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专注于Java后端开发。 不断总结，举一反三。
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Servlet 实现网页计数器

Posted on 2017-10-18 23:21  work hard work smart  阅读(729)  评论(0)  编辑  收藏  举报

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>