Global.java文件：

1 import javax.servlet.ServletContext; 2 import javax.servlet.ServletContextEvent; 3 import javax.servlet.ServletContextListener; 4 import javax.servlet.ServletRequest; 5 import javax.servlet.ServletRequestEvent; 6 import javax.servlet.ServletRequestListener; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpSession; 9 import javax.servlet.http.HttpSessionEvent;10 import javax.servlet.http.HttpSessionListener;11 12 public class Global implements ServletContextListener, HttpSessionListener,13         ServletRequestListener {14 15     @Override16     public void contextInitialized(ServletContextEvent sce) {17         // TODO Auto-generated method stub18         System.out.println("网站启动");19         ServletContext application = sce.getServletContext();20         application.setAttribute("count", 10);21     }22 23     @Override24     public void contextDestroyed(ServletContextEvent sce) {25         // TODO Auto-generated method stub26         ServletContext application = sce.getServletContext();27         application.setAttribute("count", 0);28         System.out.println("网站停止");29     }30 31     @Override32     public void requestInitialized(ServletRequestEvent arg0) {33         // TODO Auto-generated method stub34         System.out.println("服务器接收一个请求");35         ServletRequest request = arg0.getServletRequest();36         if (request instanceof HttpServletRequest) {37             HttpServletRequest httpRequest = (HttpServletRequest) request;38             String url = httpRequest.getRequestURI();39             System.out.println(url);40         }41     }42 43     @Override44     public void requestDestroyed(ServletRequestEvent arg0) {45         // TODO Auto-generated method stub46         System.out.println("服务器销毁一个请求");47     }48 49     @Override50     public void sessionCreated(HttpSessionEvent arg0) {51         // TODO Auto-generated method stub52         System.out.println("服务器创建一个会话");53         HttpSession session = arg0.getSession();54         session.setAttribute("count", 10);55 56         ServletContext application = session.getServletContext();57         Object obj = application.getAttribute("count");58         if (obj instanceof Integer) {59             Integer appCount = (Integer) obj;60             appCount += 1;61             application.setAttribute("count", appCount);62         }63     }64 65     @Override66     public void sessionDestroyed(HttpSessionEvent arg0) {67         // TODO Auto-generated method stub68         System.out.println("服务器销毁一个会话");69         HttpSession session = arg0.getSession();70         ServletContext application = session.getServletContext();71         Object obj = application.getAttribute("count");72         if (obj instanceof Integer) {73             Integer appCount = (Integer) obj;74             appCount -= 1;75             application.setAttribute("count", appCount);76         }77     }78 }

web.xml文件：

1 
      2 
      
       4  
       
        5   
        
         Global
        6  
       7