tomcat上启动spring报错-位置不正确

tomcat下启动spring报错---位置不正确

<servlet>      <servlet-name>demo</servlet-name>      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    </servlet><servlet-mapping>    <servlet-name>demo</servlet-name><url-pattern>/demoServlet</url-pattern></servlet-mapping>