我已创建三类。一类是从PDO扩展的db。其他两个类从db类扩展。但问题是当我初始化这些子类的对象时,第二个对象被创建为第一个对象的克隆。预先感谢您的帮助。错误时PDO类扩展
<?php
/** The Database Driver */
define('DB_DRIVER', 'mysql');
/** The name of the database */
define('DB_NAME', 'sample');
/** MySQL database username */
define('DB_USER', 'root');
/** MySQL database password */
define('DB_PASSWORD', 'root');
/** MySQL hostname */
define('DB_HOST', 'localhost');
class db extends PDO
{
public function __construct()
{
echo "DB constructor called\n";
$options = array(
PDO::ATTR_PERSISTENT => true,
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
$dsn = DB_DRIVER . ":host=" . DB_HOST . ";dbname=" . DB_NAME;
parent::__construct($dsn, DB_USER, DB_PASSWORD, $options);
}
}
class Admin extends db
{
private $uid, $username, $password, $level, $name, $email;
public function __construct()
{
echo "Admin constructor called\n";
parent::__construct();
}
}
class Movie extends db
{
private $mid, $title, $slug;
public function __construct()
{
echo "Movie constructor called\n";
parent::__construct();
}
}
$adminObj = new Admin();
$movieObj = new Movie();
var_dump($adminObj);
var_dump($movieObj);
?>
下面是上述的输出。 请注意输出中显示的对象类型。
Admin constructor called
DB constructor called
Movie constructor called
DB constructor called
object(Admin)#1 (6) {
["uid":"Admin":private]=>
NULL
["username":"Admin":private]=>
NULL
["password":"Admin":private]=>
NULL
["level":"Admin":private]=>
NULL
["name":"Admin":private]=>
NULL
["email":"Admin":private]=>
NULL
}
object(Admin)#2 (6) {
["uid":"Admin":private]=>
NULL
["username":"Admin":private]=>
NULL
["password":"Admin":private]=>
NULL
["level":"Admin":private]=>
NULL
["name":"Admin":private]=>
NULL
["email":"Admin":private]=>
NULL
}
当父:: __构建体($ DSN,DB_USER,DB_PASSWORD,$选项);在db类中被删除的问题会消失。
如果您不满意提出的方案和需要持久连接,那么(好,我会建议它在任何情况下)根本不延长PDO和创建'db'类中PDO实例,而不是或通行PDO实例作为Admin/Movie类构造函数的参数。 – LazyOne 2011-06-10 18:55:16