验证码

<script>function StorePage(){d=document;t=d.selection?(d.selection.type!='None'?d.selection.createRange().text:''):(d.getSelection?d.getSelection():'');void(keyit=window.open('http://www.365key.com/storeit.aspx?t='+escape(d.title)+'&u='+escape(d.location.href)+'&c='+escape(t),'keyit','scrollbars=no,width=475,height=575,left=75,top=20,status=no,resizable=yes'));keyit.focus();}</script>

Add jcaptcha-all.jar (provided in bin-distribution) and ehcache.jar (not provided see ehcache site) to your application class path, ie in you WEB-INF/lib folder.

实例一个jcaptcha服务，注意，必须是单例模式的

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;
}
}

注:以上是默认的一个实现，下面是其他更多的实现

• SimpleListSoundCaptchaEngine //还可以用声音，真爽哦
• SpellerSoundCaptchaEngine
• SpellerSoundCaptchaEngine
• DefaultGimpyEngineCaptcha
• BaffleListGimpyEngineCaptcha
• BasicListGimpyEngineCaptcha
• DeformedBaffleListGimpyEngineCaptcha
• DoubleRandomListGimpyEngineCaptcha
• SimpleListImageCaptchaEngineCaptcha
• SimpleFishEyeEngineCaptcha

具体请参考官方说明

编写一个产生图片的servlet

import com.octo.captcha.service.CaptchaServiceException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;


public class ImageCaptchaServlet extends HttpServlet {


public void init(ServletConfig servletConfig) throws ServletException {

super.init(servletConfig);

}


protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {

byte[] captchaChallengeAsJpeg = null;
// the output stream to render the captcha image as jpeg into
ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();
try {
// get the session id that will identify the generated captcha.
//the same id must be used to validate the response, the session id is a good candidate!
String captchaId = httpServletRequest.getSession().getId();
// call the ImageCaptchaService getChallenge method
BufferedImage challenge =
CaptchaServiceSingleton.getInstance().getImageChallengeForID(captchaId,
httpServletRequest.getLocale());

// a jpeg encoder
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();

// flush it in the response
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();
}
}

为servlet修改web.xml配置文件

<servlet>
<servlet-name>jcaptcha</servlet-name>
<servlet-class>ImageCaptchaServlet</servlet-class>
<load-on-startup>0</load-on-startup>
</servlet>


<servlet-mapping>
<servlet-name>jcaptcha</servlet-name>
<url-pattern>/jcaptcha</url-pattern>
</servlet-mapping>

编写你的客户端的展示

<img src="jcaptcha">
<input type='text' name='j_captcha_response' value=''>

上面的src="jcaptcha" 就是调用了上面的servlet,text里是用户填写的确认验证码

后台逻辑验证

Boolean isResponseCorrect =Boolean.FALSE;
//remenber that we need an id to validate!
String captchaId = httpServletRequest.getSession().getId();
//retrieve the response
String response = httpServletRequest.getParameter("j_captcha_response");
// Call the Service method
try {
isResponseCorrect = CaptchaServiceSingleton.getInstance().validateResponseForID(captchaId,
response);
} catch (CaptchaServiceException e) {
//should not happen, may be thrown if the id is not valid
}