显示Servlet API主要版本，次要版本以及服务器系统信息

 package com.mhb;

 import java.io.IOException;

 import java.io.PrintWriter;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 public class ServletContextDemo extends HttpServlet {

 public void init() throws ServletException {

 }

 public void doGet(HttpServletRequest request, HttpServletResponse response)

 throws ServletException, IOException {

 //设置输出内容格式和编码

 response.setContentType("text/html;charset=gb2312");

 PrintWriter out = response.getWriter();

 //获得ServletContext实例

 ServletContext application = getServletContext();

 //主要的Servlet API版本

 int magorVersion = application.getMajorVersion();

 //次要的Servlet api版本

 int minorVersion = application.getMinorVersion();

 //服务器版本

 String info = application.getServerInfo();

 out.println("<html>");

 out.println("<body>");

 out.println("主要Servlet API版本："+magorVersion+"<br />");

 out.println("次要Servlet API版本："+minorVersion+"<br />");

 out.println("服务器版本："+info+"<br />");

 out.println("</body>");

 out.println("</html>");

 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)

 throws ServletException, IOException {

 }

 public void destroy() {

 super.destroy();

 }

 }

浏览器显示：