/**这是管理user信息的类

文件名为onLineUser.java

*/
import javax.servlet.http.*;
import javax.servlet.*;
import java.util.*;
public class onLineUser implements HttpSessionBindingListener {
public onLineUser(){
}
private Vector users=new Vector();
public int getCount(){
users.trimToSize();
return users.capacity();
}
public boolean existUser(String userName){
users.trimToSize();
boolean existUser=false;
for (int i=0;i<users.capacity();i++ )
{
if (userName.equals((String)users.get(i)))
{
existUser=true;
break;
}
}
return existUser;
}
public boolean deleteUser(String userName) {
users.trimToSize();
if(existUser(userName)){
int currUserIndex=-1;
for(int i=0;i<users.capacity();i++){
if(userName.equals((String)users.get(i))){
currUserIndex=i;
break;
}
}
if (currUserIndex!=-1){
users.remove(currUserIndex);
users.trimToSize();
return true;
}
}
return false;
}
public Vector getOnLineUser()
{
return users;
}
public void valueBound(HttpSessionBindingEvent e) {
users.trimToSize();
if(!existUser(e.getName())){
users.add(e.getName());
System.out.print(e.getName()+" 登入到系统 "+(new Date()));
System.out.println(" 在线用户数为："+getCount());
}else
System.out.println(e.getName()+"已经存在");
}
public void valueUnbound(HttpSessionBindingEvent e) {
users.trimToSize();
String userName=e.getName();
deleteUser(userName);
System.out.print(userName+" 退出系统 "+(new Date()));
System.out.println(" 在线用户数为："+getCount());
}
}