状态设计模式的关键就是，环境中拥有所需的全部状态对象，每个状态对象又引用了环境对象；环境对象通过维护一个当前状态属性（用于存放状态对象）从而对所需的全部状态对象产生影响。
下面演示了一个简单的状态设计模式，状态设计模式的核心在于47-49行：
?1 <?php ?2 ??3 interface Status ?4 { ?5 ????function getProperty(); ?6 ????function getContext(); ?7 } ?8 ??9 abstract class BaseStatus implements Status 10 { 11 ????public $context; 12 ?13 ????public function __construct(BaseContext $context) 14 ????{ 15 ????????$this->context = $context; 16 ????} 17 ?18 ????public function getContext() 19 ????{ 20 ????????return $this->context; 21 ????} 22 } 23 ?24 abstract class BaseContext 25 { 26 ????public $currentStatus; 27 ?28 ????public function changeStatus(Status $status) 29 ????{ 30 ????????$this->currentStatus = $status; 31 ????} 32 ?33 ????public function statusDetail() 34 ????{ 35 ????????return $this->currentStatus->getProperty(); 36 ????} 37 } 38 ?39 class Context extends BaseContext 40 { 41 ????public $status1; 42 ????public $status2; 43 ????public $status3; 44 ?45 ????public function __construct() 46 ????{ 47 ????????$this->status1 = new Status1($this); 48 ????????$this->status2 = new Status2($this); 49 ????????$this->status3 = new Status3($this); 50 ?51 ????????$this->currentStatus = $this->status1; 52 ????} 53 } 54 ?55 class Status1 extends BaseStatus 56 { 57 ????public function getProperty() 58 ????{ 59 ????????echo ‘I am status1‘.PHP_EOL; 60 ????????if ($this->getContext()->currentStatus instanceof self) { 61 ????????????echo ‘here is status two and status three<br/>‘; 62 ????????????$this->context->status2->getProperty(); 63 ????????????echo ‘<br/>‘; 64 ????????????$this->context->status3->getProperty(); 65 ????????????echo ‘<br/>‘; 66 ????????} 67 ????} 68 } 69 ?70 class Status2 extends BaseStatus 71 { 72 ????public function getProperty() 73 ????{ 74 ????????echo ‘I am status2‘.PHP_EOL; 75 ????????if ($this->getContext()->currentStatus instanceof self) { 76 ????????????echo ‘here is status one and status three<br/>‘; 77 ????????????$this->context->status1->getProperty(); 78 ????????????echo ‘<br/>‘; 79 ????????????$this->context->status3->getProperty(); 80 ????????????echo ‘<br/>‘; 81 ????????} 82 ????} 83 } 84 ?85 class Status3 extends BaseStatus 86 { 87 ????public function getProperty() 88 ????{ 89 ????????echo ‘I am status3‘.PHP_EOL; 90 ????????if ($this->getContext()->currentStatus instanceof self) { 91 ????????????echo ‘here is status one and status two<br/>‘; 92 ????????????$this->context->status1->getProperty(); 93 ????????????echo ‘<br/>‘; 94 ????????????$this->context->status2->getProperty(); 95 ????????????echo ‘<br/>‘; 96 ????????} 97 ????} 98 } 99 100 $context = new Context();101 102 $context->statusDetail();103 104 $context->changeStatus($context->status2);105 106 $context->statusDetail();107 108 $context->changeStatus($context->status3);109 110 $context->statusDetail();运行结果：
I am status1 here is status two and status three
I am status2
I am status3
I am status2 here is status one and status three
I am status1
I am status3
I am status3 here is status one and status two
I am status1
I am status2
可见，每次环境对象切换状态的时候，环境对象内的任何修改对于所有状态对象都是同步可见的（状态对象均引用了环境对象）。
php状态设计模式
原文地址：https://www.cnblogs.com/SHQHDMR/p/9721474.html