建造者模式,主要用來建立複雜的物件,就有點像是大頭菜的功能組成,從鈴錢價格、組合數量、現場實價 ... 等等,為了簡化把每個功能都去不斷地建立物件、塞入物件的動作,因此可以指派一個建造者,並且賦予建造模式,然後透過指定的方法來建造物件,你不需要歷經繁瑣的過程,就能獲得擁有複雜功能的物件。
在寫建造者之前,我們需要先把很複雜的大頭菜給做出來,為了把大頭菜變複雜,所以把價格(Price)以及數量(Count)抽離出來做成物件。
Price.php
/**
* Class Price.
*/
class Price
{
/**
* @var int
*/
protected int $price = 0;
/**
* Price constructor.
*
* @param int $price
*/
public function __construct(int $price)
{
$this->set($price);
}
/**
* @return int
*/
public function get(): int
{
return $this->price;
}
/**
* @param int $price
*/
public function set(int $price)
{
$this->price = $price;
}
}
Count.php
/**
* Class Count.
*/
class Count
{
/**
* @var int
*/
protected int $price = 0;
/**
* Price constructor.
*
* @param int $price
*/
public function __construct(int $count)
{
$this->set($count);
}
/**
* @return int
*/
public function get(): int
{
return $this->count;
}
/**
* @param int $count
*/
public function set(int $count)
{
$this->count = $count;
}
}
再來要建立大頭菜,大頭菜會有個原型(Prototype),然後建立健康的大頭菜、壞掉的大頭菜,並且引用大頭菜原型。
TurnipsPrototype.php
/**
* Class TurnipsPrototype.
*/
abstract class TurnipsPrototype
{
/**
* @var Price
*/
protected Price $price;
/**
* @var Count
*/
protected Count $count;
abstract public function calculatePrice(): int;
/**
* @param int $price
*/
public function setPrice(int $price)
{
$this->price = new Price($price);
}
/**
* @param int $count
*/
public function setCount(int $count)
{
$this->count = new Count($count);
}
}
Turnips.php
/**
* Class Turnips.
*/
class Turnips extends TurnipsPrototype
{
/**
* @return int
*/
public function calculatePrice(): int
{
if (isset($this->price) && isset($this->count)) {
return $this->price->get() * $this->count->get();
} else {
return 0;
}
}
}
SpoiledTurnips.php
/**
* Class SpoiledTurnips.
*/
class SpoiledTurnips extends TurnipsPrototype
{
/**
* @return int
*/
public function calculatePrice(): int
{
if (isset($this->price) && isset($this->count)) {
return 0 * $this->count->get();
} else {
return 0;
}
}
}
我們已經把好像很複雜,但沒那麼複雜的大頭菜給定義出來了,接下來我們要建立建造者,建造者的工作就是負責把沒那麼複雜的大頭菜給建立出來,所以我們要先定義建造者的介面 Interface,並且建立健康的大頭菜建造者、壞掉的大頭菜建造者,並且去實作建造者的功能。
BuilderContract.php
/**
* Interface BuilderContract.
*/
interface BuilderContract
{
public function createTurnips();
public function setPrice(int $price);
public function setCount(int $count);
public function getTurnips(): TurnipsPrototype;
}
TurnipsBuilder.php
/**
* Class TurnipsBuilder.
*/
class TurnipsBuilder implements BuilderContract
{
/**
* @var Turnips
*/
protected Turnips $turnips;
/**
*
*/
public function createTurnips()
{
$this->turnips = new Turnips();
}
/**
* @param int $price
*/
public function setPrice(int $price)
{
$this->turnips->setPrice($price);
}
/**
* @param int $count
*/
public function setCount(int $count)
{
$this->turnips->setCount($count);
}
/**
* @return Turnips
*/
public function getTurnips(): Turnips
{
return $this->turnips;
}
}
SpoiledTurnipsBuilder.php
/**
* Class SpoiledTurnipsBuilder.
