3.9.1. 目的
状态模式可以基于一个对象的同种事务而封装出不同的行为。它提供一种简洁的方式使得对象在运行时可以改变自身行为，而不必借助单一庞大的条件判断语句。
3.9.2. UML 类图
3.9.3. 代码
你可以在 GitHub 上找到这些代码
ContextOrder.php
namespace DesignPatterns\Behavioral\State;
class ContextOrder extends StateOrder
{
public function getState():StateOrder
{
return static::$state;
}
public function setState(StateOrder $state)
{
static::$state = $state;
}
public function done()
{
static::$state->done();
}
public function getStatus(): string
{
return static::$state->getStatus();
}
}
StateOrder.php
namespace DesignPatterns\Behavioral\State;
abstract class StateOrder
{
/**
* @var array
*/
private $details;
/**
* @var StateOrder $state
*/
protected static $state;
/**
* @return mixed
*/
abstract protected function done();
protected function setStatus(string $status)
{
$this->details['status'] = $status;
$this->details['updatedTime'] = time();
}
protected function getStatus(): string
{
return $this->details['status'];
}
}
ShippingOrder.php
namespace DesignPatterns\Behavioral\State;
class ShippingOrder extends StateOrder
{
public function __construct()
{
$this->setStatus('shipping');
}
protected function done()
{
$this->setStatus('completed');
}
}
CreateOrder.php
namespace DesignPatterns\Behavioral\State;
class CreateOrder extends StateOrder
{
public function __construct()
{
$this->setStatus('created');
}
protected function done()
{
static::$state = new ShippingOrder();
}
}
3.9.4. 测试
Tests/StateTest.php
namespace DesignPatterns\Behavioral\State\Tests;
use DesignPatterns\Behavioral\State\ContextOrder;
use DesignPatterns\Behavioral\State\CreateOrder;
use PHPUnit\Framework\TestCase;
class StateTest extends TestCase
{
public function testCanShipCreatedOrder()
{
$order = new CreateOrder();
$contextOrder = new ContextOrder();
$contextOrder->setState($order);
$contextOrder->done();
$this->assertEquals('shipping', $contextOrder->getStatus());
}
public function testCanCompleteShippedOrder()
{
$order = new CreateOrder();
$contextOrder = new ContextOrder();
$contextOrder->setState($order);
$contextOrder->done();
$contextOrder->done();
$this->assertEquals('completed', $contextOrder->getStatus());
}
}
