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

 1 package cn.example;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 /**
12  * 网站访问量统计小案例
13  * @author LZC
14  */
15 public class CallCount extends HttpServlet {
16 
17     public void doGet(HttpServletRequest request, HttpServletResponse response)
18             throws ServletException, IOException {
19         /*
20          *1、获取ServletContext对象
21          *2、从ServletContext对象中获取名为count的属性用来保存访问量
22          *3、如果存在，则保存回去
23          *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
24          */
25         response.setCharacterEncoding("GBK");
26         ServletContext application =this.getServletContext();
27         Integer count = (Integer) application.getAttribute("count");
28         if(count==null){
29             application.setAttribute("count", 1);
30         }else{
31             application.setAttribute("count", count+1);
32         }
33         
34          // 向浏览器输出，需要使用响应请求
35         response.setContentType("text/html");
36         PrintWriter out = response.getWriter();
37         out.println("<h2>您一共访问了 "+count+" 次</h2>");
38     }
39 }