*/
class SpoiledTurnipsBuilder implements BuilderContract
{
/**
* 壞掉的大頭菜是沒辦法賣鈴錢的狸!
*
* @var int
*/
const SPOILED_PRICE = 0;
/**
* @var SpoiledTurnips
*/
protected SpoiledTurnips $turnips;
/**
*
*/
public function createTurnips()
{
$this->turnips = new SpoiledTurnips();
}
/**
* @param int $price
*/
public function setPrice(int $price)
{
$this->turnips->setPrice($price);
}
/**
* @param int $count
*/
public function setCount(int $count)
{
$this->turnips->setCount(self::SPOILED_PRICE);
}
/**
* @return SpoiledTurnips
*/
public function getTurnips(): SpoiledTurnips
{
return $this->turnips;
}
}
最後我們要製作 Director
來負責控制建造者,只要把大頭菜建造者丟進去,大頭菜建造者就會開始製作大頭菜,並且把大頭菜丟出來給我們,而製造大頭菜這之間的過程,我們都不需要操心。
Director.php
/**
* Class Director.
*/
class Director
{
/**
* @param BuilderContract $builder
* @param int $price
* @param int $count
*
* @return TurnipsPrototype
*/
public function build(BuilderContract $builder, int $price, int $count): TurnipsPrototype
{
$builder->createTurnips();
$builder->setPrice($price);
$builder->setCount($count);
return $builder->getTurnips();
}
}
最後我們要對我們的大頭菜建造者做幾些測試,主要的測試項目如下:
BuilderPatternTest.php
/**
* Class BuilderPatternTest.
*/
class BuilderPatternTest extends TestCase
{
/**
* 測試是否能夠正常建立大頭菜。
*
* @test
*/
public function test_can_build_turnips()
{
$builder = new TurnipsBuilder();
$turnips = (new Director())->build($builder, 100, 40);
$this->assertInstanceOf(Turnips::class, $turnips);
}
/**
* 測試是否能夠正常建立壞掉的大頭菜。
*
* @test
*/
public function test_can_build_spoiled_turnips()
{
$builder = new SpoiledTurnipsBuilder();
$turnips = (new Director())->build($builder, 100, 40);
$this->assertInstanceOf(SpoiledTurnips::class, $turnips);
}
/**
* 測試大頭菜是否能夠正常計算價格。
*
* @test
*/
public function test_can_calculate_price_for_turnips()
{
$builder = new TurnipsBuilder();
$turnips = (new Director())->build($builder, 100, 40);
$this->assertEquals(4000, $turnips->calculatePrice());
}
/**
* 測試壞掉的大頭菜是否能夠正常計算價格。
*
* @test
*/
public function test_can_calculate_price_for_spoiled_turnips()
{
$builder = new SpoiledTurnipsBuilder();
$turnips = (new Director())->build($builder, 100, 40);
$this->assertEquals(0, $turnips->calculatePrice());
}
}
最後測試的執行結果會獲得如下:
PHPUnit Pretty Result Printer 0.28.0 by Codedungeon and contributors.
==> Configuration: ~/php-design-pattern/vendor/codedungeon/phpunit-result-printer/src/phpunit-printer.yml
PHPUnit 9.2.6 by Sebastian Bergmann and contributors.
==> AbstractFactoryTest ✔ ✔ ✔ ✔
==> BuilderPatternTest ✔ ✔ ✔ ✔
==> FactoryMethodTest ✔ ✔ ✔ ✔
==> PoolPatternTest ✔ ✔
==> PrototypePatternTest ✔ ✔
==> SimpleFactoryTest ✔ ✔ ✔ ✔
==> SingletonPatternTest ✔
==> StaticFactoryTest ✔ ✔ ✔ ✔ ✔
Time: 00:00.050, Memory: 6.00 MB
OK (26 tests, 70 assertions)