spring kaptcha 验证码

<bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
		<property name="config">
			<bean class="com.google.code.kaptcha.util.Config">
				<constructor-arg>
					<props>
						<prop key="kaptcha.border">no</prop>
						<prop key="kaptcha.border.color">105,179,90</prop>
						<prop key="kaptcha.textproducer.font.color">red</prop>
						<prop key="kaptcha.image.width">250</prop>
						<prop key="kaptcha.textproducer.font.size">90</prop>
						<prop key="kaptcha.image.height">90</prop>
						<prop key="kaptcha.session.key">code</prop>
						<prop key="kaptcha.textproducer.char.length">4</prop>
						<prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>
					</props>
				</constructor-arg>
			</bean>
		</property>
	</bean>

@RequestMapping("/captcha-image")
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        response.setDateHeader("Expires", 0);
        // Set standard HTTP/1.1 no-cache headers.
        response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
        // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
        response.addHeader("Cache-Control", "post-check=0, pre-check=0");
        // Set standard HTTP/1.0 no-cache header.
        response.setHeader("Pragma", "no-cache");
        // return a jpeg
        response.setContentType("image/jpeg");
        // create the text for the image
        String capText = captchaProducer.createText();
        // store the text in the session
        request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);
        // create the image with the text
        BufferedImage bi = captchaProducer.createImage(capText);
        ServletOutputStream out = response.getOutputStream();
        // write the data out
        ImageIO.write(bi, "jpg", out);
        try {
            out.flush();
        } finally {
            out.close();
        }
        return null;
    }

<input name="kaptcha" type="text" id="kaptcha" maxlength="4" class="chknumber_input" /> 
</label>
<img src="/ClinicCountManager/captcha-image.do" width="55" height="20" id="kaptchaImage" style="margin-bottom: -3px"/> 
<script type="text/javascript"> 
$(function(){ 
$('#kaptchaImage').click(function () {//生成验证码
$(this).hide().attr('src', '/ClinicCountManager/captcha-image.do?' + Math.floor(Math.random()*100) ).fadeIn(); }) 
}); 

</script> 

String code = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);