结合PDO和DAO模式

Question

PHP的PDO功能和DAO模式如何混合？我应该有一个初始化数据库连接的抽象类吗？PDO可以被认为与Java的JDBC等效吗？

Answer 1

是的,PDO几乎是JDBC的"等价",但在PHP中.

您应该在域对象的构造函数中传递PDO的实例(依赖注入):

abstract class Object {
    protected $_pdo;

    protected $_target;

    public function __construct(PDO $pdo) {
        $this->_pdo = $pdo;
    }

    public function load($id) {
        // $this->_pdo->something()
    }

    public function save() {
        // $this->_pdo->something()
    }

    public function delete() {
        // $this->_pdo->something()
    }
}

class User extends Object {
    protected $_target = 'user_table';

    public $name;
}

然后:

$pdo = new PDO('mysql:dbname=foobar');
$user = new User($pdo);
$user->name = 'netcoder';
$user->save();

您还可以添加静态方法Object来指定默认实例:

class Object {
    // ...

    static protected $_defaultPDO;

    static public function setDefaultPDO(PDO $pdo) {
        self::$_defaultPDO = $pdo;
    }

    public function __construct(PDO $pdo = null) {
        if (!isset($pdo)) $pdo = self::$_defaultPDO;
        if (!isset($pdo))
            throw new DomainException('No default PDO object defined');

        $this->_pdo = $pdo;
    }
}

Object::setDefaultPDO(new PDO('mysql:dbname=foobar'));
$user = new User;
$user->name = 'James P.';
$user->save();