简单工厂模式
属于创建型模式。
当实现类都同时继承一个父类,或者实现同一个接口时,可以试用简单工厂模式来方便的创建对象。
用户可以使用传参的方式创建对象,而不是直接操作对象。这样的好处是,用户只需要关心父类或者接口的功能,不要关心具体子类内部逻辑,有类似于面向接口开发的思维。
缺点是,如果有新的子类,需要改动工厂类的代码,不易扩展和维护,所以简单工厂模式适用于子类变动小的情景。
例子
我们创建“人”的类,人都有小便的功能,人下面又有不同的类别,男人、女人、小孩,每类人小便的方式都不同。但是我们在使用“人“的时候,不用去关心每类人是怎么创建,然后怎么小便,只需要调用工厂类,传参创建一个需要的类型,然后调用小便的方法。
uml:
代码
People接口:
<?php
/**
* Description
*
* @author tangbo<admin@tbphp.net>
*/
namespace DesignPatterns\SimpleFactory;
interface People
{
/**
* 人都有小便的功能
*/
function piss(): string;
}
Man类:
<?php
/**
* 男人
*
* @author tangbo<admin@tbphp.net>
*/
namespace DesignPatterns\SimpleFactory;
class Man implements People
{
function piss(): string
{
return '男人站着便';
}
}
Woman类:
<?php
/**
* 女人
*
* @author tangbo<admin@tbphp.net>
*/
namespace DesignPatterns\SimpleFactory;
class Woman implements People
{
function piss(): string
{
return '女人蹲着便';
}
}
Baby类:
<?php
/**
* 婴儿
*
* @author tangbo<admin@tbphp.net>
*/
namespace DesignPatterns\SimpleFactory;
class Baby implements People
{
function piss(): string
{
return '小孩尿在裤子里';
}
}
工厂类:
<?php
/**
* 简单工厂类
*
* @author tangbo<admin@tbphp.net>
*/
namespace DesignPatterns\SimpleFactory;
use Prophecy\Exception\Doubler\ClassNotFoundException;
use function class_exists;
use function in_array;
use function ucfirst;
class SimpleFactory
{
private $classList = [
'Man',
'Woman',
'Baby',
];
public function createPeople(string $class_name): People
{
$class_name = ucfirst($class_name);
$class = __NAMESPACE__ . '\\' . $class_name;
if (!in_array($class_name, $this->classList) || !class_exists($class)) {
throw new ClassNotFoundException($class, $class);
}
return new $class();
}
}
测试类:
<?php
use DesignPatterns\SimpleFactory\People;
use DesignPatterns\SimpleFactory\SimpleFactory;
use PHPUnit\Framework\TestCase;
use Prophecy\Exception\Doubler\ClassNotFoundException;
class SimpleFactoryTest extends TestCase
{
private $factory;
protected function setUp(): void
{
$this->factory = new SimpleFactory();
}
public function classList(): array
{
return [
['man'],
['woman'],
['baby'],
['Baby'],
];
}
/**
* @dataProvider classList
*/
public function testCreatePeople(string $class_name): void
{
$people = $this->factory->createPeople($class_name);
echo $people->piss() . PHP_EOL;
self::assertInstanceOf(People::class, $people);
}
public function badClassList(): array
{
return [
['badman'],
['People'],
['people'],
['superman'],
];
}
/**
* @dataProvider badClassList
*/
public function testBadPeople(string $class_name): void
{
$this->expectException(ClassNotFoundException::class);
$this->factory->createPeople($class_name);
}
}
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