1.3.1. 目的

對比簡單工廠模式的優(yōu)點是，您可以將其子類用不同的方法來創(chuàng)建一個對象理朋。

舉一個簡單的例子绩蜻，這個抽象類可能只是一個接口铣墨。

這種模式是「真正」的設(shè)計模式， 因為他實現(xiàn)了 S.O.L.I.D 原則中「D」的 「依賴倒置」办绝。

這意味著工廠方法模式取決于抽象類伊约，而不是具體的類。 這是與簡單工廠模式和靜態(tài)工廠模式相比的優(yōu)勢孕蝉。

1.3.2. UML 圖

1.3.3. 代碼

你可以在??GitHub?查看這段代碼

Logger.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
interface Logger
{
    public function log(string $message);
}

StdoutLogger.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
class StdoutLogger implements Logger
{
    public function log(string $message)
    {
        echo $message;
    }
}

FileLogger.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
class FileLogger implements Logger
{
    /**
     * @var string
     */
    private $filePath;
    public function __construct(string $filePath)
    {
        $this->filePath = $filePath;
    }
    public function log(string $message)
    {
        file_put_contents($this->filePath, $message . PHP_EOL, FILE_APPEND);
    }
}

LoggerFactory.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
interface LoggerFactory
{
    public function createLogger(): Logger;
}

StdoutLoggerFactory.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
class StdoutLoggerFactory implements LoggerFactory
{
    public function createLogger(): Logger
    {
        return new StdoutLogger();
    }
}

FileLoggerFactory.php

<?php
namespace DesignPatterns\Creational\FactoryMethod;
class FileLoggerFactory implements LoggerFactory
{
    /**
     * @var string
     */
    private $filePath;
    public function __construct(string $filePath)
    {
        $this->filePath = $filePath;
    }
    public function createLogger(): Logger
    {
        return new FileLogger($this->filePath);
    }
}

1.3.4. 測試

Tests/FactoryMethodTest.php

<?php
namespace DesignPatterns\Creational\FactoryMethod\Tests;
use DesignPatterns\Creational\FactoryMethod\FileLogger;
use DesignPatterns\Creational\FactoryMethod\FileLoggerFactory;
use DesignPatterns\Creational\FactoryMethod\StdoutLogger;
use DesignPatterns\Creational\FactoryMethod\StdoutLoggerFactory;
use PHPUnit\Framework\TestCase;
class FactoryMethodTest extends TestCase
{
    public function testCanCreateStdoutLogging()
    {
        $loggerFactory = new StdoutLoggerFactory();
        $logger = $loggerFactory->createLogger();
        $this->assertInstanceOf(StdoutLogger::class, $logger);
    }
    public function testCanCreateFileLogging()
    {
        $loggerFactory = new FileLoggerFactory(sys_get_temp_dir());
        $logger = $loggerFactory->createLogger();
        $this->assertInstanceOf(FileLogger::class, $logger);
    }
}