一、观察者模式
-
当一个对象状态发生改变时,依赖它的对象全部会收到通知,并自动更新
-
场景:一个事件发生后,要执行一连串更新操作。传统的编程方式,就是在事件的代码之后直接加入处理逻辑。当更新的逻辑增多之后,代码会变得难以维护。这种方式是藕合的,侵入式的,增加新的逻辑需要修改事件主体的代码
-
观察者模式实现了低耦合,非侵入式的通知与更新机制
<?php
interface watcher{public function update();
}
abstract class watch{private $watchArr = array();public function addWatchArr(watcher $watcher){$this->watchArr[] = $watcher;}public function notify(){foreach($this->watchArr as $value){$value->update();}}
}
class watcher1 implements watcher{public function update(){echo "update watcher1";}
}
class watcher2 implements watcher{public function update(){echo "update watcher2";}
}
class main extends watch{public function test(){echo "update1";$watcher1 = new watcher1();$watcher2 = new watcher2();$this->addWatchArr($watcher1);$this->addWatchArr($watcher2);$this->notify();
}
}
$main = new main();
$main->test();
上面的interface{} 为每个实例提供了统一的方法,那么抽象方法提供了添加实例以及统一遍历实例的方法。
二、适配器模式
-
适配器模式,可以将截然不同的函数接口封装成统一的API
-
实际应用举例,PHP 的数据库操作有mysql,mysqli 等,可以通过适配器模式统一成一致
interface database{public function connect();public function query();
public function delete();
}
class mysql implements database{public function connect(){
}
public function query(){
}
public function delete(){}
}
三、策略模式
-
策略模式,将一组特定的行为和算法封装成类,以适应某些特定的上下文环境,这种模式就是策略模式
-
使用策略模式可以实现IOC,依赖倒置、控制反转
<?php
interface advertise{public function show();
}
class man implements advertise{ public function show(){echo "显示man";}
}
class woman implements advertise{public function show(){echo "显示woman";}
}
class showindex{private $advertise;public function addObject(advertise $advertise){$this->advertise = $advertise;}public function index(){$this->advertise->show();}
}
$showindex = new showindex();
$women = new woman();
$showindex->addObject($women);
$showindex->index();
四、装饰器模式
-
装饰器模式,可以动态地添加修改类的功能
-
一个类提供了一项功能,如果修改并添加额外的功能,传统的编程模式,需要写一个子类继承它,并重新实现类的方法
-
使用装饰器模式,仅需在运行时添加一个装饰器对象即可实现,可以实现最大的灵活性
interface drawInterface{public function beforeDraw();public function afterDraw();
}
class Draw{
private $addDraw = array();public function addDrwa(drawInterface $draw){$this->addDraw[] = $draw;}private function beforeDraw(){foreach($this->addDraw as $row){$row->beforeDraw();}}
private function afterDraw(){$t = array_reverse($this->addDraw);foreach($t as $row){$row->afterDraw();}}public function show(){$this->beforeDraw();echo "*";$this->afterDraw();}
}
class A implements drawInterface{public function beforeDraw(){echo "<h1>";}public function afterDraw(){echo "</h1>";}
}
class B implements drawInterface{public function beforeDraw(){echo "<h2>";}public function afterDraw(){echo "</h2>";}
}
$draw = new Draw();
$draw->addDrwa(new A());
$draw->addDrwa(new B());
$draw->show();