Servlet配置load-on-startup

<?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"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" metadata-complete="true" version="3.0">
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!--
Element : load-on-startup
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.
(这句话的含义是说如果设置了这个元素的值，那么在web应用程序启动的时候，会实例化这个servlet
并且调用其中的init方法)
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.
(上面的含义表示如果负数或没有当前的值设置，则某个servlet无论何时在被选择的时候才加载，包括上面的
instantiated和init)
The container may choose the order of loading of servlets with the
same load-on-start-up value.(容器可以选择一个相同的value去加载servlet)

Data Type : load-on-startupType
Enumerated Values :
-->
<servlet>
<servlet-name>HelloworldServlet</servlet-name>
<servlet-class>com.ghsy.HelloworldServlet</servlet-class>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>HelloworldServlet</servlet-name>
<url-pattern>/Helloworld</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LifecycleServlet</servlet-name>
<servlet-class>com.ghsy.LifecycleServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>LifecycleServlet</servlet-name>
<url-pattern>/lifecycle</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>InitServlet</servlet-name>
<servlet-class>com.ghsy.InitServlet</servlet-class>
<init-param>
<param-name>参数1</param-name>
<param-value>value1</param-value>
</init-param>
<init-param>
<param-name>参数2</param-name>
<param-value>value2</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>InitServlet</servlet-name>
<url-pattern>/init</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>GenericServletDemo</servlet-name>
<servlet-class>com.ghsy.GenericServletDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>GenericServletDemo</servlet-name>
<url-pattern>/generic</url-pattern>
</servlet-mapping>
</web-app>