状态模式（State）

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。

UML 类图

file

代码

你可以在 GitHub 上找到这些代码

ContextOrder.php

  2. <?php
  4. namespace DesignPatterns\Behavioral\State;
  6. class ContextOrder extends StateOrder
  7. {
  8.     public function getState():StateOrder
  9.     {
  10.         return static::$state;
  11.     }
  13.     public function setState(StateOrder $state)
  14.     {
  15.         static::$state = $state;
  16.     }
  18.     public function done()
  19.     {
  20.         static::$state->done();
  21.     }
  23.     public function getStatus(): string
  24.     {
  25.         return static::$state->getStatus();
  26.     }
  27. }

StateOrder.php

  2. <?php
  4. namespace DesignPatterns\Behavioral\State;
  6. abstract class StateOrder
  7. {
  8.     /**
  9.      * @var array
  10.      */
  11.     private $details;
  13.     /**
  14.      * @var StateOrder $state
  15.      */
  16.     protected static $state;
  18.     /**
  19.      * @return mixed
  20.      */
  21.     abstract protected function done();
  23.     protected function setStatus(string $status)
  24.     {
  25.         $this->details['status'] = $status;
  26.         $this->details['updatedTime'] = time();
  27.     }
  29.     protected function getStatus(): string
  30.     {
  31.         return $this->details['status'];
  32.     }
  33. }

ShippingOrder.php

  2. <?php
  4. namespace DesignPatterns\Behavioral\State;
  6. class ShippingOrder extends StateOrder
  7. {
  8.     public function __construct()
  9.     {
  10.         $this->setStatus('shipping');
  11.     }
  13.     protected function done()
  14.     {
  15.         $this->setStatus('completed');
  16.     }
  17. }

CreateOrder.php

  2. <?php
  4. namespace DesignPatterns\Behavioral\State;
  6. class CreateOrder extends StateOrder
  7. {
  8.     public function __construct()
  9.     {
  10.         $this->setStatus('created');
  11.     }
  13.     protected function done()
  14.     {
  15.         static::$state = new ShippingOrder();
  16.     }
  17. }

测试

Tests/StateTest.php

  2. <?php
  4. namespace DesignPatterns\Behavioral\State\Tests;
  6. use DesignPatterns\Behavioral\State\ContextOrder;
  7. use DesignPatterns\Behavioral\State\CreateOrder;
  8. use DesignPatterns\Behavioral\State\ShippingOrder;
  9. use PHPUnit\Framework\TestCase;
  11. class StateTest extends TestCase
  12. {
  13.     public function testCanShipCreatedOrder()
  14.     {
  15.         $order = new CreateOrder();
  16.         $contextOrder = new ContextOrder();
  17.         $contextOrder->setState($order);
  18.         $contextOrder->done();
  20.         $this->assertEquals('shipping', $contextOrder->getStatus());
  21.     }
  23.     public function testCanCompleteShippedOrder()
  24.     {
  25.         $order = new ShippingOrder();
  26.         $contextOrder = new ContextOrder();
  27.         $contextOrder->setState($order);
  28.         $contextOrder->done();
  30.         $this->assertEquals('completed', $contextOrder->getStatus());
  31.     }
  32. }