一、final指定某个类不允许被继承或者是某个方法不允许被修改： 1、类A不允许类B继承： 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{ }//报错： Class B may not inherit from final class (A)*/ 2、类A中的方法show不允许被重写或修改： 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岁','180cm'); echo $a->show(); class B extends A{ function show(){ return $this->name; } } $b = new B('zyy','24','172cm'); $b->show();//报错： Cannot override final method A::show() 二、const指定类常量，仅限这个类进行调用，类的实例对象也不能调用： class A{ private $name; private $sex; const work = 'web前端开发'; function __construct($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前端开发