1 ServletContext sc = this.getServletContext(); 2 Long personCount = (Long)sc.getAttribute("personCount"); 3 if(personCount==null){ 4 personCount=(long)0; 5 sc.setAttribute("personCount", personCount); 6 7 } 8 sc.setAttribute("personCount", (personCount+1)); 9 System.out.println("当前在线人数："+sc.getAttribute("personCount"));