配置Servlet上下文
任何servlet都可以访问Servlet上下文参数,
<web-app>
<context-param>
<param-name>contextParam</param-name>
<param-value>Hello Servlet</param-value>
</context-param>
<!--省略其他配置-->
</web-app>
servlet参数与servlet上下文参数获取方式的差别
String initParam = getInitParameter("initParam");
String contextParam = this.getServletContext().getInitParameter("contextParam");
System.out.println("Servlet初始化参数“+initParam);
System.out.println("系统初始化参数”+contextParam);