每天学习点 验证码之Jcaptcha

如图：



代码：

ByteArrayOutputStream jpgout = new ByteArrayOutputStream();
		String id = req.getSession().getId();
		BufferedImage bimg = new DefaultManageableImageCaptchaService().getImageChallengeForID(id,req.getLocale());
		JPEGImageEncoder imgcode = JPEGCodec.createJPEGEncoder(jpgout);
		imgcode.encode(bimg);
		byte[] captchaChallengeAsJpeg = jpgout.toByteArray();
		resp.setHeader("Cache-Control", "no-store");
		resp.setHeader("Pragma", "no-cache");
		resp.setDateHeader("Expires", 0);
		resp.setContentType("image/jpeg");
		ServletOutputStream responseOutputStream = resp.getOutputStream();
		responseOutputStream.write(captchaChallengeAsJpeg);
		responseOutputStream.flush();
		responseOutputStream.close();