public void deleteAll() throws SQLException, ClassNotFoundException {
 
    Connection c = connectionMaker.makeNewConnection();
    PreparedStatement ps = c.prepareStatement("DELETE FROM users");

    ps.executeUpdate();

    // 사용한 리소스를 반드시 반환해야한다
    ps.close();
    c.close();
}

public void deleteAll() throws SQLException, ClassNotFoundException {
    Connection c = null;
    PreparedStatement ps = null;
    try {
        c = connectionMaker.makeNewConnection();
        ps = c.prepareStatement("DELETE FROM users");

        ps.executeUpdate();

    } catch (SQLException e){
        throw e;

    } finally {
        if(ps != null){
            try {
                ps.close();
            } catch (SQLException e){
                throw e;
            }
        }
        if(c != null){
            try {
                c.close();
            } catch (SQLException e){
                throw e;
            }
        }
    }
}

public void deleteAll() throws SQLException, ClassNotFoundException {
        Connection c = null;
        PreparedStatement ps = null;
        try {
            // 코드 변하는 부분
            // 변하는 코드 전, 후가 변하지 않는다
            
        } catch (SQLException e){
            throw e;

        } finally {
            if(ps != null){
                try {
                    ps.close();
                } catch (SQLException e){
                    throw e;
                }
            }
            if(c != null){
                try {
                    c.close();
                } catch (SQLException e){
                    throw e;
                }
            }
        }
    }

c = connectionMaker.makeNewConnection();
ps = c.prepareStatement("DELETE FROM users");

ps.executeUpdate();

public void deleteAll() throws SQLException, ClassNotFoundException {
    StatementStrategy st = new DeleteAllStatement();        // 전략 오브젝트 생성
    jdbcContextWithStatementStrategy(st);                   // 컨텍스트는 전략 오브젝트 제공받음
    }

public void deleteAll() throws SQLException, ClassNotFoundException {
//        StatementStrategy st = new DeleteAllStatement();        // 전략 오브젝트 생성
    // 익명 클래스를 이용한 바로 구현
    StatementStrategy st = new StatementStrategy() {
        @Override
        public PreparedStatement makePreparedStatement(Connection c) throws SQLException 		{
            PreparedStatement ps = c.prepareStatement("DELETE FROM users");
            return ps;
        }
    };
    jdbcContextWithStatementStrategy(st);               // 컨텍스트는 전략 오브젝트 제공받음
}

public void deleteAll(){
    // Spring에서 지원해주는 Jdbc Template 사용
    this.jdbcTemplate.update("DELETE FROM users");
}

// 쿼리에 바인딩하는 방법
public void add(User user){
    // Spring에서 지원해주는 Jdbc Template 사용
    this.jdbcTemplate.update("INSERT INTO users(id, name, password) VALUES(?,?,?)",
                             							user.getId(), user.getName(), user.getPassword());
}

// 1 -> 일반 query 메소드를 사용했을 때
public int getCount(){
    return this.jdbcTemplate.query(new PreparedStatementCreator() {
        @Override
        public PreparedStatement createPreparedStatement(Connection con) throws SQLException {
            return con.prepareStatement("SELECT COUNT(*) FROM users");
        }
    }, new ResultSetExtractor<Integer>() {
        @Override
        public Integer extractData(ResultSet rs) throws SQLException, DataAccessException {
            rs.next();
            return rs.getInt(1);
        }
    });
}

// 2
public int getCount(){
    return this.jdbcTemplate.queryForObject("SELECT COUNT(*) FROM users", Integer.TYPE);
}

public User get(String id){
    return this.jdbcTemplate.queryForObject("SELECT * FROM users WHERE id = ?",
                                            new Object[]{id},
                                            new RowMapper<User>() {
                                                @Override
                                                public User mapRow(ResultSet rs, int rowNum) throws SQLException {
                                                    User user = new User();
                                                    user.setId(rs.getString("id"));
                                                    user.setName(rs.getString("name"));
                                                    user.setPassword(rs.getString("password"));
                                                    return user;
                                                }
                                            }
                                           );
    }

public List<User> getAll() {
    return this.jdbcTemplate.query("SELECT * FROM users ORDER BY id",
                                   new RowMapper<User>() {
                                       @Override
                                       public User mapRow(ResultSet rs, int rowNum) throws SQLException {
                                           User user = new User();
                                           user.setId(rs.getString("id"));
                                           user.setName(rs.getString("name"));
                                           user.setPassword(rs.getString("password"));
                                           return user;
                                       }
                                   });
}