Caused by: java.lang.IllegalArgumentException: Invalid <url-pattern> bullentin_board/captcha/captcha in servlet mapping


<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">

<servlet>

<servlet-name>Captcha-servlet</servlet-name>

<servlet-class>Captcha</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>Captcha-servlet</servlet-name>

<url-pattern>/captcha</url-pattern>

</servlet-mapping>

</web-app>