web.xml
配置servlet,
<servlet>
<servlet-name>first</servlet-name>
<display-name>first</display-name>
<description>The first Servlet</description>
<servlet-class>Myservlet.firstServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>first</servlet-name>
<url-pattern>/first</url-pattern>
</servlet-mapping>
<display-name>为何错误?