在servlet的配置当中，<load-on-startup>5</load-on-startup>的含义是：
标记容器是否在启动的时候就加载这个servlet。
当值为0或者大于0时，表示容器在应用启动时就加载这个servlet；
当是一个负数时或者没有指定时，则指示容器在该servlet被选择时才加载。
正数的值越小，启动该servlet的优先级越高。
Servlet specification:
The load-on-startup element
indicates that this servlet should be loaded
(instantiated and have its init() called) on the
startup of the web application. The optional contents
of these element must be an integer indicating the
order in which the servlet should be loaded. If the
value is a negative integer, or the element is not
present, the container is free to load the servlet
whenever it chooses. If the value is a positive
integer or 0, the container must load and initialize
the servlet as the application is deployed. The
container must guarantee that servlets marked with lower
integers are loaded before servlets marked with higher
integers. The container may choose the order of
loading of servlets with the same load-on-start-up value.
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/enjoyo/archive/2007/08/27/1761033.aspx
EG：
<servlet>
<servlet-name>LogIniter</servlet-name>
<servlet-class>com.init.LogIniter</servlet-class>
<init-param>
<param-name>log4j</param-name>
<param-value>/WEB-INF/log4j.properties</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet>
<servlet-name>DicDataIniter</servlet-name>
<servlet-class>com.init.DicDataIniter</servlet-class>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>LogIniter</servlet-name>
<url-pattern>/LogIniter</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>DicDataIniter</servlet-name>
<url-pattern>/DicDataIniter</url-pattern>
</servlet-mapping>