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>