web.xml中在Servlet中获取context-param和init-param内的参数

web.xml里面可以定义两种参数：
1.application范围内的参数，存放在servletcontext中，在web.xml中配置如下： 

 <context-param>
            <param-name>context/param</param-name>
            <param-value>avalible during application</param-value>
   </context-param>

2.servlet范围内的参数，只能在servlet的init()方法中取得，在web.xml中配置如下：

 <servlet>
     <servlet-name>MainServlet</servlet-name>
     <servlet-class>com.wes.controller.MainServlet</servlet-class>
     <init-param>
        <param-name>param1</param-name>
        <param-value>avalible in servlet init()</param-value>
     </init-param>
     <load-on-startup>0</load-on-startup>
 </servlet>

在servlet中可以通过代码分别取用： 

 package com.qisentech.controller;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 public class MainServlet extends HttpServlet {
     public MainServlet() {
         super();
       }
     public void init() throws ServletException {
           System.out.println(this.getInitParameter("param1"));
           System.out.println(getServletContext().getInitParameter("context/param"));
        }
 }

第一种参数在servlet里面可以通过getServletContext().getInitParameter("context/param")得到
第二种参数只能在servlet的init()方法中通过this.getInitParameter("param1")取