1 package boom.servlet;
 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  * 案例 ：统计访问量
13  * @author Administrator
14  *
15  */
16 public class AServlet extends HttpServlet {
17 
18     public void doGet(HttpServletRequest request, HttpServletResponse response)
19             throws ServletException, IOException {
20         /**
21          * 1.获取ServletContext对象
22          * 2.从ServletContext对象中获取count属性
23          * 3.如果存在：访问量+1，在保存；
24          * 4.如果不存在，就说明是第一次访问，就向ServletContext中报存count，值为1
25          */
26         ServletContext app =this.getServletContext();
27         Integer count = (Integer) app.getAttribute("count");
28         if(count == null){
29             app.setAttribute("count", 1);
30         }else{
31             app.setAttribute("count", count+1);
32         }
33         /**
34          * 向浏览器输出：需要使用响应对象
35          */
36         PrintWriter pw = response.getWriter();
37         pw.print("<h1>" + count + "<h1>");
38     }
39 
40 }