每个用户在访问完网站后，经常会忽略注销账户，session默认存在的时间为30分钟，因此如果需要立即关闭session而又不用麻烦用户则可以通过轮询的方法来实现。
以下通过代码的讲解：
xml配置文件
<!--轮询servlet的配置-->
<servlet>
<description></description>
<display-name>PollingServlet</display-name>
<servlet-name>PollingServlet</servlet-name>
<servlet-class>com.qf.cotroller.PollingServlet</servlet-class>
<load-on-startup>1</load-on-startup><!--设置轮询servlet在服务器启动时就加载-->
</servlet>
<servlet-mapping>
<servlet-name>PollingServlet</servlet-name>
<url-pattern>/PollingServlet</url-pattern>
</servlet-mapping>
<!--session监听器的配置-->
<listener>
<display-name>MyListener</display-name>
<listener-class>com.qf.listener.MySessionListener</listener-class>
</listener>
轮询servlet的代码实现
public class PollingServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public PollingServlet() {
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
@Override
public void init() throws ServletException {
// TODO Auto-generated method stub
System.out.println("轮询开始啦！！！");
//创建定时器对象
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
//从Context全局对象中获取存储session集合的全局变量map
Map<String , HttpSession> map = (Map<String , HttpSession>)getServletContext().getAttribute("map");
if(map!=null){//非空则执行以下操作
Set<Entry<String,HttpSession>> set = map.entrySet();
for (Entry<String, HttpSession> entry : set) {//遍历集合中每个session
long curDate = new Date().getTime();
long lastTime = entry.getValue().getLastAccessedTime();
if((curDate - lastTime)/1000 > 10){//当session没有操作的时间超过10秒则销毁
entry.getValue().invalidate();
map.remove(entry.getKey());
}
}
}
}
}, 0, 1000);//每一秒查询一次sessionmap
}
}public class MySessionListener implements HttpSessionListener {
@Override
public void sessionCreated(HttpSessionEvent evt1) {
System.out.println("session创建了!!!");
HttpSession session = evt1.getSession(); //获取session
//获取用于存储session的全局变量map
Map<String , HttpSession> map = (Map<String , HttpSession>)session.getServletContext().getAttribute("map");
if(map == null){//如果第一次存则创建一个map
map = new HashMap<String, HttpSession>();
}
map.put(session.getId(), session);//将session存入map中
session.getServletContext().setAttribute("map", map);
}
@Override
public void sessionDestroyed(HttpSessionEvent evt1) {
System.out.println("session销毁了!!!");
}
}以上为通过轮询销毁session的代码实现哦！！！！