官方網(wǎng)址：http://code.google.com/p/kaptcha 

默認(rèn)配置即可滿足大部分用途。 
<servlet> 
<servlet-name>Kaptcha</servlet-name> 
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class> 
</servlet> 
<servlet-mapping> 
<servlet-name>Kaptcha</servlet-name> 
<url-pattern>/kaptcha</url-pattern> 
</servlet-mapping> 

<form action="submit.action"> 
<img src="/kaptcha" /> 
<input type="text" name="kaptcha" value="" /> 
</form> 


String kaptchaExpected = (String)request.getSession() .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY); 
String kaptchaReceived = request.getParamater("kaptcha"); 
if (kaptchaReceived == null || !kaptchaReceived.equalsIgnoreCase(kaptchaExpected)){ setError("kaptcha", "Invalid validation code.");} 



可以通過實(shí)現(xiàn)一些里面的類。擴(kuò)展自己的需要。 

實(shí)現(xiàn)TextProducer類可以設(shè)置自己想要的隨機(jī)數(shù)。 
<init-param> 
<param-name>kaptcha.textproducer.impl</param-name> 
<param-value>springdemo.util.TextDemo</param-value> 
</init-param> 
<init-param> 
<param-name>kaptcha.textproducer.font.names</param-name> 
<param-value>新宋體</param-value> 
</init-param> 

詳細(xì)參數(shù)列表參見：http://code.google.com/p/kaptcha/wiki/ConfigParameters