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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();
}
}
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Handle the post (using a servlet, or whatever).
The validateCaptchaForId method will return true if the response is correct.
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booleanBoolean isResponseCorrect =falseBoolean.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 } //do something according to the result! |
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