Why do so?
Do initialized when the server starts work [such as the] import some data into memory,
with the initialization init Servlet () method can do this.
<servlet>
<servlet-name>myser</servlet-name>
<servlet-class>com.wn.controller.MyServlet</servlet-class>
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>myser</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
1) load-on-startup element tag servlet container if this should be loaded at boot time, (instantiate and call its init () method).
2) It must be an integer value, a sequence should be loaded servlet
3) If the element does not exist or the number is negative, the container when the Servlet is requested, re-loading.
4) When the value is 0 or greater than 0, it represents the container when the application starts to load and initialize the servlet;
5) the value of a positive number, the higher the priority of the servlet, the more loaded first when the application starts.
6) When the values are the same, the container loading order of their choice.
