实在没办法了郁闷中。jsp调用javaBean出错,请高手看看哪出问题了
在csdn上找了个统计在线人数的javaBean,但是引用的地方就报错,搞了一个小时没搞定,高手看看是哪的问题?
/*
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()+ "\t 登入到系统\t "+(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+ "\t 退出系统\t "+(new Date()));
System.out.println( " 在线用户数为: "+getCount());
}
}
/*
调用页面onLineUser.jsp
*/
<%@page contentType= "text/html; charset=gb2312 " language= "java "
errorPage= " "%>
<%@page import= "java.util.* "%>
<html>
<jsp:useBean id= "onlineuser " scope= "application " class= "onLineUser " type= "onLineUser "> </jsp:useBean>
<head>
<title> 122 </title>
</head>
<body>
<center&g