详述PHP适配器模式（附代码示例）

namespace RefactoringGuru\Adapter\RealWorld;

/**

 * The Target interface represents the interface that your application's classes

 * already follow.

 */

interface Notification

{

    public function send(string $title, string $message);

}

/**

 * Here's an example of the existing class that follows the Target interface.

 *

 * The truth is that many real apps may not have this interface clearly defined.

 * If you're in that boat, your best bet would be to extend the Adapter from one

 * of your application's existing classes. If that's awkward (for instance,

 * SlackNotification doesn't feel like a subclass of EmailNotification), then

 * extracting an interface should be your first step.

 */

class EmailNotification implements Notification

{

    private $adminEmail;

    public function __construct(string $adminEmail)

    {

        $this->adminEmail = $adminEmail;

    }

    public function send(string $title, string $message): void

    {

        mail($this->adminEmail, $title, $message);

        echo "Sent email with title '$title' to '{$this->adminEmail}' that says '$message'.";

    }

}

/**

 * The Adaptee is some useful class, incompatible with the Target interface. You

 * can't just go in and change the code of the class to follow the Target

 * interface, since the code might be provided by a 3rd-party library.

 */

class SlackApi

{

    private $login;

    private $apiKey;

    public function __construct(string $login, string $apiKey)

    {

        $this->login = $login;

        $this->apiKey = $apiKey;

    }

    public function logIn(): void

    {

        // Send authentication request to Slack web service.

        echo "Logged in to a slack account '{$this->login}'.\n";

    }

    public function sendMessage(string $chatId, string $message): void

    {

        // Send message post request to Slack web service.

        echo "Posted following message into the '$chatId' chat: '$message'.\n";

    }

}

/**

 * The Adapter is a class that links the Target interface and the Adaptee class.

 * In this case, it allows the application to send notifications using Slack

 * API.

 */

class SlackNotification implements Notification

{

    private $slack;

    private $chatId;

    public function __construct(SlackApi $slack, string $chatId)

    {

        $this->slack = $slack;

        $this->chatId = $chatId;

    }

    /**

     * An Adapter is not only capable of adapting interfaces, but it can also

     * convert incoming data to the format required by the Adaptee.

     */

    public function send(string $title, string $message): void

    {

        $slackMessage = "#" . $title . "# " . strip_tags($message);

        $this->slack->logIn();

        $this->slack->sendMessage($this->chatId, $slackMessage);

    }

}

/**

 * The client code can work with any class that follows the Target interface.

 */

function clientCode(Notification $notification)

{

    // ...

    echo $notification->send("Website is down!",

        "Alert! " .

        "Our website is not responding. Call admins and bring it up!");

    // ...

}

echo "Client code is designed correctly and works with email notifications:\n";

$notification = new EmailNotification("developers@example.com");

clientCode($notification);

echo "\n\n";

echo "The same client code can work with other classes via adapter:\n";

$slackApi = new SlackApi("example.com", "XXXXXXXX");

$notification = new SlackNotification($slackApi, "Example.com Developers");

clientCode($notification);

Client code is designed correctly and works with email notifications:

Sent email with title 'Website is down!' to 'developers@example.com' that says 'color:red;font-size: 50px;'>Alert! Our website is not responding. Call admins and bring it up!'.

The same client code can work with other classes via adapter:

Logged in to a slack account 'example.com'.

Posted following message into the 'Example.com Developers' chat: '#Website is down!# Alert! Our website is not responding. Call admins and bring it up!'.

namespace RefactoringGuru\Adapter\Conceptual;

/**

 * The Target defines the domain-specific interface used by the client code.

 */

class Target

{

    public function request(): string

    {

        return "Target: The default target's behavior.";

    }

}

/**

 * The Adaptee contains some useful behavior, but its interface is incompatible

 * with the existing client code. The Adaptee needs some adaptation before the

 * client code can use it.

 */

class Adaptee

{

    public function specificRequest(): string

    {

        return ".eetpadA eht fo roivaheb laicepS";

    }

}

/**

 * The Adapter makes the Adaptee's interface compatible with the Target's

 * interface.

 */

class Adapter extends Target

{

    private $adaptee;

    public function __construct(Adaptee $adaptee)

    {

        $this->adaptee = $adaptee;

    }

    public function request(): string

    {

        return "Adapter: (TRANSLATED) " . strrev($this->adaptee->specificRequest());

    }

}

/**

 * The client code supports all classes that follow the Target interface.

 */

function clientCode(Target $target)

{

    echo $target->request();

}

echo "Client: I can work just fine with the Target objects:\n";

$target = new Target();

clientCode($target);

echo "\n\n";

$adaptee = new Adaptee();

echo "Client: The Adaptee class has a weird interface. See, I don't understand it:\n";

echo "Adaptee: " . $adaptee->specificRequest();

echo "\n\n";

echo "Client: But I can work with it via the Adapter:\n";

$adapter = new Adapter($adaptee);

clientCode($adapter);

Client: I can work just fine with the Target objects:

Target: The default target's behavior.

Client: The Adaptee class has a weird interface. See, I don't understand it:

Adaptee: .eetpadA eht fo roivaheb laicepS

Client: But I can work with it via the Adapter:

Adapter: (TRANSLATED) Special behavior of the Adaptee.