import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
private void getCaptchaImage(HttpServletRequest request, HttpServletResponse response) throws IOException
{
	String seed = request.getParameter("seed");
	if (seed == null || seed.isEmpty())
	{
		response.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE);
		return;
	}
	int seed_;
	try
	{
		seed_ = Integer.parseInt(seed);
	}
	catch (NumberFormatException i)
	{
		response.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE);
		return;
	}
	PredictableCaptchaTextProducer producer = new PredictableCaptchaTextProducer(seed_);
	final Captcha captcha = new Captcha.Builder(160, 50).addText(producer).addBackground(new GradiatedBackgroundProducer()).addNoise().gimp(new FishEyeGimpyRenderer()).addBorder().build();
	CaptchaServletUtil.writeImage(response, captcha.getImage());
}
 

import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
@Override
public void doGet(final HttpServletRequest req, final HttpServletResponse resp)
    throws ServletException,
    IOException {
    final HttpSession session = req.getSession();

    final Captcha captcha = new Captcha.Builder(_width, _height)
        .addText()
        .addBackground(new GradiatedBackgroundProducer())
        .gimp()
        .addBackground(new FlatColorBackgroundProducer(new Color(238, 238, 238)))
        .addBorder()
        .addNoise()
        .build();

    session.setAttribute(NAME, captcha);

    CaptchaServletUtil.writeImage(resp, captcha.getImage());
}
 

import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
@At("/captcha/update")
	@Ok("raw:image/png")
	public BufferedImage updateCaptcha(HttpSession session, @Param("w") int w, @Param("h") int h) {
		if (w * h == 0) { //长或宽为0?重置为默认长宽.
			w = 200;
			h = 60;
		}
		Captcha captcha = new Captcha.Builder(w, h)
								.addText().addBackground(new GradiatedBackgroundProducer())
//								.addNoise(new StraightLineNoiseProducer()).addBorder()
								.gimp(new FishEyeGimpyRenderer())
								.build();
		String text = captcha.getAnswer();
		session.setAttribute(Toolkit.captcha_attr, text);
		return captcha.getImage();
	}
 

import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
    //ColoredEdgesWordRenderer wordRenderer = new ColoredEdgesWordRenderer(COLORS, FONTS);
    ColoredEdgesWordRenderer wordRenderer = new ColoredEdgesWordRenderer(COLORS, FONTS, 1f);
    Captcha captcha = new Captcha.Builder(_width, _height).addText(wordRenderer)
            //.gimp()
            .addNoise()
            //.addBackground(new GradiatedBackgroundProducer())
            //.addBackground(new TransparentBackgroundProducer())
            //.addBackground(new FlatColorBackgroundProducer(Color.lightGray))
            .addBackground(new GradiatedBackgroundProducer(Color.lightGray, Color.white))
            .build();

    CaptchaServletUtil.writeImage(resp, captcha.getImage());
    req.getSession().setAttribute(NAME, captcha);
}
 

import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
    ColoredEdgesWordRenderer wordRenderer = new ColoredEdgesWordRenderer(COLORS, FONTS);
    Captcha captcha = new Captcha.Builder(_width, _height).addText(wordRenderer)
            .gimp()
            .addNoise()
            .addBackground(new GradiatedBackgroundProducer())
            .build();

    CaptchaServletUtil.writeImage(resp, captcha.getImage());
    req.getSession().setAttribute(NAME, captcha);
}
 

import nl.captcha.backgrounds.GradiatedBackgroundProducer; //导入依赖的package包/类
/**
 * Creates a {@link Captcha} and stores it in the session.
 *
 * @param width  the width of the image
 * @param height the height of the image
 * @return {@link BufferedImage} containing the captcha image
 */
public BufferedImage createCaptcha(int width, int height)
{
	Captcha captcha = new Captcha.Builder(width, height).addText()
														.addBackground(new GradiatedBackgroundProducer())
														.gimp()
														.addNoise()
														.addBorder()
														.build();
	session.setAttribute(Captcha.NAME, captcha);
	return captcha.getImage();
}