pagedao.java

通过jsp,servlet,javaBean,三成架构实现的好友通讯录系统

package com.Dao;
import java.sql.*;
public class pageDao
{
    private String driver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
    private String url="jdbc:microsoft:sqlserver://127.0.0.1:1433;databaseName=addressBook";
    private String dbuser="sa";
    private String dbpass="sa";
    public pageDao() {}
    //获得数据库的连接
    public Connection getConnection()
    {
        Connection conn=null;
        try
        {
            Class.forName(driver);
            conn=DriverManager.getConnection(url,dbuser,dbpass);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return conn;
    }
    //关闭数据库的连接
    public void closeConnection(Connection conn)
    {
        if(conn!=null)
        {
            try
            {
                conn.close();
            }
            catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }
    //返回查询的结果集的方法
    public ResultSet getResults()
    {
        Connection conn=null;
        conn=this.getConnection();
        Statement sm=null;
        ResultSet rs=null;
        String sql="select * from BOOK";
        //注意：返回的结果集应该是可滚动的！！
        try
        {
            sm=conn.createStatement
               (ResultSet.TYPE_SCROLL_INSENSITIVE,
                ResultSet.CONCUR_READ_ONLY);
            //sm=conn.createStatement();
            rs=sm.executeQuery(sql);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return rs;
    }
    //获得记录的总条数
    public int getRows()
    {
        Connection conn=this.getConnection();
        int rows=0;
        try
        {
            Statement sm=conn.createStatement();
            String sql="select count(*) as row from BOOK";
            ResultSet rs=sm.executeQuery(sql);
            rs.next();
            rows=rs.getInt("row");
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return rows;
    }
    //获得总页数
    public int getPages(int pageSize)//根据每页有几条记录，求出总页数
    {
        int totPage=1;//总页数
        int temp=0;
        int rows=this.getRows();//总共有多少条记录--72/5=14.4
        temp=rows%pageSize;//看有没有余数
        if(temp==0)
        {
            totPage=rows/pageSize;
        }
        else
        {
            totPage=(int)(Math.floor(rows/pageSize)+1);
        }
        if(totPage==0)
        {
            totPage=1;
        }
        return totPage;
    }
}