java 关于分页的实现

   关于java实现分页

转自：http://www.cnblogs.com/slliang/archive/2012/08/22/2651053.html

　　1.分页工具类，封装分页信息

package com.student.util;
import java.util.List;

import com.student.entity.Person;

/**
 * 封装分页信息
 * @author Administrator
 *
 * @param <Person>
 */
public class PageModel<E> {

    //结果集
    private List<E> list;
    
    //查询记录数
    private int totalRecords;
    
    //第几页
    private int pageNo;
    
    //每页多少条记录
    private int pageSize;
    
    //总页数
    public int getTotalPages(){
        return (totalRecords + pageSize -1)/pageSize;
    }
    
    //首页
    public int getTopPage(){
        return 1;
    }
    
    //上一页
    public int getPreviousPage(){
        if(pageNo<=1){
            return 1;
        }
        return pageNo-1;
    }
    //下一页
    public int getNextPage(){
        if(pageNo>=getBottomPage()){
            return getBottomPage();
        }
        return pageNo+1;
    }
    
    //尾页
    public int getBottomPage(){
        return getTotalPages();
    }
    
    public List<E> getList() {
        return list;
    }
    public void setList(List<E> list) {
        this.list = list;
    }
    public int getTotalRecords() {
        return totalRecords;
    }
    public void setTotalRecords(int totalRecords) {
        this.totalRecords = totalRecords;
    }
    public int getPageNo() {
        return pageNo;
    }
    public void setPageNo(int pageNo) {
        this.pageNo = pageNo;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

}

　　2.测试类

public class PageModelTest{
    public static void main(String[] args){
        int pageNo=1;
        int pageSize=10;
        findUserList(pageNo,pageSize);
    }
    /**
     * 分页查询
     * @param pageNo 第几页
     * @param pageSize 每页多少条记录
     * @return PageModel<E>
     */
    public PageModel<Person> findUserList(int pageNo,int pageSize){
        PageModel<Person> pageModel = null;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        //各数据库的分页语句不一样
        
        /*oracle实现分页,三层嵌套，这里10应该为pageNo*pageSize ，0为(pageNo-1)*pageSize
        String sql="
        select column1,column2,column3,column4,column5 from    
             (select rownum rn,column1,column2,column3,column4,column5 from
                 (select column1,column2,column3,column4,column5 from table_name order by column desc)
             where rownum<=10)
         where rn>0";
        */
        //mysql实现分页
        String sql="select * from person order by id desc limit ?,? "; 
        conn=DBUtil.getUtil().getConnection();
        try {
            ps=conn.prepareStatement(sql);
            ps.setInt(1, (pageNo-1) * pageSize);
            ps.setInt(2, pageSize);
            rs=ps.executeQuery();
            List<Person> personList  = new ArrayList<Person>();
            while(rs.next()){
                Person person=new Person();
                person.setName(rs.getString("stu_name"));
                person.setPassword(rs.getString("stu_psw"));
                person.setNumber(rs.getString("stu_number"));
                person.setBirthday(rs.getDate("stu_birth"));
                person.setSex(rs.getInt("stu_sex"));
                person.setPolity(rs.getInt("stu_polity"));
                person.setBrief(rs.getString("stu_brief"));
                person.setType(rs.getInt("type"));
                person.setState(rs.getInt("state"));
                personList.add(person);
            }
            pageModel = new PageModel<Person>();
            pageModel.setList(personList);
            pageModel.setTotalRecords(getTotalRecords(conn));
            pageModel.setPageSize(pageSize);
            pageModel.setPageNo(pageNo);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                if(rs!=null){
                    rs.close();
                }
                if(ps!=null){
                    ps.close();
                }
                if(conn!=null){
                    conn.close();
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return pageModel;
    }
    /**
     * 得到总记录数，私有方法，外部无法访问，本类中使用
     * @param conn
     * @return
     */
    private int getTotalRecords(Connection conn){
        PreparedStatement ps = null;
        ResultSet rs = null;

        String sql="select count(*) from person"; 
        
        conn=DBUtil.getUtil().getConnection();
        int count=0;
        try {
            
            ps=conn.prepareStatement(sql);
            rs=ps.executeQuery();
            while(rs.next()){
                //此时根据sql语句查出的只有一列，否则不建议用int标识字段
                count = rs.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            try {
                if(rs!=null){
                    rs.close();
                }
                if(ps!=null){
                    ps.close();
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return count;
    }
}