Purpose:
Builder is an interface that build parts of a complex object.
Sometimes, if the builder has a better knowledge of what it builds, this interface could be an abstract class with default methods.
If you have a complex inheritance tree for objects, it is logical to have a complex inheritance tree for builders too.
在这个模式里面，Director 只需要接收一个builder，并且指挥builder去做事情，最后返回一个Vehicle。在builder class里面，定义了如何去做事情。
如果没有Director，在我们每次想得到不同Vehicle Instance之前，都得让builder去做一遍Director里定义的方法。
Director.php
<?php
namespace DesignPatterns\Creational\Builder;
use DesignPatterns\Creational\Builder\Parts\Vehicle;
/**
* Director is part of the builder pattern. It knows the interface of the builder
* and builds a complex object with the help of the builder
*
* You can also inject many builders instead of one to build more complex objects
*/
class Director
{
public function build(BuilderInterface $builder): Vehicle
{
$builder->createVehicle();
$builder->addDoors();
$builder->addEngine();
$builder->addWheel();
return $builder->getVehicle();
}
}
BuilderInterface.php
<?php
namespace DesignPatterns\Creational\Builder;
use DesignPatterns\Creational\Builder\Parts\Vehicle;
interface BuilderInterface
{
public function createVehicle();
public function addWheel();
public function addEngine();
public function addDoors();
public function getVehicle(): Vehicle;
}
TruckBuilder.php
<?php
namespace DesignPatterns\Creational\Builder;
use DesignPatterns\Creational\Builder\Parts\Vehicle;
class TruckBuilder implements BuilderInterface
{
/**
* @var Parts\Truck
*/
private $truck;
public function addDoors()
{
$this->truck->setPart('rightDoor', new Parts\Door());
$this->truck->setPart('leftDoor', new Parts\Door());
}
public function addEngine()
{
$this->truck->setPart('truckEngine', new Parts\Engine());
}
public function addWheel()
{
$this->truck->setPart('wheel1', new Parts\Wheel());
$this->truck->setPart('wheel2', new Parts\Wheel());
$this->truck->setPart('wheel3', new Parts\Wheel());
$this->truck->setPart('wheel4', new Parts\Wheel());
$this->truck->setPart('wheel5', new Parts\Wheel());
$this->truck->setPart('wheel6', new Parts\Wheel());
}
public function createVehicle()
{
$this->truck = new Parts\Truck();
}
public function getVehicle(): Vehicle
{
return $this->truck;
}
}
CarBuilder.php
<?php
namespace DesignPatterns\Creational\Builder;
use DesignPatterns\Creational\Builder\Parts\Vehicle;
class CarBuilder implements BuilderInterface
{
/**
* @var Parts\Car
*/
private $car;
public function addDoors()
{
$this->car->setPart('rightDoor', new Parts\Door());
$this->car->setPart('leftDoor', new Parts\Door());
$this->car->setPart('trunkLid', new Parts\Door());
}
public function addEngine()
{
$this->car->setPart('engine', new Parts\Engine());
}
public function addWheel()
{
$this->car->setPart('wheelLF', new Parts\Wheel());
$this->car->setPart('wheelRF', new Parts\Wheel());
$this->car->setPart('wheelLR', new Parts\Wheel());
$this->car->setPart('wheelRR', new Parts\Wheel());
}
public function createVehicle()
{
$this->car = new Parts\Car();
}
public function getVehicle(): Vehicle
{
return $this->car;
}
}
Parts/Vehicle.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
abstract class Vehicle
{
/**
* @var object[]
*/
private $data = [];
/**
* @param string $key
* @param object $value
*/
public function setPart($key, $value)
{
$this->data[$key] = $value;
}
}
Parts/Truck.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
class Truck extends Vehicle
{
}
Parts/Car.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
class Car extends Vehicle
{
}
Parts/Engine.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
class Engine
{
}
Parts/Wheel.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
class Wheel
{
}
Parts/Door.php
<?php
namespace DesignPatterns\Creational\Builder\Parts;
class Door
{
}
Tests/DirectorTest.php
<?php
namespace DesignPatterns\Creational\Builder\Tests;
use DesignPatterns\Creational\Builder\Parts\Car;
use DesignPatterns\Creational\Builder\Parts\Truck;
use DesignPatterns\Creational\Builder\TruckBuilder;
use DesignPatterns\Creational\Builder\CarBuilder;
use DesignPatterns\Creational\Builder\Director;
use PHPUnit\Framework\TestCase;
class DirectorTest extends TestCase
{
public function testCanBuildTruck()
{
$truckBuilder = new TruckBuilder();
$newVehicle = (new Director())->build($truckBuilder);
$this->assertInstanceOf(Truck::class, $newVehicle);
}
public function testCanBuildCar()
{
$carBuilder = new CarBuilder();
$newVehicle = (new Director())->build($carBuilder);
$this->assertInstanceOf(Car::class, $newVehicle);
}
}