JSP实现的AJAX聊天室

package servlet; import java.util.*; import java.util.concurrent.ConcurrentLinkedQueue; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import javax.servlet.http.HttpServlet; import entity.Message; /** * 服务器启动时执行的Servlet * @author Admin * */ public class Global extends HttpServlet implements ServletContextListener { private static final long serialVersionUID = -8680344467984908901L; private Timer clearTimer =null; //清空聊天记录用Timer /** * 服务器停止时执行该事件 */ public void contextDestroyed(ServletContextEvent sce) { clearTimer.cancel(); } /** * 服务器启动时进行初始化 */ public void contextInitialized(ServletContextEvent sce) { //获取XML配置文件中是否使用线程安全的容器保存消息记录 boolean isSynch = sce.getServletContext().getInitParameter("isSynch").equals("1")?true:false; //获取是否线程同步的设置 //在Application中创建出消息集合 Map<String, ConcurrentLinkedQueue<Message>> msglist = null; if(isSynch){ msglist = new Hashtable<String, ConcurrentLinkedQueue<Message>>(); }else { msglist = new HashMap<String, ConcurrentLinkedQueue<Message>>(); } sce.getServletContext().setAttribute("totalmsglist", msglist); //在Application中创建出在线用户集合 List<String> userlist = null; if(isSynch){ userlist = new Vector<String>(); }else { userlist = new ArrayList<String>(); } sce.getServletContext().setAttribute("userlist", userlist); //获取XML配置文件中每隔多久清空一次聊天记录(毫秒为单位),并启动自动清除器 int task = Integer.parseInt(sce.getServletContext().getInitParameter("clearUserInterval")); if(task > 0){ clearTimer = new Timer(); clearTimer.schedule(ClearMessageTask.getInstance(msglist), new Date(), task); } } /** * 消息记录自动清除器 * @author Admin * */ static class ClearMessageTask extends TimerTask{ private ClearMessageTask(Map<String, ConcurrentLinkedQueue<Message>> msgList){ this.msgList = msgList; } private Map<String, ConcurrentLinkedQueue<Message>> msgList; private static ClearMessageTask clear = null; public static TimerTask getInstance(Map<String, ConcurrentLinkedQueue<Message>> msgList){ if(clear == null){ clear = new ClearMessageTask(msgList); } return clear; } @Override public void run() { System.out.print("正在清空服务器的消息记录:当前记录["+msgList.size()+"条]"); //msgList.clear(); System.out.println("清空完毕,还剩下["+msgList.size()+"]条"); } } }