用javabean分页显示从数据库中查找的信息报错,该怎么处理

用javabean分页显示从数据库中查找的信息报错
page_sep.jsp：

<%@ page contentType="text/html; charset=gb2312"%>
<%@ page import="java.util.Vector" %>
<%@ page import="java.lang.*" %>
<%@ page import="wu.bean.BeanArticlePage" %>
<%@ page import="wu.bean.article" %>
<jsp:useBean id="page_sep" class=wu.bean.BeanArticlePage scope="session"></jsp:useBean>
<%
int intPageSize=4; //每页显示的记录数
int currPageBegin=0; //起始记录的索引
int intPageConut=0; //总页数
int intPage=0; //待显示页码
String strPage=null; //用户请求页码
 %>

 <%
article art=new article();

Vector<article> vector=new Vector<article>();

vector=page_sep.getResultSet();

strPage=request.getParameter("pagenumber");//pagenumber

if(strPage==null){

intPage=1;

}else{

intPage=Integer.parseInt(strPage);

if(intPage<1)

intPage=1;
}
 
  //
  intPageConut=(vector.size()+intPageSize-1)/intPageSize;
 
  //调整带显示的页码
  if(intPage>intPageConut)
 
  intPage=intPageConut;
 
  //计算每一页的起始记录索引
 
  currPageBegin=intPage*intPageSize-intPageSize;

 %>
 <table align=center border=1 cellspacing=0 width=90%>
 
  <tr>
  <td align=center>作者</td>
  <td align=center>标题</td>
  <td align=center>类容</td>
  </tr>
  <%
  for(int i=currPageBegin;i<intPage*intPageSize&&i<vector.size();i++)
  {
 
  art=(article)vector.elementAt(i);
  %>
  <tr bgcolor="#f0ffff">
  <td align=center><font size=2><%=art.getUsername() %></font></td>
  <td align=center><font size=2><%=art.getTitle() %></font></td>
  <td align=center><font size=2><%=art.getContent() %></font></td>
  </tr>
  <%
  } 
  %>
 </table>
 
BeanArticlePage.java
:
package wu.bean;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Vector;

import wu.JDBC.ContantFinal;
import wu.JDBC.LoginAccess;
import wu.JDBC.SqlServerConn;

public class BeanArticlePage {

public Vector<article> getResultSet(){

LoginAccess la=new LoginAccess(new SqlServerConn());//SQLServer数据库的链接

try {

ResultSet rs=la.SetAll(new ContantFinal().artcle);//从表artcle中查找所有信息

Vector<article> vector=new Vector<article>();


while(rs.next()){

article ar=new article();

ar.setArticleID(rs.getInt("articleID"));

ar.setUsername(rs.getString("username"));

ar.setTitle(rs.getString("title"));

ar.setContent(rs.getString("content"));

vector.addElement(ar);

System.out.println("success");
}

System.out.println("success");

return vector;


} catch (SQLException e) {

e.printStackTrace();

la.Close();
}

return null;

}

}

article.java

package wu.bean;

public class article {

public int articleID=0;

public String username=null;

public String title=null;

public String content=null;