目的
对比简单工厂模式的优点是，您可以将其子类用不同的方法来创建一个对象。
举一个简单的例子，这个抽象类可能只是一个接口。
这种模式是「真正」的设计模式， 因为他实现了 S.O.L.I.D 原则中「D」的 「依赖倒置」。
这意味着工厂方法模式取决于抽象类，而不是具体的类。 这是与简单工厂模式和静态工厂模式相比的优势。
代码
Logger.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
interface Logger
{
public function log(string $message);
}
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StdoutLogger.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
class StdoutLogger implements Logger
{
public function log(string $message)
{
echo $message;
}
}
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FileLogger.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
class FileLogger implements Logger
{
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);
}
}
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LoggerFactory.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
interface LoggerFactory
{
public function createLogger(): Logger;
}
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StdoutLoggerFactory.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
class StdoutLoggerFactory implements LoggerFactory
{
public function createLogger(): Logger
{
return new StdoutLogger();
}
}
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FileLoggerFactory.php
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| <?php
namespace DesignPatterns\Creational\FactoryMethod;
class FileLoggerFactory implements LoggerFactory
{
private $filePath;
public function __construct(string $filePath)
{
$this->filePath = $filePath;
}
public function createLogger(): Logger
{
return new FileLogger($this->filePath);
}
}
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测试
Tests/FactoryMethodTest.php
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| <?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);
}
}
|