在web.xml 中加入这些数据，启动时加载，是参数，是优先级

<servlet>
        <servlet-name>initTable</servlet-name>
        <servlet-class>com.imooc.servlet.startup.InitTableServlet</servlet-class>
        <init-param>
            <param-name>database</param-name>
            <param-value>db02</param-value>
        </init-param>
        <load-on-startup>0</load-on-startup>
    </servlet>
    <servlet>
        <servlet-name>import</servlet-name>
        <servlet-class>com.imooc.servlet.startup.ImportServlet</servlet-class>
        <init-param>
            <param-name>file</param-name>
            <param-value>c:/tmp/demo.txt</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

404、500页面设置

在web.xml 中加入这些数据

	<error-page>
        <error-code>404</error-code>
        <location>/error/404.html</location>
    </error-page>
    <error-page>
        <error-code>500</error-code>
        <location>/error/500.html</location>
    </error-page>