http://blog.csdn.net/guihaijinfen/article/details/8363839
jsp大小写敏感，url地址都大小写敏感
可以不要xmls
<web-app>
<servlet>
<servlet-mapping>
</web-app>
在javaee中建项目是可以带web.xml默认是不带的。
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<servlet>
<servlet-name>firstServlet</servlet-name>
<servlet-class>servlet.FirstServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>firstServlet</servlet-name>
<url-pattern>/servlet/firstServlet</url-pattern>
</servlet-mapping>
</web-app>