java web留言板-带数据库

package com.lyb.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.Vector; import com.lyb.po.Message; import com.lyb.po.User; public class MsgDAO { Connection conn=null; Statement stmt=null; PreparedStatement pstmt=null; ResultSet rs=null; public MsgDAO() { conn=DBConn.getConn("sa", ""); } public int insertDB(Message msg) { int flag=0; try { pstmt=conn.prepareStatement("insert into Message(user_Id,msg_Time,msg_Subject,msg_Content) values(?,?,?,?)"); pstmt.setInt(1, msg.getUserId()); pstmt.setString(2, msg.getMsgTime()); pstmt.setString(3, msg.getMsgSubject()); pstmt.setString(4, msg.getMsgContent()); flag=pstmt.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { pstmt.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return flag; } public Vector<Message> selectDB() { Vector<Message> v=new Vector<Message>(); Message msg=null; try { stmt=conn.createStatement(); rs=stmt.executeQuery("select * from Message left join Users on Message.user_Id=Users.user_Id order by msg_Time Desc"); while(rs.next()) { msg=new Message(); User u=new User(); msg.setUserId(rs.getInt(2)); msg.setMsgTime(rs.getString(3)); msg.setMsgSubject(rs.getString(4)); msg.setMsgContent(rs.getString(5)); u.setUserName(rs.getString(7)); msg.setUser(u); v.addElement(msg); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { rs.close(); stmt.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return v; } public void closeDB() { try { conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }