public static void main(String[] args) throws SQLException {

    String url = "jdbc:mysql://127.0.0.1:3306/student";
    String userName = "root";
    String password = "11111";
    String sql = "select id,name,age from user;";

    // 1.建立连接
    Connection connection = DriverManager.getConnection(url, userName, password);

    // 2.具体操作
    // 2.1 预编译 SQL
    PreparedStatement statement = connection.prepareStatement(sql);
    // 2.2 执行查询
    ResultSet resultSet = statement.executeQuery();
    // 2.3 处理结果集
    while (resultSet.next()) {
        int id = resultSet.getInt("id");
        String name = resultSet.getString("name");
        int age = resultSet.getInt("age");
        System.out.println("id = " + id + ", name=" + name + ", age=" + age);
    }

    // 3.资源关闭
    resultSet.close();
    statement.close();
    connection.close();
}