如何配置web.xml才能访问我编写的类文件啊

<?xml version="1.0" encoding="utf-8"?>

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

	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"

	version="2.5">





	<welcome-file-list>

		<welcome-file>index.jsp</welcome-file>

		<welcome-file>default.jsp</welcome-file>

	</welcome-file-list>

	<!--ip Filter

	<filter>

		<filter-name>FilterDemo24</filter-name>

		<filter-class>com.tomcat.web.FilterDemo24</filter-class>

		<init-param>

			<param-name>ip</param-name>

			<param-value>127.0.0.1</param-value>

		</init-param>

	</filter>

	<filter-mapping>

		<filter-name>FilterDemo24</filter-name>

		<url-pattern>/*</url-pattern>

	</filter-mapping>

	-->

	<!--

	<filter>

		<filter-name>FilterDemo25</filter-name>

		<filter-class>com.tomcat.web.FilterDemo25</filter-class>

		<init-param>

			<param-name>usernameGroup</param-name>

			<param-value>liu:user:admin:uper</param-value>

		</init-param>

	</filter>

	<filter-mapping>

		<filter-name>FilterDemo25</filter-name>

		<url-pattern>/*</url-pattern>

	</filter-mapping>

	-->

	<!--

	<filter>

		<filter-name>FilterDemo23</filter-name>

		<filter-class>com.tomcat.web.FilterDemo23</filter-class>

	</filter>

	<filter-mapping>

		<filter-name>FilterDemo23</filter-name>

		<url-pattern>/*</url-pattern>

	</filter-mapping>

	-->

	<!--servlet config-->

	<!--

	<servlet>

		<servlet-name>ServletGetDemo21</servlet-name>

		<servlet-class>com.tomcat.web.ServletGetDemo21</servlet-class>

	</servlet>

	<servlet-mapping>

		<servlet-name>ServletGetDemo21</servlet-name>

		<url-pattern>/ServletGetDemo21</url-pattern>

	</servlet-mapping>

	-->

	<session-config>

		<session-timeout>60</session-timeout><!--设置回话有效期为60分钟-->

	</session-config>

	<servlet>

		<servlet-name>RequestServlet1</servlet-name>

		<servlet-class>com.tomcat.web.RequestServlet1</servlet-class>

	</servlet>

	<servlet>

		<servlet-name>RequestServlet2</servlet-name>

		<servlet-class>com.tomcat.web.RequestServlet2</servlet-class>

	</servlet>

	<servlet-mapping>

		<servlet-name>RequestServlet1</servlet-name>

		<url-pattern>/RequestServlet1</url-pattern>

	</servlet-mapping>

	<servlet-mapping>

		<servlet-name>RequestServlet2</servlet-name>

		<url-pattern>/RequestServlet2</url-pattern>

	</servlet-mapping>

</web-app>