状态模式
目的
根据对象的状态，对相同例行程序的不同行为进行封装。这是对象在运行时改变其行为的一种更简洁的方式，而不需要借助庞大的条件语句。
UML 类图
代码
OrderContext.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State;
class OrderContext
{
private State $state;
public static function create(): OrderContext
{
$order = new self();
$order->state = new StateCreated();
return $order;
}
public function setState(State $state)
{
$this->state = $state;
}
public function proceedToNext()
{
$this->state->proceedToNext($this);
}
public function toString()
{
return $this->state->toString();
}
}
|
State.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State;
interface State
{
public function proceedToNext(OrderContext $context);
public function toString(): string;
}
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StateCreated.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State;
class StateCreated implements State
{
public function proceedToNext(OrderContext $context)
{
$context->setState(new StateShipped());
}
public function toString(): string
{
return 'created';
}
}
|
StateShipped.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State;
class StateShipped implements State
{
public function proceedToNext(OrderContext $context)
{
$context->setState(new StateDone());
}
public function toString(): string
{
return 'shipped';
}
}
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StateDone.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State;
class StateDone implements State
{
public function proceedToNext(OrderContext $context)
{
}
public function toString(): string
{
return 'done';
}
}
|
测试
Tests/StateTest.php
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| <?php declare(strict_types = 1);
namespace DesignPatterns\Behavioral\State\Tests;
use DesignPatterns\Behavioral\State\OrderContext;
use PHPUnit\Framework\TestCase;
class StateTest extends TestCase
{
public function testIsCreatedWithStateCreated()
{
$orderContext = OrderContext::create();
$this->assertSame('created', $orderContext->toString());
}
public function testCanProceedToStateShipped()
{
$contextOrder = OrderContext::create();
$contextOrder->proceedToNext();
$this->assertSame('shipped', $contextOrder->toString());
}
public function testCanProceedToStateDone()
{
$contextOrder = OrderContext::create();
$contextOrder->proceedToNext();
$contextOrder->proceedToNext();
$this->assertSame('done', $contextOrder->toString());
}
public function testStateDoneIsTheLastPossibleState()
{
$contextOrder = OrderContext::create();
$contextOrder->proceedToNext();
$contextOrder->proceedToNext();
$contextOrder->proceedToNext();
$this->assertSame('done', $contextOrder->toString());
}
}
|
