javabean+jsp的分页

我用javabean+jsp写了个分页技术，哪里都正常，就是点下一页。上一页没反应，始终都显示第一页，详细代码如下。Java code:
package com.cn.bean;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import com.cn.db.Jdbc;

public class Fenye {
private int maxpage;// 最大页码数
private int maxsum;// 记录总数
private int rowpage = 3;// 每页显示的记录数
private ResultSet result;// 每页的数据集
private int nowpage = 1;// 当前页码
private String tablename;// 表名称
private String typename;// 字段名

public Fenye(String tablename,String typename){
setTablename(tablename);
setMaxsum(tablename);
setTypename(typename);
setMaxpage();
}
public ResultSet getResult(int nowpage){
this.nowpage=nowpage;
Jdbc jd=new Jdbc();
Statement st;
try {
st = jd.getCon().createStatement();
result=st.executeQuery("select top "+getRowpage()+" * from (select *,row_number() over (order by "+getTypename()+" ) as rowno from "+getTablename()+" ) as a where rowno>"+(nowpage-1)*getRowpage());
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
public int getMaxpage() {