在web.xml中配置一个servlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="WebApp_ID" version="2.5">
	<display-name>student</display-name>
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
		<welcome-file>index.htm</welcome-file>
		<welcome-file>index.jsp</welcome-file>
		<welcome-file>default.html</welcome-file>
		<welcome-file>default.htm</welcome-file>
		<welcome-file>default.jsp</welcome-file>
	</welcome-file-list>
	<servlet>
		<servlet-name>test</servlet-name>
		<servlet-class>com.test.Test</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>test</servlet-name>
		<url-pattern>/test</url-pattern>
	</servlet-mapping>
</web-app>

<servlet-name>test</servlet-name>servlet的名称
<servlet-class>com.test.Test</servlet-class>servlet的类全称（包名.类名）
<load-on-startup>1</load-on-startup>是否在服务器启动时就加载，如果不用在服务器启动时就加载可以去掉此项
<url-pattern>/test</url-pattern>servlet的访问路径