");
            return false;
        }
}

小結

本文主要講述了kaptcha圖形化驗證碼的使用和介紹,小伙伴可以根據自己的需求進行引入;后面會繼續介紹web2.0極驗證。

 

來自：http://www.jianshu.com/p/90963f73ad5b