nulla..non ottengo nulla.. per mappata tu intendi il file web.xml? è creato bene..se vuoi lo posto..
codice:
<?xml version="1.0" encoding="ISO-8859-1"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">

  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>



    <servlet>
        <servlet-name>valid</servlet-name>
        <servlet-class>ValidateServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>valid</servlet-name>
        <url-pattern>/validate</url-pattern>
    </servlet-mapping>



</web-app>