我已经使用了三个类。两个类扩展了第三个类db。但问题是，当我声明这些类的对象时，第二个对象被创建为第一个对象的克隆。提前感谢您的帮助。
class db extends PDO {
public function __construct() {
echo "DB constructor called'n";
..
}
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();
}
$base_path = "../../";
require $base_path . 'config.php';
require $base_path . 'lib/class.db.php';
require $base_path . 'lib/Admin.php';
require $base_path . 'lib/Movie.php';
$adminObj = new Admin();
$movieObj = new Movie();
var_dump($adminObj);
var_dump($movieObj);
输出为
Admin constructor called
DB constructor called
Movie constructor called
DB constructor called
object(Admin)#1 (11) {
["uid":"Admin":private]=>
NULL
["username":"Admin":private]=>
NULL
["password":"Admin":private]=>
NULL
["level":"Admin":private]=>
NULL
["name":"Admin":private]=>
NULL
["email":"Admin":private]=>
NULL
["error":"db":private]=>
NULL
["sql":"db":private]=>
NULL
["bind":"db":private]=>
NULL
["errorCallbackFunction":"db":private]=>
NULL
["errorMsgFormat":"db":private]=>
NULL
}
object(Admin)#2 (11) {
["uid":"Admin":private]=>
NULL
["username":"Admin":private]=>
NULL
["password":"Admin":private]=>
NULL
["level":"Admin":private]=>
NULL
["name":"Admin":private]=>
NULL
["email":"Admin":private]=>
NULL
["error":"db":private]=>
NULL
["sql":"db":private]=>
NULL
["bind":"db":private]=>
NULL
["errorCallbackFunction":"db":private]=>
NULL
["errorMsgFormat":"db":private]=>
NULL
}
修改后的代码，请对此进行分析。当父级：：__construct（$dsn，DB_USER，DB_PASSWORD，$options）；删除db类后，问题将消失。
<?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);
?>
我没有看到任何问题——输出完全符合预期。因此，它一定是一个错误的其他地方，你正在包括的文件。以下是独立测试代码：
<?php
class db extends PDO
{
public function __construct()
{
echo "DB constructor called'n";
}
}
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);
这就是输出：
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(Movie)#2 (3) {
["mid":"Movie":private]=>
NULL
["title":"Movie":private]=>
NULL
["slug":"Movie":private]=>
NULL
}
所以请检查您的实际代码。也许（只是也许）你包含了错误的文件。。或者第二个类在另一个地方被声明（你可能编辑了错误的文件）。。。
编辑：亚历克斯，谢谢你提供更多信息。我在您更新的代码中发现了这个问题：PDO::ATTR_PERSISTENT => true，--将true更改为false，并查看差异：）
它们不是克隆。它们都是从db类继承的，您还没有对它们进行任何更改。它们不是克隆体——它们只是完全相同。
如果要阻止2个PDO实例，请使用Singleton模式