JAVA MYSQL做分页

看main 

package com.hcwy.test.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.hcwy.basic.jdbc.DBConnection;
import com.hcwy.basic.page.PageBean;

public class ArticlesDAO {

    private static final Map HashMap = null;

    private PreparedStatement pstmt;

    private ResultSet rs;

    private Connection con;

//  private DBConnection conn;


    public Connection conn(){
        try {
            Class.forName("com.mysql.jdbc.Driver");
            try {
                con=DriverManager.getConnection("jdbc:mysql://localhost:3316/hcwy","root","root");
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return con;
    }


    //查询SQL
    public ArrayList chaSQL(String sql){
        ArrayList list=new ArrayList();
        try {

            pstmt=this.conn().prepareStatement(sql);
            rs=pstmt.executeQuery();
            ResultSetMetaData rsmd=rs.getMetaData();
            int count=rsmd.getColumnCount();
            while(rs.next()){
//              System.out.println("名字是-->"+rsmd.getColumnName(i)+"	 得到的object是-->"+rs.getObject(i)+"   "+i);
                HashMap map=new HashMap();
                for(int i=0;i<count;i++){
                    map.put(rsmd.getColumnName(i+1), rs.getObject(i+1));
                }
                list.add(map);

            }


        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;

}

    //查询所总条数
    public int count(String name){
        String sql="select count(*) as aa from "+name;
        int i=0;
        try {
            pstmt=this.conn().prepareStatement(sql);
            rs=pstmt.executeQuery();
            if(rs.next()){
                i=rs.getInt("aa");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return i;
    }



    //查询SQL带分页
    public ArrayList chaSQL(String sql,String name,PageBean page){
        ArrayList list=new ArrayList();
        if(page!=null){
            page.setTotalCount(this.count(name));
            sql=sql+" limit "+page.getStart()+","+page.getPageSize();

        }
        System.out.println(sql);
        try {

            pstmt=this.conn().prepareStatement(sql);
            rs=pstmt.executeQuery();
            ResultSetMetaData rsmd=rs.getMetaData();

            int count=rsmd.getColumnCount();//得到表里字段的总数
            while(rs.next()){
//              System.out.println("名字是-->"+rsmd.getColumnName(i)+"	 得到的object是-->"+rs.getObject(i)+"   "+i);
                HashMap map=new HashMap();
                for(int i=0;i<count;i++){
                    map.put(rsmd.getColumnName(i+1), rs.getObject(i+1));//名字和值
                }
                list.add(map);

            }


        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;

}





    public static void main(String[] args) {

         PageBean page=new PageBean();
        ArticlesDAO dd=new ArticlesDAO();
        ArrayList list=dd.chaSQL("select * from articles","articles",page);//如果这里不写page和articles的意思 就是说不要分页
        //任何对象都能解析
        for(int i=0;i<list.size();i++){
            HashMap map=(HashMap)list.get(i);

            Iterator it=map.keySet().iterator();
            while(it.hasNext()){
                Object id=it.next();
                System.out.println(""+map.get(id));

            }

                System.out.println("
");

        }


//      ArticlesDAO dd=new ArticlesDAO();
//      System.out.println(dd.count("articles"));



    }


}

在看PAGEBEAN 

package com.hcwy.basic.page;

public class PageBean {

    private static final int DEFAULT_PAGE_SIZE = 20;

    private int pageSize = DEFAULT_PAGE_SIZE;  // 每页的记录数

    private int start=0;  // 当前页第一条数据在List中的位置,从0开始

    private int page=1;  //当前页

    private int totalPage=0;  //总计有多少页

    private int totalCount=0;  // 总记录数
////////////////
//  构造函数
    public PageBean() {
    }

    public PageBean(int page) {
        this.page=page;
    }

/////////////////

    public void setPage(int page) {
        if(page>0) {
            start=(page-1)*pageSize;
            this.page = page;
        }
    }

    public int getPage() {
        return page;
    }

    public int getPageSize() {
        return pageSize;
    }

    public PageBean setPageSize(int pageSize) {
        this.pageSize = pageSize;
        return this;
    }
    /**
     * @return the start
     */
    public int getStart() {
        return start;
    }

    //  此位置根据计算得到
    protected void setStart() {
    }

/**
     * @return the totalCount
     */
    public int getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(int totalCount) {
        this.totalCount=totalCount;
        totalPage = (int) Math.ceil((totalCount + pageSize - 1) / pageSize);
        start=(page-1)*pageSize;
    }

    //  总页面数根据总数计算得到
    protected void setTotalPage() {

    }

    public int getTotalPage() {
        return totalPage;
    }


///////////////
    //获取上一页页数
    public int getLastPage() {
        if(hasLastPage()) {
            return page-1;
        }
        return page;
    }
    public int getNextPage() {
        if(hasNextPage()) {
            return page+1;
        }
        return page;
    }
    /**
     * 该页是否有下一页.
     */
    public boolean hasNextPage() {
        return page < totalPage;
    }

    /**
     * 该页是否有上一页.
     */
    public boolean hasLastPage() {
        return page > 1;
    }


}