**
* 生成验证码
*
* @param request
* @param response
* @throws Exception
*/
@RequestMapping(value = "captcha.htm", method = RequestMethod.GET)
public void captcha(HttpServletRequest request, HttpServletResponse response)
throws Exception {
response.setDateHeader("Expires", 0);
response.setHeader("Cache-Control",
"no-store, no-cache, must-revalidate");
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
response.setHeader("Pragma", "no-cache");
response.setContentType("image/jpeg");
String capText = captchaProducer.createText();
request.getSession().setAttribute(
com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY, capText);
BufferedImage bi = captchaProducer.createImage(capText);
ServletOutputStream out = response.getOutputStream();
ImageIO.write(bi, "jpg", out);
try {
out.flush();
} finally {
out.close();
}
}