一、final指定某個類不允許被繼承或者是某個方法不允許被修改： 1、類A不允許類B繼承： final class A{ private $name; private $age; private $height; function __construct($a,$b,$c){ $this->name = $a; $this->age = $b; $this->height = $c; } final function show(){ return $this->height; } } class B extends A{ }//報錯： Class B may not inherit from final class (A)*/ 2、類A中的方法show不允許被重寫或修改： class A{ private $name; private $age; private $height; function __construct($a,$b,$c){ $this->name = $a; $this->age = $b; $this->height = $c; } final function show(){ return $this->height; } } $a = new A('zym','23歲','180cm'); echo $a->show(); class B extends A{ function show(){ return $this->name; } } $b = new B('zyy','24','172cm'); $b->show();//報錯： Cannot override final method A::show() 二、const指定類常量，僅限這個類進行調用，類的實例對象也不能調用： class A{ private $name; private $sex; const work = 'web前端開發'; function __construct($a,$b){ $this->name = $a; $this->sex = $b; } public function show(){ return $this->name.'的工作是'.self::work; } } $a = new A('fxxy','男'); echo $a->show();//fxxy的工作是web前端開發