目的

這種模式提供了一種簡單的解耦多組件之間的協(xié)同工作方式。如果你有一個“智能中心”，比如控制器（但不是 MVC 的意義上），它是觀察者的一個很好的替代品。

所有組件（稱為同事）僅與 Mediator 接口耦合，這是一件好事，因為在 OOP 中，一個好朋友勝過多個。這是這種模式的關(guān)鍵特征。

UML 圖

代碼

Mediator.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\Mediator;

interface Mediator
{
    public function getUser(string $username): string;
}

Colleague.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\Mediator;

abstract class Colleague
{
    protected Mediator $mediator;

    public function setMediator(Mediator $mediator)
    {
        $this->mediator = $mediator;
    }
}

Ui.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\Mediator;

class Ui extends Colleague
{
    public function outputUserInfo(string $username)
    {
        echo $this->mediator->getUser($username);
    }
}

UserRepository.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\Mediator;

class UserRepository extends Colleague
{
    public function getUserName(string $user): string
    {
        return 'User: ' . $user;
    }
}

UserRepositoryUiMediator.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\Mediator;

class UserRepositoryUiMediator implements Mediator
{
    public function __construct(private UserRepository $userRepository, private Ui $ui)
    {
        $this->userRepository->setMediator($this);
        $this->ui->setMediator($this);
    }

    public function printInfoAbout(string $user)
    {
        $this->ui->outputUserInfo($user);
    }

    public function getUser(string $username): string
    {
        return $this->userRepository->getUserName($username);
    }
}

測試

Tests/MediatorTest.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Tests\Mediator\Tests;

use DesignPatterns\Behavioral\Mediator\Ui;
use DesignPatterns\Behavioral\Mediator\UserRepository;
use DesignPatterns\Behavioral\Mediator\UserRepositoryUiMediator;
use PHPUnit\Framework\TestCase;

class MediatorTest extends TestCase
{
    public function testOutputHelloWorld()
    {
        $mediator = new UserRepositoryUiMediator(new UserRepository(), new Ui());

        $this->expectOutputString('User: Dominik');
        $mediator->printInfoAbout('Dominik');
    }
}