jsp验证码制作

介绍两个功能强大的开源制作验证码组件SimpleCaptcha，JCAPTCHA。

1.配置

将下载的jar文件放置工程的lib目录下，打开工程的web.xml文件加上相应的配置

Captcha

nl.captcha.servlet.CaptchaServlet

cap.border

yes

cap.border.c

green

cap.border.th

1

cap.cap.producer

nl.captcha.obscurity.imp.DefaultCaptchaIml

cap.text.producer

org.ChineseTextProducer

cap.char.arr

2,3,4,6,7,8,9,a,b,c,d,e,f,g,h,j,k,l,m,n,o,p,q,r,s,t,u,v,x,y,z

cap.char.arr.l

4

cap.font.arr

Arial,Helvetica,Courier,TimesRoman,宋体,黑体

cap.font.size

30

cap.font.color

white

cap.obscurificator

org.FishEyeGimpyImp

cap.border

no

cap.char.arr.l

6

cap.background.c.to

white

cap.background.c.from

white

cap.distortionImp

cap.backgroundImp

cap.background.c.to

black

cap.background.c.from

black

cap.noiseImp

nl.captcha.obscurity.imp.DefaultNoiseImp

Captcha

/Captcha.jpg

以上配置可根据喜好设置。

2、调用显示

在要显示验证码的页面中加入即可显示生成的验证码

3、后台验证

验证非常简单，通过session.getAttribute(nl.captcha.servlet.Constants.SIMPLE_CAPCHA_SESSION_KEY);即可得到组件生成

的验证码，然后与前台传递的用户填写的内容比较即可。

注：如果要自定义验证码的内容可以继承DefaultTextCreator类，覆写getText()方法即可，方法返回的是一个字符串。

1、配置

下载JCAPTCHA后将jcaptcha.jar和commons-collections-2.1以上.jar(单独下载，地址：http://commons.apache.org/collections/)放置工程lib目录下。

2、Implement a CaptchaService

import com.octo.captcha.service.image.ImageCaptchaService;

import com.octo.captcha.service.image.DefaultManageableImageCaptchaService;

public class CaptchaServiceSingleton {

private static ImageCaptchaService instance = new DefaultManageableImageCaptchaService();

public static ImageCaptchaService getInstance(){

return instance;

}

}

3、编写一个产生验证码的servlet

public class ImageCaptchaServlet extends HttpServlet {

protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)

throws ServletException, IOException {

byte[] captchaChallengeAsJpeg = null;

ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();

try {

String captchaId = httpServletRequest.getSession().getId();

BufferedImage challenge =

CaptchaServiceSingleton.getInstance().getImageChallengeForID(captchaId,

httpServletRequest.getLocale());

JPEGImageEncoder jpegEncoder = JPEGCodec.createJPEGEncoder(jpegOutputStream);

jpegEncoder.encode(challenge);

} catch (IllegalArgumentException e) {

httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);

return;

} catch (CaptchaServiceException e) {

httpServletResponse.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

return;

}

captchaChallengeAsJpeg = jpegOutputStream.toByteArray();

httpServletResponse.setHeader("Cache-Control", "no-store");

httpServletResponse.setHeader("Pragma", "no-cache");

httpServletResponse.setDateHeader("Expires", 0);

httpServletResponse.setContentType("image/jpeg");

ServletOutputStream responseOutputStream =

httpServletResponse.getOutputStream();

responseOutputStream.write(captchaChallengeAsJpeg);

responseOutputStream.flush();

responseOutputStream.close();

}

}

4、将servlet添加到web.xml文件中

jcaptcha

ImageCaptchaServlet

0

jcaptcha

/jcaptcha

5、在页面中显示

6、后台验证

Boolean isResponseCorrect =Boolean.FALSE;

String captchaId = httpServletRequest.getSession().getId();

String response = httpServletRequest.getParameter("captcha_code");

try {

isResponseCorrect = CaptchaServiceSingleton.getInstance().validateResponseForID(captchaId,response);

} catch (CaptchaServiceException e) {

//TODO

}

最简单的开发过程结束，试运行一下效果！

注：要实现自己的验证引擎可以继承ListImageCaptchaEngine实现抽象方法buildInitialFactories()。