Servlet域对象ServletContext小应用------计算网站访问量

 package cn.yzu;
 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 AServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         ServletContext application=this.getServletContext();
         Integer count=(Integer) application.getAttribute("count");
         if(count==null)
         {
             count=1;
             application.setAttribute("count",count);
         }
         else
             application.setAttribute("count",++count);
         PrintWriter writer=response.getWriter();
         writer.print("<h1>"+count+"</h1>");
     }
     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         doGet(request, response);
     }
 }