Servlet----------用servlet写一个“网站访问量统计“的小案例

 package cn.example;

 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;

 /**

  * 网站访问量统计小案例

  * @author LZC

  */

 public class CallCount extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         /*

          *1、获取ServletContext对象

          *2、从ServletContext对象中获取名为count的属性用来保存访问量

          *3、如果存在，则保存回去

          *4、如果不存在，说明是第一次访问，向ServletContext中保存名为count的属性，值 为1

          */

         response.setCharacterEncoding("GBK");

         ServletContext application =this.getServletContext();

         Integer count = (Integer) application.getAttribute("count");

         if(count==null){

             application.setAttribute("count", 1);

         }else{

             application.setAttribute("count", count+1);

         }

          // 向浏览器输出，需要使用响应请求

         response.setContentType("text/html");

         PrintWriter out = response.getWriter();

         out.println("<h2>您一共访问了 "+count+" 次</h2>");

     }

 }