JDBC操作mysql数据库

@Test
    public void test2(){
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test";
            String passWord = "123456";
            String username = "root";
            //通过url和数据库用户名密码获取连接
            connection = DriverManager.getConnection(url, username, passWord);
            //设置sql语句
            String sql = "select * from `user` where id < ?";
            //获取preparedStatement
            preparedStatement = connection.prepareStatement(sql);
            //设置预处理的值
            preparedStatement.setInt(1,3);
            //执行查询 返回结果集
            resultSet = preparedStatement.executeQuery();
            ResultSetMetaData metaData = resultSet.getMetaData();
            if (resultSet.next()){
                for (int i = 1; i <=metaData.getColumnCount(); i++) {
                    //获取列名和列值   注意下标要从1开始
                    System.out.print(metaData.getColumnName(i)+"  ");
                    System.out.println(resultSet.getObject(i));
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

id  1
username  zhangsan
password  123
name  张三