boarddao.java

java写的一个简单的bbs系统

package com.ibm.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.ibm.common.DBConnection;
import com.ibm.vo.BoardVO;

public class BoardDAO {
  private static BoardDAO bdao=null;
private PreparedStatement ps;
private ResultSet rs;
  
  public BoardDAO()
  {
	  
  }
  
  public static BoardDAO getInstance()
  {
	  if(bdao==null)
	  {
		  bdao=new BoardDAO();
		  return bdao;
	  }else
	  {
		  return bdao;
	  }
  }
  
  /**
   * 根据子版块的id返回该版块的所有信息
   * @param con
   * @param boardid
   * @return
   */
  public BoardVO queryByBoardid(Connection con,int boardid)
  {
	  BoardVO bvo=new BoardVO();
	  String sql="select * from board where boardid =?";
	try {
		ps=con.prepareStatement(sql);
		ps.setInt(1, boardid);
		rs=ps.executeQuery();
		while(rs.next())
		{
			bvo.setBoardid(rs.getInt("boardid"));
			bvo.setBoardname(rs.getString("boardname"));
			bvo.setParentid(rs.getInt("parentid"));
		}
	} catch (SQLException e) {
	
		e.printStackTrace();
	}
	
	return bvo;
  }
  
  /**
   * 返回子板块列表
   * @param con
   * @return
   */
  public List queryAllBoard(Connection con)
  {
	List list=new ArrayList();
//	BoardVO bvo=null;
	String sql="select * from board";
	try {
		ps=con.prepareStatement(sql);
		rs=ps.executeQuery();
		while(rs.next())
		{
			BoardVO bvo=new BoardVO();
//			bvo=BoardVO.getInstance();
			bvo.setBoardid(rs.getInt("boardid"));
			bvo.setBoardname(rs.getString("boardname"));
			bvo.setParentid(rs.getInt("parentid"));
			
			list.add(bvo);
		}
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
//	finally{
//		DBConnection.getInstance().close(null, ps, null, rs, con);
//	}
	return list;
  }
  /**
   * 根据主版块的id查询子版块列表
   * @param con
   * @param parentid
   * @return
   */
  public List queryByParentid(Connection con,int parentid)
  {
	  List list=new ArrayList();
	  String sql="select * from board where parentid=?";
	  try {
		ps=con.prepareStatement(sql);
		ps.setInt(1, parentid);
		rs=ps.executeQuery();
		while(rs.next())
		{
			BoardVO bvo=new BoardVO();
            bvo.setBoardid(rs.getInt("boardid")); 
			bvo.setBoardname(rs.getString("boardname"));
			bvo.setParentid(rs.getInt("parentid"));
			
			list.add(bvo);
		}
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
		System.out.println("BoardDAO.queryByParentid");
	}
//	finally{
//		DBConnection.getInstance().close(null, ps, null, rs, con);
//	}
	
	
	return list;
  }
}