创建CounterSerlet, 使用getServletContext，ServletContext 从request.getSession().getServletContext();获得



@WebServlet("/CounterServlet")
public class CounterServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CounterServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            ServletContext context = request.getSession().getServletContext();
        if(null == context.getAttribute("counter")){
            context.setAttribute("counter", 1);
        }else {
            int count = (Integer)context.getAttribute("counter");
            context.setAttribute("counter", count + 1);
        }
        request.getRequestDispatcher("counter.jsp").forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}


　　

2. counter.jsp

jsp里对应的对象就是application



<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
 <%= application.getAttribute("counter") %>
</body>
</html>