监听器在线用户列表

index.jsp

在线用户列表:<br>
<%
List<User> userList = (List<User>)application.getAttribute("userList");
if(userList!=null) {
    for(User u : userList) {
        out.print(u+"<br>");
    }
}
%>

User.java

import java.text.SimpleDateFormat;
import java.util.Date;

public class User {
    private String sessionid;
    private Date firstTime;

    public String getSessionid() {
        return sessionid;
    }

    public void setSessionid(String sessionid) {
        this.sessionid = sessionid;
    }

    public Date getFirstTime() {
        return firstTime;
    }

    public void setFirstTime(Date firstTime) {
        this.firstTime = firstTime;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((firstTime == null) ? 0 : firstTime.hashCode());
        result = prime * result + ((sessionid == null) ? 0 : sessionid.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        User other = (User) obj;
        if (firstTime == null) {
            if (other.firstTime != null)
                return false;
        } else if (!firstTime.equals(other.firstTime))
            return false;
        if (sessionid == null) {
            if (other.sessionid != null)
                return false;
        } else if (!sessionid.equals(other.sessionid))
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "User [sessionid=" + sessionid + ", 最近登录时间="
                + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(firstTime) + "]";
    }

}

TestSessionlistener.java

public void sessionCreated(HttpSessionEvent sessionEvent) {
        userCount++;
        if(userList==null) {
            userList = new ArrayList<User>();
        }
        HttpSession session = sessionEvent.getSession();
        
        String sessionid = session.getId();
        long stime = session.getCreationTime();
        
        if(!checkUsersSession(sessionid, userList)) {
            User u = new User();
            u.setFirstTime(new Date(stime));
            u.setSessionid(sessionid);
            userList.add(u);
        }
        
        session.getServletContext().setAttribute("userCount", userCount);
        session.getServletContext().setAttribute("userList", userList);
    }

    private boolean checkUsersSession(String sessionid, ArrayList<User> userList2) {
        for(User u : userList2) {
            if(u.getSessionid().equals(sessionid)) {
                return true;
            }
        }
        return false;
    }

    /**
     * @see HttpSessionListener#sessionDestroyed(HttpSessionEvent)
     */
    public void sessionDestroyed(HttpSessionEvent sessionEvent) {
        userCount--;    
        HttpSession session = sessionEvent.getSession();    

        String sessionid = session.getId();
        System.out.println(sessionid + "的用户下线");
        
        if(checkUsersSession(sessionid, userList)) {
//            for(User u : userList) {
//                if(sessionid.equals(u.getSessionid())) {
//                    userList.remove(u);
//                }
//            }
            Iterator<User> iter = userList.iterator();
            while(iter.hasNext()) {
                User u = iter.next();
                if(u.getSessionid().equals(sessionid)) {
                    iter.remove();
                }
            }
        }
        session.getServletContext().setAttribute("userCount", userCount);
        session.getServletContext().setAttribute("userList", userList);
    }

}