JDBC 增删改查
public class NoteDAOImpl implements NoteDAO {  
    // 增加操作  
    public void insert(Note note) throws Exception {  
        String sql = "INSERT INTO note(id,title,author,content) VALUES(note_sequ.nextVal,?,?,?)" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setString(1,note.getTitle()) ;  
            pstmt.setString(2,note.getAuthor()) ;  
            pstmt.setString(3,note.getContent()) ;  
            pstmt.executeUpdate() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            // System.out.println(e) ;  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
    }  
    // 修改操作  
    public void update(Note note) throws Exception {  
        String sql = "UPDATE note SET title=?,author=?,content=? WHERE id=?" ;  
        PreparedStatement pstmt = null ;  
        DataBaseConnection dbc = null ;  
        dbc = new DataBaseConnection() ;  
        try {  
            pstmt = dbc.getConnection().prepareStatement(sql) ;  
            pstmt.setString(1,note.getTitle()) ;  
            pstmt.setString(2,note.getAuthor()) ;  
            pstmt.setString(3,note.getContent()) ;  
            pstmt.setInt(4,note.getId()) ;  
            pstmt.executeUpdate() ;  
            pstmt.close() ;  
        } catch (Exception e) {  
            throw new Exception("操作中出现错误！！！") ;  
        } finally {  
            dbc.close() ;  
        }  
    }  
    // 删除操作  
 &nbs