com.google.code.kaptcha.servlet.KaptchaExtend Maven / Gradle / Ivy

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A web kaptcha generation engine
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package com.google.code.kaptcha.servlet;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Date;
import java.util.Properties;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;

public class KaptchaExtend {
	private Properties props = new Properties();

	private Producer kaptchaProducer = null;

	private String sessionKeyValue = null;

	private String sessionKeyDateValue = null;

	public KaptchaExtend() {
		// Switch off disk based caching.
		ImageIO.setUseCache(false);

		this.props.put("kaptcha.border", "no");
		this.props.put("kaptcha.textproducer.font.color", "black");
		this.props.put("kaptcha.textproducer.char.space", "5");

		Config config = new Config(this.props);
		this.kaptchaProducer = config.getProducerImpl();
		this.sessionKeyValue = config.getSessionKey();
		this.sessionKeyDateValue = config.getSessionDate();
	}

	/**
	 * map it to the /url/captcha.jpg
	 * 
	 * @param req
	 * @param resp
	 * @throws ServletException
	 * @throws IOException
	 */
	public void captcha(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// Set standard HTTP/1.1 no-cache headers.
		resp.setHeader("Cache-Control", "no-store, no-cache");

		// return a jpeg
		resp.setContentType("image/jpeg");

		// create the text for the image
		String capText = this.kaptchaProducer.createText();

		// store the text in the session
		req.getSession().setAttribute(this.sessionKeyValue, capText);

		// store the date in the session so that it can be compared
		// against to make sure someone hasn't taken too long to enter
		// their kaptcha
		req.getSession().setAttribute(this.sessionKeyDateValue, new Date());

		// create the image with the text
		BufferedImage bi = this.kaptchaProducer.createImage(capText);

		ServletOutputStream out = resp.getOutputStream();

		// write the data out
		ImageIO.write(bi, "jpg", out);

		// fixes issue #69: set the attributes after we write the image in case
		// the image writing fails.

		// store the text in the session
		req.getSession().setAttribute(this.sessionKeyValue, capText);

		// store the date in the session so that it can be compared
		// against to make sure someone hasn't taken too long to enter
		// their kaptcha
		req.getSession().setAttribute(this.sessionKeyDateValue, new Date());
	}

	public String getGeneratedKey(HttpServletRequest req) {
		HttpSession session = req.getSession();
		return (String) session
				.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
	}
}