安装
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 }
本文来自博客，转载请标明出处：http://blog.csdn.net/alexjjf/archive/2006/10/31/1359333.aspx
