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Archives for 3 月 2020

PHP教學 – 依賴注入容器

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依賴注入容器常見的幾種方式

  • 建構子注入(Constructor Injection
  • Setter注入(Setter Injection)
  • 介面注入(Interface Injection)

建構子注入

建構子注入必須在建立物件實體時就進行注入。

class Application
{
    private $auth;
    private $session;
    public function __construct(Auth $auth, Session $session)
    {
        $this->auth    = $auth;
        $this->session = $session;
    }
    // ...程式...
}
$auth        = new Auth('localhost', 'root', '');
$session     = new Session();
$application = new Application($auth, $session);
 
$application->login('admin', 'admin');

Setter注入

Setter注入則是可以在物件實體建立後才透過 setter 函式來進行注入。 

class Application
{
    private $auth;
    private $session;
    public function SetAuth(Auth $_oAuth)
    {
        $this->auth = $_oAuth;
    }
    public function SetSession(Session $_oSession)
    {
        $this->session = $_oSession;
    }
    // ...程式...
}
$auth        = new Auth('localhost', 'root', '');
$session     = new Session();
$application = new Application();
$application ->SetAuth($auth);
$application ->SetSession($authsession);
 
$application->login('admin', 'admin');

介面注入

透過Interface去實作Setter。 

interface Setter
{
    public function SetAuth(Auth $_oAuth);
    public function SetSession(Session $_oSession);
}
class Application implements Setter
{
    private $auth;
    private $session;
    public function SetAuth(Auth $_oAuth)
    {
        $this->auth = $_oAuth;
    }
    public function SetSession(Session $_oSession)
    {
        $this->session = $_oSession;
    }
    // ...程式...
}
$auth        = new Auth('localhost', 'root', '');
$session     = new Session();
$application = new Application();
$application ->SetAuth($auth);
$application ->SetSession($authsession);
 
$application->login('admin', 'admin');

何種比較好?

常見的建構元注入跟Setter注入哪種比較好?

It’s important to support both mechanisms, even if there’s a preference for one of them.
—— Martin Fowler

即使你有較偏好的選擇，同時支持這兩種機制都是必要的。

interface Setter
{
    public function SetAuth(Auth $_oAuth);
    public function SetSession(Session $_oSession);
}
class Application implements Setter
{
    private $auth;
    private $session;
    public function __construct(Auth $auth, Session $session)
    {
        $this->auth    = $auth;
        $this->session = $session;
    }
    public function SetAuth(Auth $_oAuth)
    {
        $this->auth = $_oAuth;
    }
    public function SetSession(Session $_oSession)
    {
        $this->session = $_oSession;
    }
    // ...程式...