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

<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>

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"));
       }
}