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);
    }
}